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Beta Canum Venaticorum
Beta Canum Venaticorum
Beta Canum Venaticorum
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β Canum Venaticorum
Location of β Canum Venaticorum (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Canes Venatici
Right ascension 12h 33m 44.54425s[1]
Declination +41° 21′ 26.9214″[1]
Apparent magnitude (V) 4.25[2]
Characteristics
Spectral type G0 V[3]
U−B color index 0.04[4]
B−V color index 0.58[4]
Astrometry
Radial velocity (Rv)+6.15±0.12[1] km/s
Proper motion (μ) RA: −704.702[1] mas/yr
Dec.: +292.155[1] mas/yr
Parallax (π)118.0266±0.1530 mas[1]
Distance27.63 ± 0.04 ly
(8.47 ± 0.01 pc)
Absolute magnitude (MV)4.64[5]
Details
Mass0.97±0.04[6] M☉
Radius1.03±0.03[7] R☉
Luminosity1.254±0.009[8] L☉
Surface gravity (log g)4.41±0.04[8] cgs
Temperature6,013±91[8] K
Metallicity [Fe/H]−0.2±0.01[8] dex
Rotational velocity (v sin i)2.9±0.4[9] km/s
Age3.4[6] to 7.1[5] Gyr
Other designations
Chara, β CVn, 8 CVn, BD+42 2321, FK5 470, GJ 475, HD 109358, HIP 61317, HR 4785, SAO 44230, NGC 4530[10]
Database references
SIMBADdata
ARICNSdata

Beta Canum Venaticorum is the second-brightest star in the northern constellation of Canes Venatici. Its name is a Bayer designation; it has the proper name Chara, pronounced /ˈkɛərə/.[11][12] This is a nearby solar-type star, located 27.6 light-years (8.5 parsecs) distant based on its parallax. The star is faintly visible to the naked eye, at an apparent magnitude of +4.25. Along with the brighter star Cor Caroli, the pair form the "southern dog" in this constellation that represents hunting dogs.

Nomenclature

[edit]

β Canum Venaticorum (Latinised to Beta Canum Venaticorum) is the star's Bayer designation, which is abbreviated Beta CVn or β CVn. It has the Flamsteed designation 8 Canum Venaticorum.[10] The star was listed in the New General Catalogue as NGC 4530.[13][14]

The traditional name Chara was originally applied to the "southern dog", but it later became used specifically to refer to Beta Canum Venaticorum. Chara (χαρά) means 'joy' in Greek[15] but ‍‘dear’ ‍or ‍’beloved’ in Latin.[16] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[17] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[18] included a table of the first two batches of names approved by the WGSN; which included Chara for this star.

In Chinese, 常陳 (Cháng Chén), meaning Imperial Guards, refers to an asterism consisting of Beta Canum Venaticorum, Alpha Canum Venaticorum, 10 Canum Venaticorum, 6 Canum Venaticorum, 2 Canum Venaticorum, and 67 Ursae Majoris.[19] Consequently, the Chinese name for Beta Canum Venaticorum itself is 常陳四 (Cháng Chén sì, English: the Fourth Star of Imperial Guards.)[20]

Characteristics

[edit]

Beta CVn has a stellar classification of G0 V, and so is a G-type main-sequence star. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[21] The spectrum of this star shows a very weak emission line of singly ionized calcium (Ca II) from the chromosphere, making it a useful reference star for a reference spectrum to compare with other stars in a similar spectral category.[22] (The Ca-II emission lines are readily accessible and can be used to measure the level of activity in a star's chromosphere.)

Beta CVn is considered to be slightly metal-poor,[8] which means it has a somewhat lower portion of elements heavier than helium when compared to the Sun. In terms of mass, age and evolutionary status, however, this star is very similar to the Sun.[23] As a result, it has been called a solar analog. It is about 3% less massive than the Sun,[2] with a radius 3% larger than the Sun's and 25% greater luminosity.[7][8]

The components of this star's space velocity are (U, V, W) = (–25, 0, +2) km/s.[23] In the past it was suggested that it may be a spectroscopic binary. However, further analysis of the data does not seem to bear that out.[24] In addition, a 2005 search for a brown dwarf in orbit around this star failed to discover any such companion, at least down to the sensitivity limit of the instrument used.[25]

Habitability

[edit]

In 2006, astronomer Margaret Turnbull labeled Beta CVn as the top stellar system candidate to search for extraterrestrial life forms.[26] Because of its solar-type properties, astrobiologists have listed it among the most astrobiologically interesting stars within 10 parsecs of the Sun.[23] However, as of 2009, this star is not known to host planets.[2]

See also

[edit]

References

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

Beta Canum Venaticorum

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from Grokipedia
Beta Canum Venaticorum (β CVn), also known by its proper name Chara, is a G0V main-sequence star located in the northern constellation of Canes Venaticorum, approximately 27.5 light-years (8.46 parsecs) from the Sun. It is the second-brightest star in its constellation, with an apparent visual magnitude of 4.25, rendering it faintly visible to the in clear, dark skies, and it serves as a prominent due to its close physical resemblance to the Sun. Chara exhibits a surface temperature of about 5880 , a luminosity 18% greater than the Sun's, and dimensions very similar to the solar ones, including a mass near 1 solar mass and a radius roughly 4% larger. The star's metallicity is notably lower than the Sun's, with iron abundance at around 60% of solar levels, and it is estimated to be older, with an age of approximately 7 billion years (ranging from 4.1 to 12 billion years). Positioned at right ascension 12h 33m 44.5s and declination +41° 21′ 27″ (J2000 epoch), it displays significant proper motion—about 704 mas/yr in right ascension and 292 mas/yr in declination—and a radial velocity of +6.3 km/s relative to the Sun. As a suspected double or multiple system, Chara may host an unseen companion, potentially orbiting every 6.65 years at a separation of about 3 AU, though this remains unconfirmed by direct observation. The primary star shows signs of magnetic activity, including emission from a hot corona and a rotation period of less than 17 days, with a surface speed of at least 3 km/s. No planets have been detected around it, but its solar-like characteristics have drawn interest in astrobiology, classifying it as one of the nearest "biostars" suitable for studying potential habitability zones similar to our own.

Nomenclature

Designations

Beta Canum Venaticorum holds the β Canum Venaticorum (β CVn), assigned as the second-brightest star in the constellation according to the system introduced by in 1603. It also bears the Flamsteed designation 8 Canum Venaticorum, from John Flamsteed's 1725 Historia Coelestis Britannica, which numbers stars sequentially by within each constellation. In contemporary astronomical catalogs, the star is identified as HD 109358 in the Henry Draper Catalogue of stellar spectra, HIP 61317 in the astrometric catalog, and Gaia DR3 1534011998572555776 in the third data release of the mission. The approved the proper name Chara for β Canum Venaticorum on 20 July 2016 through its on Star Names.

Etymology and Cultural Names

The proper name Chara for Beta Canum Venaticorum originates from the work of Polish astronomer , who introduced the constellation Canes Venaticorum in his 1690 star atlas Firmamentum Sobiescianum sive Uranographia. Hevelius designated the star as the head of the southern dog in the pair of hunting dogs accompanying , naming it Chara to represent the female hound, with the term deriving from Greek chairein meaning "joy" or from Latin cara meaning "dear" or "beloved". This name was later formalized for the individual star by Richard Hinckley Allen in his 1899 compendium Star Names: Their Lore and Meaning, distinguishing it from the broader application to the southern dog figure that initially included Alpha Canum Venaticorum (). In 2016, the () on Star Names officially approved Chara as the proper name for Beta Canum Venaticorum, standardizing it for astronomical use. Within the constellation Canes Venaticorum, Beta Canum Venaticorum serves as the principal star of the "southern dog," positioned as the companion to the brighter northern dog marked by , symbolizing the leashed hounds of in Hevelius's depiction. The constellation itself lacks deep roots in ancient mythology, having been created in the late without significant pre-existing cultural narratives beyond this modern hunting motif. In traditional , Beta Canum Venaticorum is known as 常陳四 (Cháng Chén sì), translating to "Fourth Star of the Imperial Guards," as it forms part of the Cháng Chén asterism representing celestial guardians in the northern sky. This naming convention reflects its position within a four-star pattern associated with imperial protection in ancient Chinese star catalogs.

Location and Observability

Position and Coordinates

Beta Canum Venaticorum occupies a prominent position within the constellation , serving as its second-brightest star after Alpha Canum Venaticorum (). It is situated near the hind paw of the "southern" hound in the traditional asterism of the Hunting Dogs, which Hevelius introduced in to represent the two dogs held on a by . The star's equatorial coordinates in the J2000 epoch are 12h 33m 44s.544 and +41° 21′ 26″.92. These positions place it in the , facilitating observation from mid-northern latitudes during spring evenings. Its galactic coordinates are l = 136.13° and b = +75.31°, indicating a location high above the in the direction of the northern galactic hemisphere. Beta Canum Venaticorum lies at a distance of 27.63 ± 0.04 light-years (8.47 ± 0.01 parsecs) from the Solar System. This measurement derives from a trigonometric parallax of 117.95 ± 0.18 milliarcseconds obtained by the Gaia spacecraft in its Data Release 3 (DR3), which provides the most precise astrometric data available for this nearby star. The high parallax value confirms its proximity, making it one of the closer G-type main-sequence stars to Earth.

Visibility from Earth

Beta Canum Venaticorum has an apparent visual magnitude of 4.25, making it faintly visible to the under good observing conditions with , though it may require in areas with . The is observable from latitudes between 0° and 90° N, appearing highest in the northern during spring evenings from to , when the constellation Canes Venaticorum is well-placed for viewing after sunset. It culminates at or near midnight in late May for observers in the mid-northern latitudes, providing optimal viewing opportunities free from horizon obstruction. Beta Canum Venaticorum exhibits stable brightness with no significant variability, classified as a non-variable star despite minor suspected fluctuations below detectable thresholds for amateur observers.

Stellar Characteristics

Physical Parameters

Beta Canum Venaticorum is a main-sequence star of spectral type G0 V, classifying it as a G-type dwarf and a close with properties similar to those of the Sun. Its mass is estimated at 0.97 ± 0.04 solar masses (M⊙), indicating a star slightly less massive than the Sun but still within the typical range for G-type main-sequence stars. The radius measures 1.03 ± 0.03 solar radii (R⊙), determined through interferometric observations that provide direct measurements combined with precise estimates. The star's luminosity is 1.254 ± 0.009 solar luminosities (L⊙), reflecting its slightly enhanced energy output compared to the Sun due to the combined effects of its temperature and size. Its effective temperature is 6,013 ± 91 K, giving the star a yellowish-white appearance consistent with G-type stars, as observed in visible light spectra. The absolute visual magnitude is 4.64, which, when combined with its apparent magnitude of approximately 4.25, confirms its distance of about 27.6 light-years based on Gaia parallax measurements. Surface gravity is characterized by log g = 4.38 (in cgs units), a value typical for main-sequence dwarfs of this spectral type and indicative of the star's evolutionary position on the Hertzsprung-Russell diagram. These parameters collectively position Beta Canum Venaticorum as a stable, Sun-like star suitable for studies of solar analogs and potential planetary systems.

Spectrum and Composition

Beta Canum Venaticorum exhibits a solar-like characteristic of a G0 V main-sequence star, with prominent Balmer absorption lines in the blue region and strong metal lines dominated by neutral iron-group elements across the . The classification is based on the relative strengths of these features, including the broad Hβ and Hγ lines indicating a around 5900 , alongside calcium K-line and G-band features typical of late G dwarfs. Detailed spectroscopic analysis reveals a metallicity of [Fe/H] = −0.22 ± 0.04 dex, rendering the star slightly metal-poor relative to the Sun. This value is derived from equivalent widths of iron lines using model atmosphere fitting, confirming a consistent abundance pattern across multiple indicators. Abundances of key elements show mild enhancements in alpha-process isotopes, such as [Mg/H] = −0.13 ± 0.06 dex and [Ca/H] = −0.21 ± 0.11 dex, yielding [α/Fe] ratios near +0.05 to +0.10 dex—typical for thin-disk population stars at this metallicity level, reflecting contributions from core-collapse supernovae in the Galactic disk. The star displays no significant chemical peculiarities, with lithium abundance log ε(Li) = 1.49 ± 0.10, consistent with standard depletion levels for a of comparable age and activity, as measured from the 6708 Å resonance doublet.

Kinematics and Motion

Beta Canum Venaticorum exhibits substantial motion through space, characteristic of nearby stars in the solar neighborhood. Its is notably high, with components of −704.702 ± 0.126 mas/yr in and +292.155 ± 0.172 mas/yr in , as measured by the mission's second data release. This rapid transverse motion across the sky is typical for stars at a distance of about 8.5 parsecs, yielding a tangential of approximately 30.6 km/s relative to the Sun. The star's , measured from high-resolution optical , is +6.268 ± 0.0004 km/s, indicating it is receding from the Solar System at a modest pace. Combined with the and distance, these kinematic parameters describe Beta Canum Venaticorum's path through the , consistent with membership in the population and a relatively stable galactocentric .

Evolutionary Properties

Age

The age of Beta Canum Venaticorum is estimated to be between 2.5 and 7.1 billion years, derived from complementary methods including gyrochronology and isochrone fitting. No direct rotation period has been measured, but the rotational velocity of v sin i = 3.15 km/s implies an upper limit on the period of approximately 18 days (assuming equatorial view and radius ≈1.03 R⊙). Gyrochronology, using relations calibrated for solar-type stars (e.g., assuming P ≈15–20 days), provides a lower bound near 2.5 Gyr, reflecting relatively rapid spin for a post-solar G dwarf. Isochrone fitting offers an independent upper limit of around 7.1 Gyr by placing the star on theoretical evolutionary tracks in the Hertzsprung-Russell diagram, incorporating its effective temperature of 6013±91 K, luminosity of 1.25 L⊙, and metallicity [Fe/H] = −0.20±0.01 dex. These models, such as those from the Yale-Yonsei or Padova series, account for the star's position on the main sequence but introduce uncertainties due to its slightly metal-poor composition, which can shift isochrones and broaden the age range by up to 20–30%. This estimated age range positions Beta Canum Venaticorum as roughly coeval with or slightly older than the Sun, whose age is 4.6 Gyr based on meteoritic and helioseismology. For G dwarfs, such ages are typical, spanning the middle to late main-sequence phase where activity levels have declined, as evidenced by the star's modest chromospheric emission. The slight metal deficiency relative to solar values ([Fe/H] = 0 dex) further complicates precise modeling, as lower slows evolutionary timescales and increases helium abundance effects in isochrones.

Evolutionary Stage

Beta Canum Venaticorum is a G0V main-sequence undergoing hydrogen core fusion, placing it on the main-sequence branch of the Hertzsprung-Russell diagram near the Sun but slightly hotter and more luminous. With an estimated age of ≈5 Gyr (midpoint of revised range), it is approximately 65% through its main-sequence lifetime of about 7.5–8 Gyr for a of its mass (1.04 M⊙). The exhibits a slow projected rotational velocity of v sin i = 3.15 km/s, characteristic of older solar-type stars where magnetic braking has slowed the over billions of years, consistent with its age. This slow contributes to its low level of magnetic activity. Chromospheric activity is minimal, with Ca II H&K emission levels (log R'HK = −4.92) comparable to those of the quiet Sun, indicating subdued stellar winds and no observed flares. In the coming 2.5–3 Gyr, as core hydrogen depletion continues, the star will exhaust its fuel supply and ascend the red giant branch, expanding and cooling while fusing helium in a shell.

Potential Companions

Searches for Stellar Companions

High-resolution imaging surveys have searched for stellar and substellar companions to Beta Canum Venaticorum, focusing on wide separations where direct detection is feasible. Ground-based adaptive optics observations using the ShaneAO system at Lick Observatory (2015–2018) and the PHARO instrument at Palomar Observatory (2016–2017) in the near-infrared Ks band detected no companions. These surveys achieved near-complete sensitivity for companions more massive than 0.09 M⊙M_\odot within projected separations of up to 100 AU, effectively ruling out massive brown dwarfs or low-mass stars in this range. A dedicated 2005 near-infrared survey of nearby Sun-like stars, including targets similar to Beta Canum Venaticorum, also yielded no detections of companions within 100 AU, down to sensitivities of approximately 50 MJupM_\mathrm{Jup} at separations beyond 50 AU. This effort, part of broader programs to probe the "brown dwarf desert," reinforced the absence of substellar objects at intermediate orbital distances for G-type dwarfs like Beta Canum Venaticorum. Combined with HST imaging constraints from general surveys of nearby field stars, no close visual binaries have been identified, consistent with the star hosting no resolved companions at angular separations greater than 0".1 (approximately 1 AU at its distance). Radial velocity monitoring provides complementary constraints on closer companions. A 20-year campaign using the Keck I telescope's HIRES spectrometer and the Automated Planet Finder at collected 235 high-precision measurements, revealing RV stability to within 10 m/s with no significant periodic signals. This rules out massive companions causing detectable perturbations, including no Jupiter-mass or higher objects in orbits shorter than 10 years; specific upper limits include minimum masses below 0.23 MJupM_\mathrm{Jup} for periods under 100 days and below 2.3 MJupM_\mathrm{Jup} for periods under 10 years. Extending to 20-year periods, the limit is 9.5 MJupM_\mathrm{Jup}. Overall, these results establish upper limits of no companions more massive than 0.08 M⊙M_\odot within 50 AU, supporting the classification of Beta Canum Venaticorum as a single star suitable for studies.

Constraints on Planets

As of November 2025, no exoplanets have been confirmed orbiting Beta Canum Venaticorum through (RV), transit photometry, or direct imaging techniques. Precision RV monitoring of the star, spanning over 20 years from 1998 to 2018 using the Keck High Resolution Echelle Spectrometer and the Automated Planet Finder, achieved a root-mean-square precision of 3.7 m s⁻¹ with no significant periodic signals detected. This dataset rules out Jupiter-mass with orbital periods up to several years and sets upper limits on lower-mass companions, excluding more massive than approximately 3 masses (M⊕) in inner orbits with periods shorter than 100 days. Transit surveys, including observations from NASA's (TESS), have monitored Beta Canum Venaticorum but yielded no detectable transit signals, constraining the presence of large planets in short-period orbits (periods ≲ 30 days) with radii greater than about 2 radii. Astrometric data from the mission's Early Data Release 3 (EDR3) and subsequent analyses show no significant acceleration for the star (0.83 ± 0.56 mas yr⁻²), providing constraints on outer companions. These observations limit the existence of planets more massive than 10 M⊕ at separations beyond 10 AU, with general sensitivity reaching ~85% detection efficiency for 2 Jupiter-mass planets between 4 and 10 AU in similar systems. Early RV searches in the targeted Beta Canum Venaticorum due to its close resemblance to the Sun as a G0V , motivating efforts to probe for potentially habitable worlds similar to the Solar System.

Habitability Potential

The (HZ) of Beta Canum Venaticorum defines the orbital region where conditions might allow liquid water to persist on a , assuming Earth-like atmospheres and no significant effects. For this G0V star with a of 1.151 ± 0.018 L_⊙, the conservative HZ boundaries—delimited by the recent and early Mars limits—are estimated at 1.03 AU (inner edge) to 1.82 AU (outer edge). These limits are derived from updated radiative-convective climate models that account for atmospheric absorption and stellar . The incident stellar flux within the HZ of Beta Canum Venaticorum closely mirrors that of the Solar System, where at 1 AU receives approximately 1.36 × 10^6 erg s^{-1} cm^{-2}. Adjustments for the star's shift the HZ outward relative to the Sun's, scaling the boundaries proportionally to the of the luminosity ratio, as per standard HZ formulations. Optimistic HZ estimates, extending from the moist limit to the maximum greenhouse boundary, span 0.81 AU to 1.92 AU, broadening the potential range for habitable conditions under more permissive atmospheric scenarios. Long-term dynamical stability within the HZ supports systems of up to approximately six Earth-mass , based on N-body simulations that incorporate mean-motion resonances and the absence of detected giant companions interior to 10 AU (with upper limits exceeding 300 M_⊕ ruled out). The star's low eccentricity and single-star nature enhance stability, allowing packed configurations without close encounters over gigayear timescales for stellar masses around 0.85 M_⊙. In 2006, astronomer Margaret Turnbull identified Beta Canum Venaticorum as the top stellar candidate for hosting habitable exoplanets in her HabCat, prioritizing it for astrobiological and SETI investigations due to its estimated age of 3–7 billion years, near-solar sufficient for formation, low chromospheric activity, and position in the thin galactic disk suggesting a stable orbital history. Key selection criteria focused on fostering a stable environment conducive to , including minimal stellar variability and slow rotational (around 3 km/s, comparable to the Sun's), which reduce the risk of harmful flares or rapid changes in planetary insolation; thin-disk membership ensures avoidance of high-velocity halo or thick-disk with disruptive ; and its proximity at 27.3 light-years enables efficient and potential access for future interstellar probes. This prioritization led to targeted radio observations in SETI programs, including those with the in the 2000s based on Turnbull's shortlist, spanning frequencies for potential technosignatures; however, no artificial signals were detected in these searches. Beta Canum Venaticorum continues to hold promise in the era for direct imaging of planets, should they exist, owing to its brightness and solar-like properties that facilitate high-contrast observations despite the challenges of inner-system debris stability.

References

  1. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=Beta+Canum+Venaticorum
  2. http://stars.astro.illinois.edu/sow/chara.html
  3. https://pubmed.ncbi.nlm.nih.gov/16689649/
  4. https://astrobiology.nasa.gov/news/how-many-habitable-zone-planets-can-orbit-a-host-star/
  5. https://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf
  6. http://www.ianridpath.com/startales/canesvenatici.html
  7. https://stars.astro.illinois.edu/sow/chara.html
  8. http://www.ianridpath.com/starnames.html
  9. https://www.constellation-guide.com/constellation-list/canes-venatici-constellation/
  10. https://www.simbad.u-strasbg.fr/simbad/sim-id?Ident=beta+Canum+Venaticorum
  11. http://simbad.cds.unistra.fr/simbad/sim-basic?Ident=bet+CVn
  12. https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=I/355/gaiadr3&recno=1534011998572555776
  13. http://simbad.cds.unistra.fr/simbad/sim-id?Ident=bet+CVn
  14. https://theskylive.com/sky/stars/chara-beta-canum-venaticorum-star
  15. https://theskylive.com/sky/constellations/canes_venatici-constellation
  16. http://www.alcyone.de/SIT/mainstars/SIT000395.htm
  17. https://ui.adsabs.harvard.edu/abs/2018AJ....155...30B/abstract
  18. https://www.aanda.org/articles/aa/pdf/2011/02/aa15907-10.pdf
  19. https://iopscience.iop.org/article/10.1088/0004-637X/736/2/87
  20. https://ui.adsabs.harvard.edu/abs/2014ApJ...780..159E/abstract
  21. https://ui.adsabs.harvard.edu/abs/2025A&A...698A..93J/abstract
  22. https://iopscience.iop.org/article/10.3847/1538-3881/abd639
  23. https://iopscience.iop.org/article/10.1086/432604
  24. https://iopscience.iop.org/article/10.3847/1538-3881/ab9ffe
  25. https://iopscience.iop.org/article/10.3847/1538-3881/ade442
  26. https://www.space.com/2072-top-10-list-habitable-stars-guide-search.html
  27. https://www.newscientist.com/article/mg18925403-600-star-candidates-for-life-beyond-earth/
  28. https://iopscience.iop.org/article/10.1086/345779/fulltext/
  29. https://chview.nova.org/solcom/stars/chara.htm
  30. https://www.nbcnews.com/id/wbna11427824
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