Hubbry Logo
Coronal mass ejectionCoronal mass ejectionMain
Open search
Coronal mass ejection
Community hub
Coronal mass ejection
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Contribute something
Coronal mass ejection
Coronal mass ejection
Coronal mass ejection
View on Wikipedia
from Wikipedia

When observed in white-light coronagraph imagery, CMEs sometimes resemble a light bulb, possessing a bright bulb-like outer shell surrounding a dark void and compact inner structure.[1]

A coronal mass ejection (CME) is a significant ejection of plasma mass from the Sun's corona into the heliosphere. CMEs are often associated with solar flares and other forms of solar activity, but a broadly accepted theoretical understanding of these relationships has not been established.

If a CME enters interplanetary space, it is sometimes referred to as an interplanetary coronal mass ejection (ICME). ICMEs are capable of reaching and colliding with Earth's magnetosphere, where they can cause geomagnetic storms, aurorae, and in rare cases damage to electrical power grids. The largest recorded geomagnetic perturbation, resulting presumably from a CME, was the solar storm of 1859. Also known as the Carrington Event, it disabled parts of the newly created United States telegraph network, starting fires and electrically shocking some telegraph operators.

Near solar maxima, the Sun produces about three CMEs every day, whereas near solar minima, there is about one CME every five days.

Physical description

[edit]

CMEs release large quantities of matter from the Sun's atmosphere into the solar wind and interplanetary space. The ejected matter is a plasma consisting primarily of electrons and protons embedded within its magnetic field. This magnetic field is commonly in the form of a flux rope, a helical magnetic field with changing pitch angles.

The average mass ejected is 1.6×1012 kg (3.5×1012 lb). However, the estimated mass values for CMEs are only lower limits, because coronagraph measurements provide only two-dimensional data.

CMEs erupt from strongly twisted or sheared, large-scale magnetic field structures in the corona that are kept in equilibrium by overlying magnetic fields.

Origin

[edit]
Simplified model of magnetic fields emerging from the photosphere

CMEs erupt from the lower corona, where processes associated with the local magnetic field dominate over other processes. As a result, the coronal magnetic field plays an important role in the formation and eruption of CMEs. Pre-eruption structures originate from magnetic fields that are initially generated in the Sun's interior by the solar dynamo. These magnetic fields rise to the Sun's surface—the photosphere—where they may form localized areas of highly concentrated magnetic flux and expand into the lower solar atmosphere forming active regions. At the photosphere, active region magnetic flux is often distributed in a dipole configuration, that is, with two adjacent areas of opposite magnetic polarity across which the magnetic field arches. Over time, the concentrated magnetic flux cancels and disperses across the Sun's surface, merging with the remnants of past active regions to become a part of the quiet Sun. Pre-eruption CME structures can be present at different stages of the growth and decay of these regions, but they always lie above polarity inversion lines (PIL), or boundaries across which the sign of the vertical component of the magnetic field reverses. PILs may exist in, around, and between active regions or form in the quiet Sun between active region remnants. More complex magnetic flux configurations, such as quadrupolar fields, can also host pre-eruption structures.[2][3]

In order for pre-eruption CME structures to develop, large amounts of energy must be stored and be readily available to be released. As a result of the dominance of magnetic field processes in the lower corona, the majority of the energy must be stored as magnetic energy. The magnetic energy that is freely available to be released from a pre-eruption structure, referred to as the magnetic free energy or nonpotential energy of the structure, is the excess magnetic energy stored by the structure's magnetic configuration relative to that stored by the lowest-energy magnetic configuration the underlying photospheric magnetic flux distribution could theoretically take, a potential field state. Emerging magnetic flux and photospheric motions continuously shifting the footpoints of a structure can result in magnetic free energy building up in the coronal magnetic field as twist or shear.[4] Some pre-eruption structures, referred to as sigmoids, take on an S or reverse-S shape as shear accumulates. This has been observed in active region coronal loops and filaments with forward-S sigmoids more common in the southern hemisphere and reverse-S sigmoids more common in the northern hemisphere.[5][6]

Magnetic flux ropes—twisted and sheared magnetic flux tubes that can carry electric current and magnetic free energy—are an integral part of the post-eruption CME structure; however, whether flux ropes are always present in the pre-eruption structure or whether they are created during the eruption from a strongly sheared core field (see § Initiation) is subject to ongoing debate.[4][7]

Some pre-eruption structures have been observed to support prominences, also known as filaments, composed of much cooler material than the surrounding coronal plasma. Prominences are embedded in magnetic field structures referred to as prominence cavities, or filament channels, which may constitute part of a pre-eruption structure (see § Coronal signatures).

Early evolution

[edit]

The early evolution of a CME involves its initiation from a pre-eruption structure in the corona and the acceleration that follows. The processes involved in the early evolution of CMEs are poorly understood due to a lack of observational evidence.

Initiation

[edit]

CME initiation occurs when a pre-eruption structure in an equilibrium state enters a nonequilibrium or metastable state where energy can be released to drive an eruption. The specific processes involved in CME initiation are debated, and various models have been proposed to explain this phenomenon based on physical speculation. Furthermore, different CMEs may be initiated by different processes.[7]: 175 [8]: 303 

It is unknown whether a magnetic flux rope exists prior to initiation, in which case either ideal or non-ideal magnetohydrodynamic (MHD) processes drive the expulsion of this flux rope, or whether a flux rope is created during the eruption by non-ideal process.[9][10]: 555  Under ideal MHD, initiation may involve ideal instabilities or catastrophic loss of equilibrium along an existing flux rope:[4]

  • The kink instability occurs when a magnetic flux rope is twisted to a critical point, whereupon the flux rope is unstable to further twisting.
  • The torus instability occurs when the magnetic field strength of an arcade overlying a flux rope decreases rapidly with height. When this decrease is sufficiently rapid, the flux rope is unstable to further expansion.[11]
  • The catastrophe model involves a catastrophic loss of equilibrium.

Under non-ideal MHD, initiations mechanisms may involve resistive instabilities or magnetic reconnection:

  • Tether-cutting, or flux cancellation, occurs in strongly sheared arcades when nearly antiparallel field lines on opposite sides of the arcade form a current sheet and reconnect with each other. This can form a helical flux rope or cause a flux rope already present to grow and its axis to rise.
  • The magnetic breakout model consists of an initial quadrupolar magnetic topology with a null point above a central flux system. As shearing motions cause this central flux system to rise, the null point forms a current sheet and the core flux system reconnects with the overlying magnetic field.[10]
Video of a solar filament being launched

Initial acceleration

[edit]

Following initiation, CMEs are subject to different forces that either assist or inhibit their rise through the lower corona. Downward magnetic tension force exerted by the strapping magnetic field as it is stretched and, to a lesser extent, the gravitational pull of the Sun oppose movement of the core CME structure. In order for sufficient acceleration to be provided, past models have involved magnetic reconnection below the core field or an ideal MHD process, such as instability or acceleration from the solar wind.

In the majority of CME events, acceleration is provided by magnetic reconnection cutting the strapping field's connections to the photosphere from below the core and outflow from this reconnection pushing the core upward. When the initial rise occurs, the opposite sides of the strapping field below the rising core are oriented nearly antiparallel to one another and are brought together to form a current sheet above the PIL. Fast magnetic reconnection can be excited along the current sheet by microscopic instabilities, resulting in the rapid release of stored magnetic energy as kinetic, thermal, and nonthermal energy. The restructuring of the magnetic field cuts the strapping field's connections to the photosphere thereby decreasing the downward magnetic tension force while the upward reconnection outflow pushes the CME structure upwards. A positive feedback loop results as the core is pushed upwards and the sides of the strapping field are brought in closer and closer contact to produce additional magnetic reconnection and rise. While upward reconnection outflow accelerates the core, simultaneous downward outflow is sometimes responsible for other phenomena associated with CMEs (see § Coronal signatures).

In cases where significant magnetic reconnection does not occur, ideal MHD instabilities or the dragging force from the solar wind can theoretically accelerate a CME. However, if sufficient acceleration is not provided, the CME structure may fall back in what is referred to as a failed or confined eruption.[10][4]

Coronal signatures

[edit]

The early evolution of CMEs is frequently associated with other solar phenomena observed in the low corona, such as eruptive prominences and solar flares. CMEs that have no observed signatures are sometimes referred to as stealth CMEs.[12][13]

Prominences embedded in some CME pre-eruption structures may erupt with the CME as eruptive prominences. Eruptive prominences are associated with at least 70% of all CMEs[14] and are often embedded within the bases of CME flux ropes. When observed in white-light coronagraphs, the eruptive prominence material, if present, corresponds to the observed bright core of dense material.[8]

When magnetic reconnection is excited along a current sheet of a rising CME core structure, the downward reconnection outflows can collide with loops below to form a cusp-shaped, two-ribbon solar flare.

CME eruptions can also produce EUV waves, also known as EIT waves after the Extreme ultraviolet Imaging Telescope or as Moreton waves when observed in the chromosphere, which are fast-mode MHD wave fronts that emanate from the site of the CME.[7][4]

A coronal dimming is a localized decrease in extreme ultraviolet and soft X-ray emissions in the lower corona. When associated with a CME, coronal dimmings are thought to occur predominantly due to a decrease in plasma density caused by mass outflows during the expansion of the associated CME. They often occur either in pairs located within regions of opposite magnetic polarity, a core dimming, or in a more widespread area, a secondary dimming. Core dimmings are interpreted as the footpoint locations of the erupting flux rope; secondary dimmings are interpreted as the result of the expansion of the overall CME structure and are generally more diffuse and shallow.[15] Coronal dimming was first reported in 1974,[16] and, due to their appearance resembling that of coronal holes, they were sometimes referred to as transient coronal holes.[17]

Propagation

[edit]

Observations of CMEs are typically through white-light coronagraphs which measure the Thomson scattering of sunlight off of free electrons within the CME plasma.[18] An observed CME may have any or all of three distinctive features: a bright core, a dark surrounding cavity, and a bright leading edge.[19] The bright core is usually interpreted as a prominence embedded in the CME (see § Origin) with the leading edge as an area of compressed plasma ahead of the CME flux rope. However, some CMEs exhibit more complex geometry.[8]

From white-light coronagraph observations, CMEs have been measured to reach speeds in the plane-of-sky ranging from 20 to 3,200 km/s (12 to 2,000 mi/s) with an average speed of 489 km/s (304 mi/s).[20] Observations of CME speeds indicate that CMEs tend to accelerate or decelerate until they reach the speed of the solar wind (§ Interactions in the heliosphere).

When observed in interplanetary space at distances greater than about 50 solar radii (0.23 AU) away from the Sun, CMEs are sometimes referred to as interplanetary CMEs, or ICMEs.[7]: 4 

Interactions in the heliosphere

[edit]

As CMEs propagate through the heliosphere, they may interact with the surrounding solar wind, the interplanetary magnetic field, and other CMEs and celestial bodies.

CMEs can experience aerodynamic drag forces that act to bring them to kinematic equilibrium with the solar wind. As a consequence, CMEs faster than the solar wind tend to slow down whereas CMEs slower than the solar wind tend to speed up until their speed matches that of the solar wind.[21]

How CMEs evolve as they propagate through the heliosphere is poorly understood. Models of their evolution have been proposed that are accurate to some CMEs but not others. Aerodynamic drag and snowplow models assume that ICME evolution is governed by its interactions with the solar wind. Aerodynamic drag alone may be able to account for the evolution of some ICMEs, but not all of them.[7]: 199 

Follow a CME as it passes Venus then Earth, and explore how the Sun drives Earth's winds and oceans

CMEs typically reach Earth one to five days after leaving the Sun. The strongest deceleration or acceleration occurs close to the Sun, but it can continue even beyond Earth orbit (1 AU), which was observed using measurements at Mars[22] and by the Ulysses spacecraft.[23] ICMEs faster than about 500 km/s (310 mi/s) eventually drive a shock wave.[24] This happens when the speed of the ICME in the frame of reference moving with the solar wind is faster than the local fast magnetosonic speed. Such shocks have been observed directly by coronagraphs[25] in the corona, and are related to type II radio bursts. They are thought to form sometimes as low as 2 R☉ (solar radii). They are also closely linked with the acceleration of solar energetic particles.[26]

As ICMEs propagate through the interplanetary medium, they may collide with other ICMEs in what is referred to as CME–CME interaction or CME cannibalism.[10]: 599 

During such CME-CME interactions, the first CME may clear the way for the second one[27][28][29] and/or when two CMEs collide[30][31] it can lead to more severe impacts on Earth. Historical records show that the most extreme space weather events involved multiple successive CMEs. For example, the famous Carrington event in 1859 had several eruptions and caused auroras to be visible at low latitudes for four nights.[32] Similarly, the solar storm of September 1770 lasted for nearly nine days, and caused repeated low-latitude auroras.[33] The interaction between two moderate CMEs between the Sun and Earth can create extreme conditions on Earth. Recent studies have shown that the magnetic structure in particular its chirality/handedness, of a CME can greatly affect how it interacts with Earth's magnetic field. This interaction can result in the conservation or loss of magnetic flux, particularly its southward magnetic field component, through magnetic reconnection with the interplanetary magnetic field.[34]

Morphology

[edit]

In the solar wind, CMEs manifest as magnetic clouds. They have been defined as regions of enhanced magnetic field strength, smooth rotation of the magnetic field vector, and low proton temperature.[35] The association between CMEs and magnetic clouds was made by Burlaga et al. in 1982 when a magnetic cloud was observed by Helios-1 two days after being observed by the Solar Maximum Mission (SMM).[36] However, because observations near Earth are usually done by a single spacecraft, many CMEs are not seen as being associated with magnetic clouds. The typical structure observed for a fast CME by a satellite such as the Advanced Composition Explorer (ACE) is a fast-mode shock wave followed by a dense (and hot) sheath of plasma (the downstream region of the shock) and a magnetic cloud.

Other signatures of magnetic clouds are now used in addition to the one described above: among other, bidirectional superthermal electrons, unusual charge state or abundance of iron, helium, carbon, and/or oxygen.

The typical time for a magnetic cloud to move past a satellite at the Lagrange Point (L1 point) is 1 day corresponding to a radius of 0.15 AU with a typical speed of 450 km/s (280 mi/s) and magnetic field strength of 20 nT.[37]

Solar cycle

[edit]
Further information: Solar cycle

The frequency of ejections depends on the phase of the solar cycle: from about 0.2 per day near the solar minimum to 3.5 per day near the solar maximum.[38] However, the peak CME occurrence rate is often 6–12 months after sunspot number reaches its maximum.[4]

Impact on Earth

[edit]
Photo from the ISS of aurora australis during a geomagnetic storm on 29 May 2010. The storm was most likely caused by a CME that had erupted from the Sun on 24 May 2010, five days prior to the storm.
This video features two model runs. One looks at a moderate CME from 2006. The second run examines the consequences of a large CME such as the Carrington-class CME of 1859.

Only a very small fraction of CMEs are directed toward, and reach, the Earth. A CME arriving at Earth results in a shock wave causing a geomagnetic storm that may disrupt Earth's magnetosphere, compressing it on the day side and extending the night-side magnetic tail. When the magnetosphere reconnects on the nightside, it releases power on the order of terawatts directed back toward Earth's upper atmosphere.[citation needed] This can result in events such as the March 1989 geomagnetic storm.

CMEs, along with solar flares, can disrupt radio transmissions and cause damage to satellites and electrical transmission line facilities, resulting in potentially massive and long-lasting power outages.[39][40]

Shocks in the upper corona driven by CMEs can also accelerate solar energetic particles toward the Earth resulting in gradual solar particle events. Interactions between these energetic particles and the Earth can cause an increase in the number of free electrons in the ionosphere, especially in the high-latitude polar regions, enhancing radio wave absorption, especially within the D-region of the ionosphere, leading to polar cap absorption events.[41]

The interaction of CMEs with the Earth's magnetosphere leads to dramatic changes in the outer radiation belt, with either a decrease or an increase of relativistic particle fluxes by orders of magnitude.[quantify][42] The changes in radiation belt particle fluxes are caused by acceleration, scattering and radial diffusion of relativistic electrons, due to the interactions with various plasma waves.[43]

Halo coronal mass ejections

[edit]

A halo coronal mass ejection is a CME which appears in white-light coronagraph observations as an expanding ring completely surrounding the occulting disk of the coronagraph. Halo CMEs are interpreted as CMEs directed toward or away from the observing coronagraph. When the expanding ring does not completely surround the occulting disk, but has an angular width of more than 120 degrees around the disk, the CME is referred to as a partial halo coronal mass ejection. Partial and full halo CMEs have been found to make up about 10% of all CMEs with about 4% of all CMEs being full halo CMEs.[1] Frontside, or Earth-direct, halo CMEs are often associated with Earth-impacting CMEs; however, not all frontside halo CMEs impact Earth.[44]

Future risk

[edit]

In 2019, researchers used an alternative method (Weibull distribution) and estimated the chance of Earth being hit by a Carrington-class storm in the next decade to be between 0.46% and 1.88%.[45]

History

[edit]
Further information: Solar observation

First traces

[edit]

CMEs have been observed indirectly for thousands of years via aurora. Other indirect observations that predated the discovery of CMEs were through measurements of geomagnetic perturbations, radioheliograph measurements of solar radio bursts, and in-situ measurements of interplanetary shocks.[7]

The largest recorded geomagnetic perturbation, resulting presumably from a CME, coincided with the first-observed solar flare on 1 September 1859. The resulting solar storm of 1859 is referred to as the Carrington Event. The flare and the associated sunspots were visible to the naked eye, and the flare was independently observed by English astronomers R. C. Carrington and R. Hodgson. At around the same time as the flare, a magnetometer at Kew Gardens recorded what would become known as a magnetic crochet, a magnetic field detected by ground-based magnetometers induced by a perturbation of Earth's ionosphere by ionizing soft X-rays. This could not easily be understood at the time because it predated the discovery of X-rays in 1895 and the recognition of the ionosphere in 1902.

About 18 hours after the flare, further geomagnetic perturbations were recorded by multiple magnetometers as a part of a geomagnetic storm. The storm disabled parts of the recently created US telegraph network, starting fires and shocking some telegraph operators.[40]

First optical observations

[edit]

The first optical observation of a CME was made on 14 December 1971 using the coronagraph of Orbiting Solar Observatory 7 (OSO-7). It was first described by R. Tousey of the Naval Research Laboratory in a research paper published in 1973.[46] The discovery image (256 × 256 pixels) was collected on a Secondary Electron Conduction (SEC) vidicon tube, transferred to the instrument computer after being digitized to 7 bits. Then it was compressed using a simple run-length encoding scheme and sent down to the ground at 200 bit/s. A full, uncompressed image would take 44 minutes to send down to the ground. The telemetry was sent to ground support equipment (GSE) which built up the image onto Polaroid print. David Roberts, an electronics technician working for NRL who had been responsible for the testing of the SEC-vidicon camera, was in charge of day-to-day operations. He thought that his camera had failed because certain areas of the image were much brighter than normal. But on the next image the bright area had moved away from the Sun and he immediately recognized this as being unusual and took it to his supervisor, Dr. Guenter Brueckner,[47] and then to the solar physics branch head, Dr. Tousey. Earlier observations of coronal transients or even phenomena observed visually during solar eclipses are now understood as essentially the same thing.

Instruments

[edit]

On 1 November 1994, NASA launched the Wind spacecraft as a solar wind monitor to orbit Earth's L1 Lagrange point as the interplanetary component of the Global Geospace Science (GGS) Program within the International Solar Terrestrial Physics (ISTP) program. The spacecraft is a spin axis-stabilized satellite that carries eight instruments measuring solar wind particles from thermal to greater than MeV energies, electromagnetic radiation from DC to 13 MHz radio waves, and gamma-rays.[citation needed]

On 25 October 2006, NASA launched STEREO, two near-identical spacecraft which, from widely separated points in their orbits, are able to produce the first stereoscopic images of CMEs and other solar activity measurements. The spacecraft orbit the Sun at distances similar to that of Earth, with one slightly ahead of Earth and the other trailing. Their separation gradually increased so that after four years they were almost diametrically opposite each other in orbit.[48][49]

Notable coronal mass ejections

[edit]
Further information: List of solar storms

On 9 March 1989, a CME occurred, which struck Earth four days later on 13 March. It caused power failures in Quebec, Canada and short-wave radio interference.

On 23 July 2012, a large, and potentially damaging CME occurred but missed Earth,[50][51] an event that many scientists consider to be a Carrington-class event.

On 14 October 2014, an ICME was photographed by the Sun-watching spacecraft PROBA2 (ESA), Solar and Heliospheric Observatory (ESA/NASA), and Solar Dynamics Observatory (NASA) as it left the Sun, and STEREO-A observed its effects directly at 1 astronomical unit (AU). ESA's Venus Express gathered data. The CME reached Mars on 17 October and was observed by the Mars Express, MAVEN, Mars Odyssey, and Mars Science Laboratory missions. On 22 October, at 3.1 AU, it reached comet 67P/Churyumov–Gerasimenko, perfectly aligned with the Sun and Mars, and was observed by Rosetta. On 12 November, at 9.9 AU, it was observed by Cassini at Saturn. The New Horizons spacecraft was at 31.6 AU approaching Pluto when the CME passed three months after the initial eruption, and it may be detectable in the data. Voyager 2 has data that can be interpreted as the passing of the CME, 17 months after. The Curiosity rover's RAD instrument, Mars Odyssey, Rosetta and Cassini showed a sudden decrease in galactic cosmic rays (Forbush decrease) as the CME's protective bubble passed by.[52][53]

Stellar coronal mass ejections

[edit]

There have been a small number of CMEs observed on other stars, all of which as of 2016 have been found on red dwarfs.[54] These have been detected mainly by spectroscopy, most often by studying Balmer lines: the material ejected toward the observer causes asymmetry in the blue wing of the line profiles due to Doppler shift.[55] This enhancement can be seen in absorption when it occurs on the stellar disc (the material is cooler than its surroundings), and in emission when it is outside the disc. The observed projected velocities of CMEs range from ≈84 to 5,800 km/s (52 to 3,600 mi/s).[56][57] There are few stellar CME candidates in shorter wavelengths in UV or X-ray data.[58][59][60][61] Compared to activity on the Sun, CME activity on other stars seems to be far less common.[55][62] The low number of stellar CME detections can be caused by lower intrinsic CME rates compared to the models (e.g. due to magnetic suppression), projection effects, or overestimated Balmer signatures because of the unknown plasma parameters of the stellar CMEs.[63]

See also

[edit]

References

[edit]

Further reading

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Coronal mass ejection

View on Grokipedia
from Grokipedia
A coronal mass ejection (CME) is a large expulsion of plasma and from the Sun's corona, forming a massive bubble of magnetized plasma that propagates through the at high speeds. These events release up to a billion tons of coronal material, accelerated to velocities ranging from 200 to 3,000 kilometers per second, far exceeding the typical speed of about 400 km/s. First observed in 1971 using space-based coronagraphs, CMEs are a key driver of solar activity and . The frequency of CMEs follows the Sun's 11-year , occurring roughly once per week at and increasing to two or three per day near . When directed toward , a CME can take 3 to 5 days to arrive, interacting with 's to trigger geomagnetic storms that disrupt power grids, operations, and communications systems. These storms arise from the merging of the CME's magnetic fields with 's, inducing strong electrical currents that can corrode pipelines and overload transformers. In extreme cases, such as the February 2022 event, CMEs have led to the loss of dozens of s due to atmospheric drag from heated upper layers. Monitoring CMEs is crucial for space weather forecasting, with missions like NASA's and providing detailed observations of their initiation, propagation, and impacts. While most CMEs disperse harmlessly in interplanetary space, Earth-directed ones pose risks to technology-dependent , underscoring the need for predictive models to mitigate potential disruptions.

Fundamentals

Definition and Overview

A coronal mass ejection (CME) is defined as a large-scale expulsion of plasma and magnetic fields from the Sun's corona into the . These events involve the ejection of magnetized plasma structures, often appearing as expanding bubbles or loops in coronagraph observations. Typical CMEs eject approximately 101510^{15} to 101610^{16} grams of coronal material at speeds ranging from 250 km/s to 3000 km/s. In terms of scale, CMEs can expand to angular widths exceeding 120 degrees as viewed from the Sun, corresponding to physical sizes up to about 0.5 by the time they reach , and they carry embedded on the order of 102110^{21} to 102210^{22} Mx. The total energy released in a CME, primarily stored in the , ranges from 102510^{25} to 103210^{32} ergs, with contributing significantly to the overall budget. This magnetic origin underscores the role of solar magnetic reconfiguration in driving these ejections. CMEs are distinct from other solar phenomena, such as solar flares, which involve intense bursts of and accelerated particles from but do not entail substantial mass ejection. Unlike prominences—dense, relatively stationary clouds of cool plasma suspended in the corona by magnetic loops—CMEs represent dynamic, propagating eruptions that can incorporate prominence material but are characterized by their outward propagation and heliospheric impact.

Physical Properties

Coronal mass ejections (CMEs) consist primarily of coronal plasma, comprising protons, electrons, and alpha particles ( nuclei), along with trace heavy ions such as carbon, nitrogen, oxygen, neon, magnesium, silicon, sulfur, and iron. Near the Sun, the plasma density in these ejections typically ranges from 10−1710^{-17} to 10−1510^{-15} g/cm³, reflecting variations in the low-coronal environment from which the is expelled. The magnetic structure of CMEs is characterized by flux ropes, in which helical twist around a central axial field, forming a coherent bundle of field lines. The polarity of this helical component often opposes that of the , contributing to the overall twisted configuration observed in eruptions. densities within these structures can reach up to 10410^4 J/m³, representing a significant portion of the stored energy available for release during the ejection. CMEs feature multi-temperature plasma profiles, with the core maintaining temperatures around 10610^6 while the surrounding sheath is cooler, influenced by the ambient coronal conditions. Their average propagation speeds range from 400 to 800 km/s, though faster events can drive fast-mode shocks ahead of the ejecta, compressing and heating the . The kinetic energy of a CME, which quantifies its dynamic impact, is expressed by the equation Ek=12Mv2E_k = \frac{1}{2} M v^2 where MM is the total mass of the ejected plasma and vv is its speed; this form illustrates the quadratic scaling of energy with velocity, emphasizing the role of faster ejections in delivering greater heliospheric influence.

Formation and Dynamics

Origins in the Solar Corona

The solar corona, the Sun's outermost atmospheric layer, features an extremely low plasma density of approximately 10810^8 to 10910^9 particles per cubic centimeter and temperatures ranging from 1 to 2 million Kelvin, creating a tenuous, hot environment where thermal pressure is minimal compared to magnetic forces. These conditions allow magnetic fields to dominate the plasma dynamics, structuring the corona into filamentary features such as loops and open field regions that guide solar wind outflow. The corona's magnetic complexity arises primarily in active regions, localized areas of intense magnetic activity often associated with sunspots—dark, cooler photospheric patches where concentrated magnetic flux emerges from the solar interior. Within these active regions, prominences—dense, cool plasma threads suspended against gravity in dips—and arcade-like structures of overlying loops form potential source regions for coronal mass ejections (CMEs), where magnetic shear from photospheric motions builds up free energy. Sheared fields, twisted by and , introduce instabilities that can lead to eruptive events when the stored magnetic energy exceeds equilibrium thresholds. In the coronal plasma, behavior is largely governed by ideal magnetohydrodynamics (MHD), enforcing the frozen-in condition where field lines move with the plasma; however, non-ideal effects enable , a diffusive process that breaks and rejoins field lines, releasing energy rapidly. Observational and simulation evidence indicates that reconnection in the solar corona proceeds at a fast rate, with the normalized inflow speed vin/vA≈0.1v_{\rm in} / v_A \approx 0.1, where vinv_{\rm in} is the reconnection inflow velocity and vAv_A the Alfvén speed, facilitating the onset of CMEs. Helmet streamers represent quasi-steady coronal structures, comprising closed bipolar magnetic arcades capped by oppositely directed open fields that form a sheet, often overlying active regions or prominences. These streamers delineate the boundary between opposite-polarity and are frequent sites of CME eruptions, particularly from their cusp regions at the apex, where reconnection can open closed fields and eject plasma. The stability of these cusps relies on the balance of magnetic tension and , but accumulated shear or external perturbations can trigger breakout reconnection, initiating the expulsion process.

Initiation and Acceleration

Coronal mass ejections (CMEs) initiate through several proposed mechanisms involving the destabilization of magnetic structures in the solar corona. One prominent model is the catastrophic loss of equilibrium in pre-existing ropes, where gradual photospheric motions build up magnetic shear until the system reaches a critical point, leading to a sudden reconfiguration and eruption. In this scenario, the flux rope, suspended above the by overlying , undergoes a rapid upward once equilibrium is lost, releasing stored . This model, developed by Lin and Forbes, emphasizes the role of global changes without requiring external reconnection triggers. Another key initiation mechanism is tether-cutting reconnection, in which occurs at the base of a sheared arcade, severing restraining "tethers" that hold the flux rope in place and allowing it to erupt. Proposed by Antiochos et al., this process begins with reconnection between oppositely directed fields near the polarity inversion line, forming a flux rope that expands outward as further reconnection ejects the structure. The model explains the frequent association between CMEs and flares, as the reconnection also drives plasma heating. Additionally, the kink instability can trigger eruptions in highly twisted flux ropes, where the helical deformation of the exceeds a critical twist threshold of approximately 2.5π to 3.5π (about 1.25 to 1.75 turns), leading to non-axisymmetric perturbations that destabilize the structure. Simulations by Török and Kliem demonstrate that this ideal magnetohydrodynamic instability initiates a helical motion, often transitioning to full ejection if the overlying field is sufficiently weak. Following initiation, CMEs undergo an impulsive acceleration phase primarily driven by the , J×B\mathbf{J} \times \mathbf{B}, where the J\mathbf{J} interacts with the B\mathbf{B} to propel the plasma outward. This phase propels the ejecta to initial speeds of 100–500 km/s within the inner corona, with rates typically ranging from 100–500 m/s². A simplified expression for the aa in this magnetically dominated regime is a≈(B2/4πρ)1/2ra \approx \frac{(B^2 / 4\pi \rho)^{1/2}}{r}, where ρ\rho is the plasma and rr is the heliocentric , highlighting the inverse dependence on as magnetic tension diminishes. The eruption onset occurs over timescales of minutes to hours, often preceded by a pre-eruptive slow rise phase lasting tens of minutes to hours at velocities of 10–50 km/s, during which the flux rope ascends quasi-statically before rapid . Observational indicators of initiation and early acceleration include coronal dimming regions and extreme ultraviolet (EUV) waves. Dimming regions manifest as localized decreases in EUV and soft X-ray intensity, reflecting the evacuation of plasma as the CME lifts off, with mass losses estimated at 10^{15}–10^{16} g. These dimmings often appear transiently near the eruption site and serve as footprints of the departing flux rope. Concurrently, EUV waves—large-scale propagating disturbances at speeds of 200–1000 km/s—radiate from the eruption site, interpreted as fast-mode magnetosonic waves or plasma compressions excited by the expanding CME. These signatures, detectable via instruments like SDO/AIA, provide early warnings of the event's onset.

Propagation and Interactions

As coronal mass ejections (CMEs) propagate through interplanetary space, they expand radially due to the lower density of the ambient solar wind compared to the corona, increasing their angular width and overall size as they move outward. This expansion is accompanied by deceleration primarily from aerodynamic drag forces exerted by the solar wind, which slows faster-moving CMEs while accelerating slower ones toward the solar wind speed. The speed evolution can be approximated in drag-based models as v(t)≈v0+∫−CdρswAM(v−vsw)2 dtv(t) \approx v_0 + \int -\frac{C_d \rho_{sw} A}{M} (v - v_{sw})^2 \, dt, where v0v_0 is the initial speed, CdC_d is the drag coefficient (typically ≈1 for empirical fits), ρsw\rho_{sw} is the solar wind density, AA is the cross-sectional area, MM is the CME mass, and vswv_{sw} is the solar wind speed; this results in a nonlinear decrease in speed for fast CMEs. Interactions between CMEs and the further modify their propagation. When multiple CMEs are ejected in close succession, they can collide, leading to inelastic mergers where the trailing faster CME catches up to the leading slower one, compressing structures and potentially enhancing shock strengths or altering magnetic properties. Additionally, CMEs may experience deflection from their radial path due to gradients in ambient streams, such as corotating interaction regions, which can steer non-central CMEs eastward or westward depending on the configuration. In the , fast CMEs with speeds exceeding approximately 400–500 km/s relative to the drive forward shocks that accelerate particles and compress the preceding . As CMEs evolve into interplanetary CMEs (ICMEs) farther from the Sun, they exhibit characteristic signatures such as bidirectional flows of suprathermal electrons, indicating trapped plasma along open lines connected to the Sun. Travel times to vary significantly with initial speed, ranging from as little as 15–18 hours for the fastest events (up to ~3000 km/s) to several days for slower ones (~250 km/s).

Morphology and Classification

Structural Features

Coronal mass ejections (CMEs) typically exhibit a characteristic three-part structure when observed in white-light images, consisting of a bright , a low-density cavity, and a dense core embedded within the cavity. The represents compressed plasma piled up ahead of the erupting material, often forming a shock front that enhances and . The cavity is a region of relatively low , interpreted as the volume occupied by a twisted magnetic flux rope, while the core comprises denser prominence or filament material that trails within this cavity. This model, first widely recognized through observations from the (SOHO), provides a framework for understanding the internal organization of CMEs near the Sun. In terms of and , CMEs display angular widths ranging from approximately ° to 120° as measured from the Sun-Earth line in coronagraph observations, with many events showing an average width around 45°. These structures are inherently three-dimensional and often due to radial expansion and interactions with the ambient , leading to broader lateral extents compared to their initial coronal footprints. The arises from non-uniform expansion, where the flanks of the CME spread more rapidly than the apex, resulting in a fan-like or loop-like morphology in stereoscopic views. Internally, the flux rope within the cavity features helical windings, with the degree of twist varying based on the pre-eruptive coronal configuration, as evidenced by signatures in both remote and in-situ measurements. At the , material pile-up creates a high- sheath that contrasts sharply with the cavity's lower , observable through variations in white-light images where the front appears brighter due to enhanced . These contrasts highlight the layered nature of CMEs, with the core's prominence plasma often showing filamentary substructures trailing the rope. As CMEs propagate, their structure evolves into a widening , where the angular width increases with heliocentric distance due to self-similar expansion, facilitating simplified for forecasting arrival times at . This conical evolution captures the overall radial and lateral growth, though real asymmetries persist from the low corona.

Types and Observational Signatures

Coronal mass ejections (CMEs) are classified primarily by their morphology and apparent angular width as observed in white-light coronagraph imagery. Loop-like CMEs, the most common type, display a characteristic three-part structure: a bright leading edge formed by piled-up coronal plasma, a lower-density cavity often enclosing a filament or prominence, and a brighter core representing the erupting magnetic flux rope. These structures typically appear as expanding arcade-like loops with angular widths less than 120 degrees, propagating radially from their solar source regions. Partial-halo CMEs exhibit angular widths between 120 and 360 degrees, encircling only a portion of the coronagraph's occulting disk and often indicating limbward or partially -directed eruptions. In contrast, full-halo CMEs appear to surround the entire occulting disk with a 360-degree apparent width, resulting from projection effects when the CME propagates nearly toward the observer, such as events aimed at . Stealth CMEs represent a distinct category, lacking prominent low-coronal signatures in (EUV) or observations; they emerge without associated flares, dimmings, or post-eruption arcades, yet are detectable in coronagraphs as broad, diffuse ejections originating from quiet-Sun regions or active-region peripheries. Key observational signatures of CMEs span multiple wavelengths and detection methods. In white-light coronagraphs, such as those aboard the (), CMEs are imaged via of photospheric light by free electrons in the ejected plasma, revealing their density enhancements and overall envelope up to several solar radii. Radio signatures include type II bursts, generated by magnetohydrodynamic shocks ahead of the CME propagating through the corona and , manifesting as slowly drifting frequency emissions from metric to decametric wavelengths. In-situ measurements by like or at 1 AU identify CME passages through bidirectional suprathermal electron flows, prolonged southward interplanetary magnetic fields, and low plasma beta conditions within magnetic clouds—coherent, force-free structures comprising about one-third of CMEs. Multi-wavelength observations complement coronagraph data by tracing CME evolution across the solar atmosphere. Soft X-ray emissions from instruments like the Atmospheric Imaging Assembly (AIA) on the highlight reconnection sites and hot plasma associated with CME drivers, often preceding the white-light ejection by minutes. EUV imaging reveals coronal dimmings—regions of depleted density due to mass loss—and expanding loops or supra-arcade downflows linked to the eruption. Recent missions such as NASA's and ESA's have provided close-range and multi-viewpoint observations, revealing finer details of flux rope morphology and early structural evolution near the Sun as of 2023–2025. observations, particularly in the near- to mid-IR range, can detect CME interactions with zodiacal dust or provide spectral diagnostics of cooler ejecta components through lines like those from Fe IX or Si X, aiding in multi-thermal modeling of the plasma. Observing CMEs presents challenges due to inherent limitations in remote-sensing techniques. Projection effects in two-dimensional coronagraph images distort the true three-dimensional geometry, leading to overestimation of speeds for limb events or underestimation of widths for near-disk-center eruptions, which complicates kinematic reconstructions. Non-radial propagation further complicates detection, as CMEs may deflect from their initial radial paths due to interactions with the ambient or large-scale magnetic fields, resulting in asymmetric expansion or unexpected arrival times at 1 AU. These issues underscore the value of stereoscopic viewpoints from missions like , enhanced by recent data from and , for mitigating biases in single-observer data.

Relation to Solar Activity

Solar Cycle Variation

Coronal mass ejections (CMEs) display a pronounced variation in occurrence rate tied to the 11-year , with the frequency increasing dramatically from to maximum. During , the rate averages approximately 0.2 CMEs per day, while at solar maximum, it rises to about 3–5 CMEs per day, reflecting heightened solar magnetic activity. Over the course of a full , observations indicate a total of roughly 10410^4 CMEs, underscoring the cycle's role in driving eruptive events from the Sun's corona. The properties of CMEs also evolve systematically with the phase. At , CMEs are typically faster, with speeds exceeding those at minimum by factors of 1.5–2, and wider in angular extent, often spanning greater heliographic widths due to more complex coronal structures. Latitude distributions shift notably: during minimum, CMEs predominantly originate at high latitudes near the solar poles, forming polar crown filaments, but migrate equatorward during the rising and maximum phases, aligning with the equatorward drift of sunspot activity known as Spörer's law. Statistical analyses from the /LASCO provide key benchmarks for these variations, reporting an overall average CME speed of 470 km/s and a typical ejected of 101510^{15} g across observed events. The CME occurrence rate correlates moderately with the sunspot number, yielding a of approximately r≈0.7r \approx 0.7, indicating that solar surface magnetism is a primary driver of ejection . Longer-term patterns suggest additional modulation by the 22-year Hale cycle, where reversals in the Sun's global magnetic polarity influence CME production rates between consecutive 11-year cycles, potentially leading to asymmetries in activity levels during odd- versus even-numbered cycles.

Associations with Flares and Eruptions

Coronal mass ejections (CMEs) are frequently associated with solar flares, particularly those classified as M- or X-class based on GOES soft X-ray measurements, where approximately 50-60% of such flares are accompanied by a CME. This association is understood through the standard magnetic reconnection model, in which both phenomena originate from the same reconnection site in the solar corona, where twisted magnetic fields release stored energy, accelerating plasma and producing the observed emissions and ejections. In this framework, the reconnection process drives the impulsive energy release seen in flares while simultaneously destabilizing overlying magnetic structures, leading to the expulsion of coronal material as a CME. CMEs are also commonly linked to filament eruptions, where cool, dense plasma threads suspended in the corona—known as prominences or filaments—disappear and contribute material to the . Observations indicate that more than 80% of filament eruptions result in a CME, with the filament often serving as the bright core of the three-part structure observed in white-light coronagraphs. In the symbiotic eruption model, the filament's destabilization through triggers both the flare's radiative output and the CME's propagation, as the erupting filament material interacts with the surrounding hot coronal plasma to form the overall . Temporally, the soft signature of a typically precedes the visible onset of the associated CME by several minutes, reflecting the rapid energy release that initiates the ejection process. The peak soft flux during these events serves as a reliable proxy for the CME's ejection rate, with stronger fluxes correlating to faster and more ive ejections due to reconnection-driven . Not all flares produce CMEs; confined flares, which lack an associated ejection, often occur in regions with strong overlying that constrain the plasma and prevent breakout. These events are characterized by localized energy release without large-scale field reconfiguration, resulting in no observable CME in coronagraph imagery. Such confinement is more prevalent in smaller active regions where the magnetic arcade is robust enough to resist eruption.

Space Weather Impacts

Effects on Earth's Environment

When a coronal mass ejection (CME) reaches , its interaction with the begins with compression of the , the boundary between the and . The southward component of the interplanetary magnetic field (B_z) embedded in the CME facilitates at the dayside , allowing plasma and energy to enter the . This process injects approximately 10^{12} W of power into the during geomagnetic storms, enhancing magnetospheric convection and overall energy loading. The influx of energy and particles from reconnection drives enhanced particle into the auroral zones, significantly amplifying auroral activity. During intense CME-driven storms, charged particles, primarily electrons, precipitate into the upper atmosphere, increasing the global auroral power to levels around 10^{11} to 10^{12} , which can expand auroral displays to lower latitudes. This is modulated by the strength and duration of the southward B_z, leading to substorms and heightened electrodynamic between the and . CMEs also profoundly affect the dynamics of Earth's belts by accelerating electrons to relativistic energies exceeding 1 MeV through wave-particle interactions, such as those involving chorus waves energized by the injected plasma. This acceleration fills the slot region between the inner and outer belts (typically L-shells 2–3), which is normally depleted due to losses, resulting in enhanced fluxes that persist for days to weeks post-storm. Such changes alter the overall structure and intensity of the Van Allen belts, with peak electron energies reaching up to several tens of MeV in extreme events. In the , CME-induced disturbances manifest as enhancements in (TEC) and scintillation, driven by prompt penetration and thermospheric neutral forcing from magnetospheric deposition. These irregularities, often occurring in the equatorial and high-latitude regions, cause rapid fluctuations in ionospheric plasma density, leading to signal scintillation that impacts GPS accuracy by inducing phase delays and variations up to several TEC units. The disturbances peak within hours of CME arrival, correlating with the storm's intensity as measured by southward B_z duration.

Geomagnetic Storms and Technological Risks

Coronal mass ejections (CMEs) can trigger geomagnetic storms when their embedded magnetic fields interact with Earth's , leading to disturbances measured by indices such as the disturbance-storm time (Dst) index, which quantifies the strength of the equatorial ring current. Intense geomagnetic storms are typically defined by a Dst index below -100 nT, reflecting significant enhancement of the ring current due to injected plasma from the . These storms pose substantial risks to technological infrastructure through (GICs), which arise from rapid changes in and flow through long conductive paths like lines. In power grids, GICs up to 100 A can saturate cores, causing overheating, generation, and potential blackouts, as observed in events where grid operators had to disconnect lines to prevent cascading failures. Satellites face damage from high-energy particles associated with CMEs, which can penetrate shielding and degrade or solar panels, leading to operational anomalies or total mission loss in vulnerable low-Earth orbit assets. Aviation encounters elevated during such storms, with crew and passengers at high altitudes receiving doses equivalent to multiple chest X-rays from secondary particles produced in the atmosphere, prompting route adjustments or flight delays to limit health risks. Mitigation strategies rely on forecasting to provide advance warnings, with lead times for Earth-directed CMEs ranging from 15-18 hours for the fastest events to 2-4 days for typical ones, enabling protective actions like grid reconfiguration or satellite safing. The May 2024 , reaching G5 (extreme) levels with Dst minima around -412 nT, exemplified these risks by disrupting high-frequency radio communications, causing GPS signal scintillation affecting , and increasing doses on polar flights, though no major blackouts occurred due to timely alerts and monitoring. Similarly, the November 2025 , reaching G4 (severe) levels from multiple CMEs arriving around November 12, disrupted high-frequency radio communications and enhanced auroral displays to mid-latitudes, with no major infrastructure failures reported due to advance forecasting. A Carrington-level event, like the 1859 with an estimated Dst of around -850 nT (some estimates up to -1760 nT or as low as -900 nT), has a recurrence probability of approximately 1% per decade for Dst < -850 nT based on statistical analyses of historical and paleomagnetic records, potentially resulting in global economic losses exceeding $2 trillion from widespread power outages, satellite failures, and disruptions lasting months.

Halo CMEs and Detection Challenges

Halo (CMEs) are a subset of CMEs directed toward , appearing in observations as bright enhancements that encircle the entire occulting disk of the Sun, creating an illusion of a full solar disk halo. This visual effect occurs because the eruption is oriented limb-on relative to the observer, with the expanding plasma expanding symmetrically around the . Due to projection effects in two-dimensional , the apparent speed of halo CMEs is systematically underestimated compared to their true three-dimensional propagation velocity, often by approximately 20% for events observed near the solar disk center. Detecting and characterizing halo CMEs presents significant challenges due to their ambiguous three-dimensional structure when viewed from a single vantage point, such as . In coronagraph images, the superposition of foreground and background material obscures the true geometry, making it difficult to distinguish the eruption's actual width, orientation, and propagation direction, which can lead to misinterpretations of non-halo events as potential Earth-impacting halos and resultant false alarms in space weather alerts. To mitigate these issues, stereoscopic observations from missions like the Solar Terrestrial Relations Observatory () enable three-dimensional reconstructions by providing simultaneous views from offset angles, allowing for more accurate de-projection and identification of the CME's core structure. Halo CMEs are particularly geoeffective, with approximately 71% of frontside halo events producing geomagnetic storms, largely attributable to their likelihood of carrying southward interplanetary magnetic fields (Bz) that facilitate efficient with 's . This high hit rate underscores their importance in space weather forecasting, though predictions of their arrival at remain uncertain, with typical errors in transit time estimates ranging from 10 to 20 hours due to variability in interactions and initial velocity measurements. A notable recent example is the series of halo CMEs observed in May 2024 from AR 3664, which included multiple fast, Earth-directed eruptions following X-class flares, culminating in a G5-level from May 10 to 12—the strongest since —and widespread auroral displays at low latitudes.

Observation and History

Early Discoveries and Traces

The earliest indications of coronal mass ejections (CMEs) emerged from 19th-century observations of s, which hinted at solar material influencing 's . The most prominent example is the of September 1–2, 1859, during , when astronomer Richard Carrington witnessed an intense white-light in a large group. Concurrently, physicist Balfour Stewart, director of the Kew Observatory, recorded a severe geomagnetic disturbance that disrupted telegraph systems worldwide, establishing a causal link between solar eruptions and terrestrial magnetic perturbations suggestive of ejected plasma streams. This event, the strongest geomagnetic storm in recorded history, underscored the potential for solar ejections to propagate through interplanetary space and impact . In the pre-spacecraft era, additional indirect evidence accumulated from anomalous behaviors in comet tails and geomagnetic records. Discontinuities and sudden kinks in comet tails, observed as early as the mid-20th century, were attributed to transient bursts of high-speed solar corpuscular radiation interacting with the cometary plasma, distinct from the steady inferred by Ludwig Biermann in 1951. For instance, tail disruptions in comets like Morehouse (1908) and others were later reinterpreted as encounters with interplanetary shocks from solar ejections. Complementing this, data revealed sudden commencements—abrupt positive deflections in Earth's horizontal component—correlating with solar activity and interpreted as pressure pulses from arriving solar plasma clouds. These signatures provided conceptual groundwork for discrete mass ejections without direct solar imaging. Conceptual advancements in the mid-20th century further traced CME origins through radio emissions and chromospheric disturbances. In the 1940s, observations of solar bursts, pioneered by figures like at Jodrell Bank, indicated that intense metric-wavelength emissions arose from streams of ionized particles ejected from active regions, implying explosive mass loss from the corona. Building on this, the brought the discovery of Moreton waves by Robert Moreton, who documented large-scale, arc-like propagations in Hα emission across the solar disk at velocities exceeding 1000 km/s during major flares. These waves, spanning hundreds of thousands of kilometers, were recognized as chromospheric projections of fast-mode magnetohydrodynamic shocks in the corona, driven by eruptive events later identified as CMEs. A pivotal synthesis occurred in the 1970s with the first in-situ detections of interplanetary CMEs (ICMEs), confirming the ejection of coronal material into the . Data from Pioneer spacecraft, such as launched in 1972, revealed plasma enhancements and bidirectional flows indicative of expanding magnetic structures. Similarly, and 2, launched in 1977, observed ICMEs between 1 and 10 AU from 1977 to 1980, characterized by low plasma beta, enhanced magnetic fields, and compositional anomalies matching coronal signatures. These findings, including events like the August 1978 ICME studied across multiple probes, solidified the understanding that CMEs were massive, billion-tonne expulsions propagating at hundreds of km/s, reconciling earlier indirect traces with heliospheric dynamics.

Key Instruments and Missions

Ground-based instruments laid the foundation for CME observations by enabling indirect and direct views of solar eruptive phenomena. Bernard Lyot's , invented in the early , created artificial solar eclipses to allow routine visible-light imaging of the corona from Earth's surface, marking a pivotal advance over eclipse-dependent sightings. Complementing optical methods, radio telescopes have detected type II and type IV bursts since the mid-20th century, which are signatures of shock waves and plasma emissions driven by CMEs propagating through the corona and . Space-based missions revolutionized CME studies by providing uninterrupted, high-resolution observations free from atmospheric interference. The Orbiting Solar Observatory 7 (OSO-7), operational from 1971 to 1973, featured the first spaceborne , which captured white-light images revealing 23 CME events and confirming their existence as dynamic solar phenomena. Building on this, the Skylab mission's in 1973–1974 delivered the initial detailed optical imagery of over 110 CMEs, highlighting their morphologies, speeds, and associations with solar surface activity during a period of rising solar activity. The (), launched in 1995, has been instrumental in long-term monitoring through its Large Angle and Spectrometric (LASCO), which has cataloged more than 30,000 CMEs over nearly three decades. LASCO's C2 and C3 coronagraphs offer complementary fields of view spanning approximately 2 to 30 solar radii (R⊙), allowing comprehensive tracking of CME evolution from near-Sun launch to heliospheric propagation and enabling detailed analyses of their three-dimensional structures and kinematics. Subsequent missions enhanced stereoscopic and in-situ capabilities. The twin Solar Terrestrial Relations Observatory (STEREO) spacecraft, STEREO-A and STEREO-B, launched in 2006, provided the first three-dimensional views of CMEs by imaging events from opposing vantage points, revealing their true propagation geometries and internal complexities for over 4,500 eruptive events. Meanwhile, the Wind and (ACE) spacecraft, positioned at the since the mid-1990s, have delivered critical in-situ measurements of interplanetary CMEs (ICMEs), recording plasma, , and compositional signatures to study their heliospheric impacts and geoeffectiveness.

Recent Advances and Simulations

The has provided unprecedented in situ measurements of coronal mass ejections (CMEs) through its close approaches to the Sun, reaching distances as low as approximately 9.9 solar radii during its December 2024 perihelion. These encounters have enabled direct sampling of CME-driven shocks and associated phenomena, including sub-Alfvénic regions induced by CMEs, where plasma flows slower than the local Alfvén speed. For instance, data from the probe's eighth encounter in April 2021 onward revealed consistent sub-Alfvénic conditions linked to CME propagation, offering insights into the early evolution of these structures near the Sun. Additionally, 2024 observations captured nascent CMEs, including bursts of plasma release and Kelvin-Helmholtz instabilities within ejecta, highlighting turbulent mixing at shock interfaces. Complementing these findings, the mission, operational since 2021, has advanced multi-viewpoint imaging of CMEs using its suite of remote-sensing and instruments, such as the Extreme Ultraviolet Imager (EUI) and the Solar Orbiter/HIS (SoloHI) . High-resolution EUV and coronagraphic data from 2023 to 2025 have revealed asymmetric ejections, with east-west detection asymmetries in exceeding 10 MeV, attributed to varying magnetic connectivity and CME geometries. For example, observations of the April 2023 CME that triggered Solar Cycle 25's first severe demonstrated non-uniform expansion and particle acceleration, informed by SoloHI's wide-field views from off-ecliptic vantage points. Joint analyses with data, such as for the September 2022 CME, have modeled global structures, confirming flux rope configurations and radial evolution of interplanetary shocks at distances below 0.8 AU. Magnetohydrodynamic (MHD) simulations have seen significant improvements in CME propagation and interactions, with models like WSA-ENLIL integrating real-time data for 1-4 day predictions of arrival times at . These simulations assimilate observations to refine ambient backgrounds, achieving accurate estimates for events like the January 2025 CMEs. Recent 2025 studies focused on the May 2024 superstorm, driven by multiple interacting CMEs, used MHD frameworks to simulate their evolution, revealing how successive mergers amplified geomagnetic impacts through enhanced shock strengths and prolonged disturbances. Such models, including those in the Space Weather Modeling Framework, have demonstrated that three CMEs arrived nearly simultaneously at , contributing to the event's extremity. Advances in understanding young Sun analogs include spectroscopic detections of multi-temperature CME signatures in pre-main-sequence stars. A 2025 study identified the first evidence of such ejections from the young G dwarf EK Draconis, a approximately 100 million years old, using and ground-based observations to trace hot plasma components across temperatures exceeding 10 million . These findings, revealing filamentary eruptions akin to solar CMEs, suggest frequent mass loss in T Tauri-like phases, informing models of early solar activity and its effects on proto-planetary environments.

Notable Events

Historical Significant CMEs

The of September 1–2, 1859, stands as the most intense in recorded history, inferred to have been triggered by a massive coronal mass ejection (CME) following a powerful observed by Richard Carrington. This event produced widespread auroral displays visible as far south as the and caused global disruptions to telegraph systems, including fires at operators' stations and induced currents that operated lines without batteries. Modern reconstructions estimate the storm's intensity at a disturbance-storm time (Dst) index of approximately −900 nT, with estimates ranging from −800 nT to −1,100 nT, far exceeding typical severe storms. On August 4, 1972, a Carrington-class solar event unleashed an ultra-fast CME associated with a nearly white-light , marking one of the earliest instances of such phenomena captured by space-based observations from the Orbiting Solar Observatory-7 (OSO-7) mission. The CME propagated at an average shock speed of around 2900 km/s, leading to a severe that intensified solar radiation and caused operational failures in at least seven satellites, including disruptions to and power systems. This event highlighted the vulnerability of early space assets, with proton fluxes reaching levels that would have endangered Apollo astronauts if a mission had been underway. The March 13, 1989, originated from a filament eruption on the Sun that ejected a high-speed CME, resulting in one of the most significant power grid failures in modern history. The ensuing geomagnetic disturbances induced (GICs) that overwhelmed the transmission system, causing a nine-hour blackout affecting six million people across and parts of the . The storm peaked with a Dst index of -589 nT, underscoring the direct link between solar eruptions and terrestrial infrastructure risks. The of October–November 2003 featured a sequence of multiple X-class solar flares and associated CMEs from AR 0486, producing some of the most intense of the space era. These events drove super-intense geomagnetic storms, with one reaching a Dst index of -383 nT, alongside solar energetic particle fluxes that elevated radiation levels to hazardous thresholds. Astronauts aboard the were compelled to shelter in protected areas to mitigate , as proton event intensities approached S4 (severe) levels for extended periods.

Modern and Extreme Events

One of the most notable near-misses in recent solar history occurred on , 2012, when a powerful coronal mass ejection (CME) erupted from AR1520 on the Sun's farside, narrowly avoiding a direct impact with . This Earth-directed event traveled at speeds exceeding 2,000 km/s, with the associated reaching approximately 3,000 km/s as it propagated through interplanetary space, arriving at the STEREO-A in just 19 hours. If it had struck , models indicate it would have triggered an extreme with a Dst index of around -1,200 nT, rivaling the intensity of the 1859 and potentially causing widespread technological disruptions. In May 2024, a series of fast and interacting CMEs from AR3664 produced the strongest since 2003, classified as G5 on the NOAA scale from May 10 to 12. These CMEs, traveling at speeds up to 1,300 km/s, arrived in rapid succession, with their compressed magnetic fields enhancing the storm's severity and leading to prolonged auroral displays visible at unusually low latitudes, including as far south as 21°N. The event also induced significant atmospheric expansion, resulting in increased satellite drag that affected low-Earth orbit assets, with drag levels rising by factors of up to 10 times normal and necessitating orbital adjustments for hundreds of satellites. Recent simulations in have highlighted the potential devastation of Carrington-scale CMEs, particularly in multi-CME complexes where successive ejections clear interplanetary , allowing subsequent events to accelerate and amplify impacts. European Space Agency (ESA) models from October predict that such a superstorm could increase drag by 400%, potentially destroying or deorbiting the entire constellation of low-Earth orbit through atmospheric heating and collision risks. These ENLIL-based simulations underscore the vulnerability of modern , estimating near-total loss in a direct hit scenario comparable to the event. A striking example of modern CME scale was observed on , , when a massive farside eruption from a complex produced a spectacular CME captured by NOAA's . Though non-Earth-directed, this event ejected billions of tons of plasma at high speeds, forming a vast halo-like structure visible in imagery, illustrating the immense energy release—estimated at over 10^32 ergs—possible during and the challenges in forecasting such remote ejections.

Stellar Analogues

CMEs in Other Stars

Observations of coronal mass ejections (CMEs) in stars other than the Sun rely primarily on indirect detection methods, as direct imaging is challenging due to the lack of spatial resolution for distant stars. In active stars such as RS CVn binaries, which are close binary systems with enhanced magnetic activity, CMEs are inferred from associated radio bursts and flares that indicate plasma ejections and events. These bursts, often in the decimeter to meter wavelength range, accompany flares and suggest shock waves driven by ejected material, similar to type II radio bursts observed in solar CMEs. Spectroscopic techniques have provided more direct evidence, particularly through Doppler shifts in emission lines that reveal outflowing plasma. In 2025, high-resolution far-ultraviolet (FUV) spectroscopy of the young Sun-like star EK Draconis captured the first multi-temperature signatures of a stellar CME, including hot plasma at approximately 100,000 K and cooler components indicative of a massive eruption following a . This event, with an estimated mass of about 10^17 grams, highlights the feasibility of detecting CMEs in young G-type stars via line profile asymmetries in spectra from instruments like the . In November 2025, astronomers confirmed the first coronal mass ejection from a star other than the Sun using radio and observations of the M dwarf StKM 1-1262, marking a breakthrough in direct detection. Analogous multi-temperature plasma ejections have been identified in stars, pre-main-sequence analogues to the early Sun, through combined and UV observations revealing dimming and outflow signatures during events. Frequency estimates for stellar CMEs vary by spectral type and activity level, with M-dwarfs exhibiting rates up to 10^3 to 10^4 times higher than the modern Sun due to their strong magnetic fields and frequent flaring. In these cool, low-mass stars, which dominate the , super-CMEs with kinetic energies ranging from 10^34 to 10^36 ergs occur regularly, often linked to exceeding 10^34 ergs in radiated energy. For comparison, solar CMEs typically release 10^30 to 10^32 ergs, underscoring the enhanced eruptive activity in more magnetically dynamic stars. Detection challenges persist, as most evidence is indirect and requires distinguishing CME signatures from other flare-related phenomena. Enhancements in H-alpha line profiles, such as red asymmetries from accelerating plasma, serve as proxies for outflows in M-dwarfs and active giants, but contamination from chromospheric activity complicates interpretation. Similarly, ultraviolet dimmings—temporary decreases in EUV —indicate coronal mass loss in K- and M-type stars, yet these are subtle and demand high-cadence photometry to confirm association with ejections. Advances in applied to spectral data are improving the identification of these Doppler signatures across stellar samples.

Implications for Exoplanetary Systems

Coronal mass ejections (CMEs) from active stars pose significant threats to the atmospheres of close-in exoplanets, particularly those orbiting in the of M dwarfs, by driving atmospheric erosion through high-energy particle impacts and enhanced escape processes. High-energy CMEs can strip volatiles such as and oxygen from planetary atmospheres, with the mass loss rate per event approximated as Ṁ ≈ (E_CME / E_bind) M_atm, where E_CME is the of the CME, E_bind is the of the atmosphere, and M_atm is the atmospheric mass; this process is most severe for planets with low escape velocities and weak . Studies indicate that for M dwarf exoplanets, frequent CME impacts—up to 0.5 to 5 per day—can lead to substantial atmospheric mass loss, potentially eroding entire envelopes over gigayears. Beyond physical stripping, stellar CMEs introduce biosphere threats by delivering lethal radiation doses and inducing ozone depletion in Earth-like atmospheres on exoplanets. The charged particles in CMEs can penetrate planetary magnetospheres, increasing levels that exceed survivable thresholds for surface life, with doses potentially reaching hundreds of times background levels during major events. In modeled Earth-analog atmospheres, CME-induced particle precipitation triggers NOx chemistry, depleting stratospheric by up to 50% or more, thereby allowing harmful UV to reach the surface and disrupt potential biological processes. The presence of frequent and energetic CMEs from active stars effectively reduces the width of habitable zones for exoplanets, as atmospheric retention becomes untenable closer to the star. For young, magnetically active stars similar to the early Sun, recent 2025 observations of massive CMEs from young solar-analog stars, such as EK Draconis, reveal that such events could have profoundly influenced planetary atmospheres in the early Solar System, providing clues to volatile delivery and loss mechanisms. Over stellar lifetimes, the cumulative effects of repeated CME-driven stripping can render worlds like Proxima b uninhabitable by progressively eroding protective atmospheres, with models suggesting that an unmagnetized Earth-like atmosphere around Proxima b could be fully eroded over approximately 100 million years due to combined and CME activity. This long-term erosion underscores the challenges for around flare-prone M dwarfs, where sustained particle bombardment limits the persistence of biospheres.

References

  1. https://www.jpl.nasa.gov/nmp/st5/SCIENCE/cme.html
  2. https://science.[nasa](/page/NASA).gov/sun/solar-storms-and-flares/
  3. https://pwg.gsfc.[nasa](/page/NASA).gov/istp/nicky/cme-chase.html
  4. https://cdaw.gsfc.[nasa](/page/NASA).gov/publications/gopal/gopal2016Geosci_lett.pdf
  5. https://solarscience.msfc.nasa.gov/CMEs.shtml
  6. https://hesperia.gsfc.nasa.gov/rhessi3/mission/science/the-impact-of-flares/index.html
  7. https://svs.gsfc.nasa.gov/31248/
  8. https://svs.gsfc.nasa.gov/5214/
  9. https://science.nasa.gov/blogs/parker-solar-probe/2023/09/15/parker-observes-powerful-coronal-mass-ejection-vacuum-up-interplanetary-dust/
  10. https://hesperia.gsfc.nasa.gov/sftheory/spaceweather.htm
  11. https://www.swpc.noaa.gov/phenomena/coronal-mass-ejections
  12. https://hesperia.gsfc.nasa.gov/summerschool/lectures/vourlidas/AV_intro2CMEs/lecture_CME_intro.pdf
  13. https://hesperia.gsfc.nasa.gov/sftheory/cme.htm
  14. https://cdaw.gsfc.nasa.gov/publications/gopal/gopal2006JAA27_243.pdf
  15. https://cdaw.gsfc.nasa.gov/publications/gopal/gopal2004.cme_review.pdf
  16. https://svs.gsfc.nasa.gov/11667/
  17. https://www.nasa.gov/image-article/what-solar-prominence/
  18. https://solarscience.msfc.nasa.gov/feature2.shtml
  19. https://srag.jsc.nasa.gov/spaceradiation/what/what.cfm
  20. https://www.cosmos.esa.int/web/solar-orbiter/-/science-nugget-multi-scale-structure-and-composition-of-icme-prominence-material-from-the-solar-wind-analyser-suite-1
  21. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002JA009672
  22. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020JA028380
  23. https://www.nature.com/articles/s41467-017-01207-x
  24. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017SW001767
  25. https://pmc.ncbi.nlm.nih.gov/articles/PMC6991970/
  26. https://link.springer.com/article/10.12942/lrsp-2011-1
  27. https://www.aanda.org/articles/aa/full_html/2013/05/aa19727-12/aa19727-12.html
  28. https://link.springer.com/content/pdf/10.1007/s11434-013-5669-6.pdf
  29. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014JA020848
  30. https://spacemath.gsfc.nasa.gov/sun/4Page17.pdf
  31. https://www.aanda.org/articles/aa/full_html/2016/12/aa27890-15/aa27890-15.html
  32. https://pmc.ncbi.nlm.nih.gov/articles/PMC5422629/
  33. https://solarscience.msfc.nasa.gov/papers/garyga/StretchingPaper.pdf
  34. https://link.aps.org/doi/10.1103/RevModPhys.82.603
  35. https://ntrs.nasa.gov/api/citations/20210000389/downloads/2021-674-ARTICLE-DEVORE-A%20Model%20for%20the%20Coupled%20Eruption%20of%20a%20Pseudostreamer%20and%20Helmet%20Streamer.pdf
  36. https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/1999JA900477
  37. https://www.researchgate.net/publication/386757494_CME_dynamics_using_STEREO_LASCO_observations_the_relative_importance_of_Lorentz_forces_and_solar_wind_drag
  38. https://link.springer.com/article/10.1007/s11214-017-0462-5
  39. https://www.aanda.org/articles/aa/full_html/2024/03/aa47927-23/aa47927-23.html
  40. https://pmc.ncbi.nlm.nih.gov/articles/PMC12304066/
  41. https://arxiv.org/abs/1607.05961
  42. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2017JA024369
  43. https://link.springer.com/article/10.1007/s11207-017-1129-9
  44. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015JA021415
  45. https://iopscience.iop.org/article/10.3847/1538-4357/ab543e
  46. https://iopscience.iop.org/article/10.3847/1538-4357/aa8ef9
  47. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002JA009817
  48. https://iopscience.iop.org/article/10.1086/523893/fulltext/
  49. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015JA021076
  50. https://ntrs.nasa.gov/citations/20080002231
  51. https://iopscience.iop.org/article/10.3847/1538-4357/aa8e49
  52. https://ntrs.nasa.gov/api/citations/20070014866/downloads/20070014866.pdf
  53. https://www.aanda.org/articles/aa/full_html/2020/03/aa36664-19/aa36664-19.html
  54. https://iopscience.iop.org/article/10.1086/307101/fulltext/
  55. https://www.frontiersin.org/journals/astronomy-and-space-sciences/articles/10.3389/fspas.2021.631582/full
  56. https://www.researchgate.net/profile/Russell-Howard-5/publication/323819677_Evolution_of_CME_Mass_in_the_Corona/links/5b11d7400f7e9b498102e71e/Evolution-of-CME-Mass-in-the-Corona.pdf
  57. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2004JA010698
  58. https://iopscience.iop.org/article/10.3847/1538-4357/aa697c
  59. https://www.aanda.org/articles/aa/full_html/2022/04/aa42942-21/aa42942-21.html
  60. https://ntrs.nasa.gov/api/citations/20210017499/downloads/2021_Frontiers_published.pdf
  61. https://iopscience.iop.org/article/10.3847/1538-4357/ab371b
  62. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2000JA002228
  63. https://iopscience.iop.org/article/10.3847/1538-4357/ac7ff6
  64. https://www.nature.com/articles/s41550-025-02691-8
  65. https://iopscience.iop.org/article/10.3847/1538-4365/ab2bfe
  66. https://iopscience.iop.org/article/10.3847/1538-4357/acab5e
  67. https://www.aanda.org/articles/aa/full_html/2023/11/aa46907-23/aa46907-23.html
  68. https://ntrs.nasa.gov/api/citations/20230010368/downloads/Temmer_CME.pdf
  69. https://ntrs.nasa.gov/api/citations/20230003476/downloads/Alzate_2023_ApJ_945_116%2520%281%29.pdf
  70. https://iopscience.iop.org/article/10.1088/0004-637X/691/2/1222
  71. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2003JA010282
  72. https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/96JA02037
  73. https://ui.adsabs.harvard.edu/abs/2003SoPh..218..261A/abstract
  74. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017JA024035
  75. https://www.science.org/doi/10.1126/sciadv.aau7004
  76. https://arxiv.org/abs/1212.4014
  77. https://www.sciencedirect.com/science/article/abs/pii/S1364682620302674
  78. https://www.swsc-journal.org/articles/swsc/full_html/2018/01/swsc180013/swsc180013.html
  79. https://www.researchgate.net/publication/274319819_On_the_Statistical_Relationship_Between_CME_Speed_and_Soft_X-Ray_Flux_and_Fluence_of_the_Associated_Flare
  80. https://iopscience.iop.org/article/10.1088/0004-637X/732/2/87
  81. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017JA024710
  82. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012JA017904
  83. https://link.springer.com/article/10.1007/BF00173674
  84. https://www.sciencedirect.com/science/article/abs/pii/S0273117725004624
  85. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014JA019831
  86. https://link.springer.com/article/10.1007/s11214-012-9941-x
  87. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020SW002661
  88. https://www.sciencedirect.com/science/article/pii/S2405844024067562
  89. https://angeo.copernicus.org/articles/39/687/2021/
  90. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2010JA015774
  91. https://www.sciencedirect.com/science/article/pii/S0273117724008500
  92. https://www.ferc.gov/sites/default/files/2020-05/ferc_meta-r-319.pdf
  93. https://www.pnnl.gov/main/publications/external/technical_reports/pnnl-21033.pdf
  94. https://science.nasa.gov/sun/solar-storms-and-flares/
  95. https://www.unoosa.org/documents/pdf/psa/activities/2024/ISWI2024/ISWI2024_11_01.pdf
  96. https://earth-planets-space.springeropen.com/articles/10.1186/s40623-020-01345-5
  97. https://www.sciencedirect.com/science/article/abs/pii/S0273117725001115
  98. https://spacenews.com/solar-flares-in-may-2024-revealed-earths-vulnerability-to-space-weather/
  99. https://www.swpc.noaa.gov/news/g4-severe-watch-effect-12-november
  100. https://www.nature.com/articles/s41598-019-38918-8
  101. https://www.wtwco.com/en-nz/insights/2025/02/the-gray-swan-in-our-sky-multibillion-dollar-threat-of-solar-flares
  102. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023SW003805
  103. https://www.sciencedirect.com/science/article/pii/S1364682600000985
  104. https://iopscience.iop.org/article/10.1088/0004-637X/790/1/25
  105. https://www.swsc-journal.org/articles/swsc/full_html/2018/01/swsc170032/swsc170032.html
  106. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2024SW003951
  107. https://www.janss.kr/archive/view_article?pid=jass-41-3-171
  108. https://svs.gsfc.nasa.gov/5435/
  109. https://ntrs.nasa.gov/api/citations/20150011136/downloads/20150011136.pdf
  110. https://geoscienceletters.springeropen.com/articles/10.1186/s40562-016-0039-2
  111. https://www.researchgate.net/publication/267779170_A_Historical_Perspective_on_Coronal_Mass_Ejections
  112. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2005EO110004
  113. https://pmc.ncbi.nlm.nih.gov/articles/PMC6956910/
  114. https://www.researchgate.net/publication/361737192_Analysis_of_Voyager_1_and_Voyager_2_in_situ_CME_observations
  115. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016JA022598
  116. https://www.aanda.org/articles/aa/full_html/2023/07/aa44015-22/aa44015-22.html
  117. https://cdaw.gsfc.nasa.gov/CME_list/
  118. https://www.swpc.noaa.gov/products/lasco-coronagraph
  119. https://www.jhuapl.edu/destinations/missions/stereo
  120. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/jgra.50101
  121. https://ntrs.nasa.gov/api/citations/20050212156/downloads/20050212156.pdf
  122. https://www.nesdis.noaa.gov/news/when-solar-storms-attack-space-weather-and-our-infrastructure
  123. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002JA009504
  124. https://www.swsc-journal.org/articles/swsc/full_html/2024/01/swsc230032/swsc230032.html
  125. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018SW002024
  126. https://epact2.gsfc.nasa.gov/don/Variations.pdf
  127. https://nap.nationalacademies.org/read/10249/chapter/11
  128. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019sw002278
  129. https://www.scientificamerican.com/article/geomagnetic-storm-march-13-1989-extreme-space-weather/
  130. https://cdaw.gsfc.nasa.gov/publications/gopal/gopal2006SEE_20.pdf
  131. https://arxiv.org/pdf/1709.03165
  132. https://www.ncei.noaa.gov/news/great-halloween-solar-storm-2003
  133. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/swe.20097
  134. https://iopscience.iop.org/article/10.1088/0004-637X/770/1/38
  135. https://science.nasa.gov/science-research/planetary-science/23jul_superstorm/
  136. https://www.swpc.noaa.gov/news/severe-and-extreme-g4-g5-geomagnetic-storms-likely-12-may-2024
  137. https://arxiv.org/html/2406.08617v1
  138. https://svs.gsfc.nasa.gov/5375/
  139. https://www.helsinkitimes.fi/themes/themes/science-and-technology/28143-scientists-prepare-for-solar-storm-that-could-wipe-out-satellites.html
  140. https://www.livescience.com/space/the-sun/the-next-carrington-level-solar-superstorm-could-wipe-out-all-our-satellites-new-simulations-reveal
  141. https://www.space.com/astronomy/sun/suns-far-side-erupts-in-satellite-image-space-photo-of-the-day-for-oct-29-2025
  142. https://adsabs.harvard.edu/full/2004IAUS..219..145B
  143. https://link.springer.com/article/10.1007/s41116-024-00039-4
  144. https://arxiv.org/html/2504.02469v1
  145. https://www.sci.news/astronomy/coronal-mass-ejections-young-sun-like-star-14312.html
  146. https://www.esa.int/Science_Exploration/Space_Science/XMM-Newton/First_confirmed_sighting_of_explosive_burst_on_nearby_star
  147. https://arxiv.org/html/2510.22112v1
  148. https://academic.oup.com/mnras/article/472/1/876/4060734
  149. https://www.science.org/doi/10.1126/sciadv.abi9743
  150. http://www2.lowell.edu/workshops/coolstars18/articles/031-Airapetian%2B_CS18.pdf
  151. https://iopscience.iop.org/article/10.3847/1538-4357/ad1928
  152. https://www.nature.com/articles/s41550-021-01532-8
  153. https://arxiv.org/abs/2401.07588
  154. https://iopscience.iop.org/article/10.3847/0004-637X/826/2/195
  155. https://academic.oup.com/mnras/article/532/2/1486/7688464
  156. https://www.researchgate.net/publication/364954867_3D_modelling_of_the_impact_of_stellar_activity_on_tidally_locked_terrestrial_exoplanets_atmospheric_composition_and_habitability
  157. https://www.nature.com/articles/s41550-025-02707-3
  158. https://www.researchgate.net/publication/313712531_Is_Proxima_Centauri_b_habitable_--_A_study_of_atmospheric_loss
  159. https://science.nasa.gov/universe/exoplanets/an-earth-like-atmosphere-may-not-survive-proxima-bs-orbit/
Add your contribution
Related Hubs
Contribute something
User Avatar
No comments yet.