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Antlia
Constellation
Antlia
List of stars in Antlia
AbbreviationAnt
GenitiveAntliae
Pronunciation/ˈæntliə/, genitive /-lii/
Symbolismthe Air Pump[1]
Right ascension09h 27m 05.1837s–11h 05m 55.0471s[2]
Declination−24.5425186°–−40.4246216°[2]
Area239 sq. deg. (62nd)
Main stars3
Bayer/Flamsteed
stars		9
Stars brighter than 3.00m0
Stars within 10.00 pc (32.62 ly)2
Brightest starα Ant (4.25m)
Nearest starDEN 1048-3956[3]
Messier objects0
Meteor showersNone
Bordering
constellations		Hydra
Pyxis
Vela
Centaurus
Visible at latitudes between +45° and −90°.
Best visible at 21:00 (9 p.m.) during the month of April.

Antlia (/ˈæntliə/; from Ancient Greek ἀντλία) is a constellation in the Southern Celestial Hemisphere. Its name means "pump" in Latin and Greek; it represents an air pump. Originally Antlia Pneumatica, the constellation was established by Nicolas-Louis de Lacaille in the 18th century. Its non-specific (single-word) name, already in limited use, was preferred by John Herschel then welcomed by the astronomic community which officially accepted this. North of stars forming some of the sails of the ship Argo Navis (the constellation Vela), Antlia is completely visible from latitudes south of 49 degrees north.

Antlia is a faint constellation; its brightest star is Alpha Antliae, an orange giant that is a suspected variable star, ranging between apparent magnitudes 4.22 and 4.29. S Antliae is an eclipsing binary star system, changing in brightness as one star passes in front of the other. Sharing a common envelope, the stars are so close they will one day merge to form a single star. Two star systems with known exoplanets, HD 93083 and WASP-66, lie within Antlia, as do NGC 2997, a spiral galaxy, and the Antlia Dwarf Galaxy.

History

[edit]
Johann Bode's depiction of Antlia as a double-cylinder air pump

The French astronomer Nicolas-Louis de Lacaille first described the constellation in French as la Machine Pneumatique (the Pneumatic Machine) in 1751–52,[4][5] commemorating the air pump invented by the French physicist Denis Papin.[6] De Lacaille had observed and catalogued almost 10,000 southern stars during a two-year stay at the Cape of Good Hope, devising fourteen new constellations in uncharted regions of the Southern Celestial Hemisphere not visible from Europe. He named all but one in honour of instruments that symbolised the Age of Enlightenment.[a][7] Lacaille depicted Antlia as a single-cylinder vacuum pump used in Papin's initial experiments, while German astronomer Johann Bode chose the more advanced double-cylinder version.[6] Lacaille Latinised the name to Antlia pneumatica on his 1763 chart. English astronomer John Herschel proposed shrinking the name to one word in 1844, noting that Lacaille himself had abbreviated his constellations thus on occasion.[8] This was universally adopted.[9] The International Astronomical Union adopted it as one of the 88 modern constellations in 1922.[10]

Although visible to the Ancient Greeks, Antlia's stars were too faint to have been commonly recognised as a figurative object, or part of one, in ancient asterisms.[6] The stars that now comprise Antlia are in a zone of the sky associated with the asterism/old constellation Argo Navis, the ship, the Argo, of the Argonauts, in its latter centuries. This, due to its immense size, was split into hull, poop deck and sails by Lacaille in 1763.[11][12] Ridpath reports that due to their faintness, the stars of Antlia did not make up part of the classical depiction of Argo Navis.[13]

In non-Western astronomy

[edit]

Chinese astronomers were able to view what is modern Antlia from their latitudes, and incorporated its stars into two different constellations. Several stars in the southern part of Antlia were a portion of "Dong'ou", which represented an area in southern China.[6] Furthermore, Epsilon, Eta, and Theta Antliae were incorporated into the celestial temple, which also contained stars from modern Pyxis.[6]

Characteristics

[edit]

Covering 238.9 square degrees and hence 0.579% of the sky, Antlia ranks 62nd of the 88 modern constellations by area.[14] Its position in the Southern Celestial Hemisphere means that the whole constellation is visible to observers south of 49°N.[14][b] Hydra the sea snake runs along the length of its northern border, while Pyxis the compass, Vela the sails, and Centaurus the centaur line it to the west, south and east respectively. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union, is "Ant".[10] The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930,[c] are defined by a polygon with an east side, south side and ten other sides (facing the two other cardinal compass points) (illustrated in infobox at top-right). In the equatorial coordinate system, the right ascension coordinates of these borders lie between 09h 26.5m and 11h 05.6m , while the declination coordinates are between −24.54° and −40.42°.[2]

Features

[edit]
The constellation Antlia as seen by the naked eye

Stars

[edit]
See also: List of stars in Antlia

Lacaille gave nine stars Bayer designations, labelling them Alpha through to Theta, combining two stars next to each other as Zeta. Gould later added a tenth, Iota Antliae. Beta and Gamma Antliae (now HR 4339 and HD 90156) ended up in the neighbouring constellation Hydra once the constellation boundaries were delineated in 1930.[16] Within the constellation's borders, there are 42 stars brighter than or equal to apparent magnitude 6.5.[d][14] The constellation's two brightest stars—Alpha and Epsilon Antliae—shine with a reddish tinge.[18] Alpha is an orange giant of spectral type K4III that is a suspected variable star, ranging between apparent magnitudes 4.22 and 4.29.[19] It is located 320 ± 10 light-years away from Earth.[20] Estimated to be shining with around 480 to 555 times the luminosity of the Sun, it is most likely an ageing star that is brightening and on its way to becoming a Mira variable star, having converted all its core fuel into carbon.[21] Located 590 ± 30 light-years from Earth,[22] Epsilon Antliae is an evolved orange giant star of spectral type K3 IIIa, that has swollen to have a diameter about 69 times that of the Sun,[23] and a luminosity of around 1279 Suns.[24] It is slightly variable.[25] At the other end of Antlia, Iota Antliae is likewise an orange giant of spectral type K1 III.[26] It is 202 ± 2 light-years distant.[27]

Located near Alpha is Delta Antliae, a binary star, 450 ± 10 light-years distant from Earth.[28] The primary is a blue-white main sequence star of spectral type B9.5V and magnitude 5.6, and the secondary is a yellow-white main sequence star of spectral type F9Ve and magnitude 9.6.[29] Zeta Antliae is a wide optical double star. The brighter star—Zeta1 Antliae—is 410 ± 40 light-years distant and has a magnitude of 5.74,[30] though it is a true binary star system composed of two white main sequence stars of magnitudes 6.20 and 7.01 that are separated by 8.042 arcseconds.[31] The fainter star—Zeta2 Antliae—is 386 ± 5 light-years distant[32] and of magnitude 5.9.[33] Eta Antliae is another double composed of a yellow white star of spectral type F1V and magnitude 5.31, with a companion of magnitude 11.3.[31] Theta Antliae is likewise double, most likely composed of an A-type main sequence star and a yellow giant.[34] S Antliae is an eclipsing binary star system that varies in apparent magnitude from 6.27 to 6.83 over a period of 15.6 hours.[35] The system is classed as a W Ursae Majoris variable—the primary is hotter than the secondary and the drop in magnitude is caused by the latter passing in front of the former. Calculating the properties of the component stars from the orbital period indicates that the primary star has a mass 1.94 times and a diameter 2.026 times that of the Sun, and the secondary has a mass 0.76 times and a diameter 1.322 times that of the Sun.[36] The two stars have similar luminosity and spectral type as they have a common envelope and share stellar material.[37] The system is thought to be around 5–6 billion years old. The two stars will eventually merge to form a single fast-spinning star.[36]

T Antliae is a yellow-white supergiant of spectral type F6Iab and Classical Cepheid variable ranging between magnitude 8.88 and 9.82 over 5.9 days.[38] U Antliae is a red C-type carbon star and is an irregular variable that ranges between magnitudes 5.27 and 6.04.[39] At 910 ± 50 light-years distant,[40] it is around 5819 times as luminous as the Sun.[24] BF Antliae is a Delta Scuti variable that varies by 0.01 of a magnitude.[41] HR 4049, also known as AG Antliae, is an unusual hot variable ageing star of spectral type B9.5Ib-II. It is undergoing intense loss of mass[42] and is a unique variable that does not belong to any class of known variable star, ranging between magnitudes 5.29 and 5.83 with a period of 429 days.[43] It is around 6000 light-years away from Earth.[44] UX Antliae is an R Coronae Borealis variable with a baseline apparent magnitude of around 11.85, with irregular dimmings down to below magnitude 18.0.[45] A luminous and remote star, it is a supergiant with a spectrum resembling that of a yellow-white F-type star but it has almost no hydrogen.[46]

A composite image of NGC 2997

HD 93083 is an orange dwarf star of spectral type K3V that is smaller and cooler than the Sun. It has a planet that was discovered by the radial velocity method with the HARPS spectrograph in 2005. About as massive as Saturn, the planet orbits its star with a period of 143 days at a mean distance of 0.477 AU.[47] WASP-66 is a sunlike star of spectral type F4V. A planet with 2.3 times the mass of Jupiter orbits it every 4 days, discovered by the transit method in 2012.[48] DEN 1048-3956 is a brown dwarf of spectral type M8 located around 13 light-years distant from Earth. At magnitude 17 it is much too faint to be seen with the unaided eye. It has a surface temperature of about 2500 K. Two powerful flares lasting 4–5 minutes each were detected in 2002.[49] 2MASS 0939-2448 is a system of two cool and faint brown dwarfs, probably with effective temperatures of about 500 and 700 K and masses of about 25 and 40 times that of Jupiter, though it is also possible that both objects have temperatures of 600 K and 30 Jupiter masses.[50]

Deep-sky objects

[edit]
Galaxy ESO 376-16 is located nearly 23 million light-years from Earth.[51]

Antlia contains many faint galaxies,[52] the brightest of which is NGC 2997 at magnitude 10.6.[53] It is a loosely wound face-on spiral galaxy of type Sc. Though nondescript in most amateur telescopes, it presents bright clusters of young stars and many dark dust lanes in photographs.[33] Discovered in 1997, the Antlia Dwarf is a 14.8m dwarf spheroidal galaxy that belongs to the Local Group of galaxies.[54] In 2018 the discovery was announced of a very low surface brightness galaxy near Epsilon Antliae, Antlia 2, which is a satellite galaxy of the Milky Way.[55]

The Antlia Cluster, also known as Abell S0636, is a cluster of galaxies located in the Hydra–Centaurus Supercluster. It is the third nearest to the Local Group after the Virgo Cluster and the Fornax Cluster.[56] The cluster's distance from earth is 40.5 to 40.9 Mpc (132.1 to 133.4 Mly)[57] Located in the southeastern corner of the constellation, it boasts the giant elliptical galaxies NGC 3268 and NGC 3258 as the main members of a southern and northern subgroup respectively, and contains around 234 galaxies in total.[52]

Antlia is home to the huge Antlia Supernova Remnant, one of the largest supernova remnants in the sky.[58]

Notes

[edit]

References

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

Antlia

View on Grokipedia
from Grokipedia
Antlia is a faint southern constellation representing an air pump, a device symbolizing early experiments in vacuum physics, introduced by French astronomer Nicolas-Louis de Lacaille during his 1751–1752 expedition to the . Spanning 239 square degrees, Antlia ranks as the 62nd largest of modern constellations and lies south of the , making it best visible from the between late March and early June. Its position is bordered by Hydra to the north, Vela and to the east, and to the south and west, occupying a relatively sparse region of the sky with no ancient mythological associations. Originally named Antlia Pneumatica by Lacaille to honor the pneumatic machine invented by in the 1670s, the name was shortened to Antlia in 1841 by British astronomer Francis Baily for the British Association Catalogue. The constellation contains no stars brighter than fourth magnitude, rendering it challenging for naked-eye observation even under dark skies. Its brightest star, Alpha Antliae, is an orange giant of apparent magnitude 4.25 located approximately 366 light-years from , suspected to be a low-amplitude variable. The second-brightest, Epsilon Antliae, shines at magnitude 4.52 and is another aging orange about 700 light-years distant. Other notable stars include Theta Antliae, a with a blue-white main-sequence primary of magnitude 4.79 at 370 light-years, and Iota Antliae, an orange giant of magnitude 4.60. Antlia hosts several deep-sky objects of interest to astronomers. The Antlia Cluster (Abell S0636), a rich about 130 million light-years away, comprises over 200 galaxies dominated by the giant ellipticals NGC 3258 and NGC 3268, which are interacting and may indicate a recent merger of subclusters. Another highlight is NGC 2997, a face-on of 10.7 located 30 million light-years distant, known for its prominent dust lanes and active nucleus. The constellation also contains the Antlia Dwarf, a dwarf in the Local Group discovered in 1997, featuring stars at various evolutionary stages, and Antlia 2, another faint identified in 2018 as one of the Milky Way's most underluminous satellites.

History

Origin in Western Astronomy

The constellation Antlia originated from the observations of French astronomer Nicolas-Louis de Lacaille during his expedition to the from 1751 to 1752, where he conducted a systematic survey of the southern sky and cataloged nearly 10,000 stars. To organize the uncataloged regions, Lacaille introduced 14 new constellations, including Antlia, filling gaps between existing Ptolemaic figures and reflecting the scientific advancements of the Enlightenment era. Lacaille named the constellation La Machine Pneumatique on his 1756 star map, Latinized to Antlia Pneumatica (the Air Pump) in his posthumously published 1763 atlas Coelum Australe Stelliferum, honoring the single-cylinder invented by German physicist in the 1670s as a symbol of . This choice underscored the period's fascination with mechanical instruments and empirical science, with Papin's device famously used in vacuum experiments detailed in his 1674 work Nouvelles expériences du vide. The name was later simplified to Antlia in 1845 by British astronomer Francis Baily, following a suggestion from , to align with the concise nomenclature of ancient constellations. Lacaille initially defined Antlia's boundaries using faint stars previously unassigned to major figures, encompassing a sparse region near the stern of the ancient ship . These delineations appeared in his 1763 atlas, providing the first formal outline for the constellation. Antlia received official recognition as one of the 88 modern constellations at the International Astronomical Union's inaugural in 1922, with boundaries later precisely delimited by Belgian Eugène Delporte in 1930 using and coordinates.

Visibility in Non-Western Cultures

In non-Western astronomical traditions, the faint stars of Antlia did not form a unified constellation figure, largely due to their low magnitudes—none brighter than fourth magnitude—and their position low on the southern horizon, rendering them invisible from most northern latitudes in pre-telescopic eras. This obscurity limited their prominence in cultural sky lore beyond the , where observations focused on brighter navigational or seasonal markers rather than dim, scattered patterns. Chinese astronomers, observing from latitudes that allowed visibility of the southern sky, integrated Antlia's stars into several minor asterisms within their traditional system of the and outer enclosures. Stars in the southern portion of modern Antlia, including Iota Antliae, were assigned to Dong'ou, an asterism symbolizing a historical region in southern associated with non-Han peoples or "barbarians" in ancient texts. , , and Antliae formed part of Tianmiao, the Celestial Temple, a larger grouping that extended into neighboring and represented imperial or divine structures in the quadrant of the southern sky. These assignments appear in historical Chinese star catalogs, such as those from the onward, but lacked narrative myths tied specifically to the air pump concept later adopted in the West. The absence of a cohesive Antlia-like figure underscores how pre-modern cultures prioritized functional or symbolic groupings over faint, unstructured patterns.

Characteristics

Position and Visibility

Antlia is positioned entirely in the , spanning a range of 09h 27m to 11h 06m and a range of −25° to −40°. This places it adjacent to the constellations Hydra to the north, to the northeast, Vela to the southeast, and to the southwest. The constellation's visibility is optimized for observers in the during late to June, when it culminates in the evening sky amid the season of southern autumn, providing the most favorable conditions for observation after sunset. It can be seen from latitudes between +45° and −90°, with the entire constellation visible south of 45°N. For latitudes south of 50°S, parts of Antlia appear circumpolar, remaining above the horizon throughout the night, though the whole constellation is circumpolar only from higher southern latitudes. Conversely, it never rises above the horizon for observers north of 45°N, rendering it inaccessible from most northern temperate regions. Antlia's faint stellar composition exacerbates viewing difficulties in areas impacted by pollution, as its lack of prominent bright stars demands for effective observation, often requiring or telescopes even under ideal conditions.

Size and Boundaries

Antlia is one of the 88 modern constellations officially recognized by the (IAU). It spans an area of 239 square degrees, ranking 62nd in among these constellations and covering approximately 0.58% of the . The boundaries of Antlia form an irregular , defined by a consisting of an east side, a south side, and ten intermediate segments along lines of and . These boundaries connect key stars such as Alpha Antliae and extend to shared endpoints with adjacent constellations, including Hydra to the north and Vela to the southeast. The IAU's delineation ensures that every point on the belongs to exactly one constellation. Nicolas-Louis de Lacaille introduced Antlia during his 1751–1752 expedition to the , originally depicting it as a compact outline resembling an air pump (la Machine Pneumatique) without formal borders; the constellation catalog was published in 1763. In 1930, Belgian astronomer Eugène Delporte standardized the boundaries for all constellations under IAU auspices, adjusting Lacaille's informal figure to a precise polygonal region; this revision reassigned stars like Beta and Gamma Antliae to the neighboring constellation Hydra. Among other small southern constellations created by Lacaille, such as —which covers 221 square degrees and ranks 65th—Antlia occupies a modestly larger area.

Stellar Features

Principal Stars

The principal stars of Antlia bear Bayer designations assigned by French Nicolas Louis de Lacaille in his 1751–1752 southern sky catalog, later published in 1756, where he labeled nine stars from Alpha to Iota Antliae to outline the faint constellation representing an air pump. In 1879, American Benjamin Gould refined the constellation boundaries for his Uranometria Argentina, reassigning Beta and Gamma Antliae to the neighboring constellation Hydra while retaining the other designations within Antlia's current IAU-defined limits. Alpha Antliae serves as the brightest and namesake star of the constellation, exhibiting an apparent visual magnitude of 4.25 that renders it faintly visible to the from dark sites. Classified as an orange giant of spectral type K4 III, it lies approximately 366 light-years distant, with a surface around 4,070 , a radius 41 times the Sun's, and 412 times solar, indicating an evolved star likely on the . Beta Antliae, Lacaille's second-designated star but now positioned in Hydra due to boundary adjustments, is a white main-sequence star of spectral type A1 V with an apparent magnitude of 5.79. It resides about 366 light-years away and displays a proper motion of +18.45 mas/year in right ascension and -29.97 mas/year in declination, reflecting its galactic orbit. Gamma Antliae, similarly reassigned to Hydra, is a yellow main-sequence star of spectral type G5 V shining at magnitude 6.92 from a distance of 72 light-years. Observations suggest it may form a wide binary system, though confirmation requires further astrometric data. Epsilon Antliae is the second-brightest in Antlia, an orange giant of spectral type K3 III with an of 4.51 located approximately 710 light-years away. It is an evolved with a around 500 times that of the Sun. Among the remaining Bayer-designated within Antlia's modern boundaries, Zeta Antliae is an optical system; the brighter component, Zeta¹ Antliae, is itself a binary pair of A-type separated by 8.1 arcseconds at a position angle of 212°, with a combined magnitude of 5.74, located ~340 light-years away. Zeta² Antliae, magnitude 5.5, is a white ~370 light-years distant. Eta Antliae stands out as a system with a combined of 5.23; its primary component is a yellow-white F1 V main-sequence star at 108 light-years distant, while the fainter companion contributes to its visual binary nature separable by small telescopes. Delta Antliae, fainter at magnitude 5.59, is another binary, consisting of a hot B9.5 V primary and an F9 V secondary separated by about 2,200 AU, located 481 light-years away. Theta Antliae is a blue-white main-sequence star of spectral type B8 V with magnitude 5.30 at ~386 light-years. Iota Antliae is an orange giant of spectral type K1 III shining at magnitude 4.60 from 208 light-years, and it is a spectroscopic .
StarBayer DesignationApparent MagnitudeSpectral TypeDistance (light-years)Key Notes
Alpha Antliae4.25K4 III (orange giant)366Brightest in constellation; evolved giant with high .
Beta Antliae5.79A1 V (white main-sequence)366Historical designation; now in Hydra; notable .
Gamma Antliae6.92G5 V (yellow main-sequence)72Historical designation; now in Hydra; possible binary.
Epsilon Antliae4.51K3 III (orange giant)710Second-brightest; evolved subgiant.
Zeta Antliae5.4 (combined)A-type (Zeta¹ binary; optical double)340 (Zeta¹); 370 (Zeta²)Optical double; Zeta¹ is visual binary.
Eta Antliae5.23F1 V (primary; )108Visual binary; primary is main-sequence yellow-white dwarf.
Delta Antliae5.59B9.5 V + F9 V (binary)481Wide binary; primary is hot blue-white main-sequence star.
Theta Antliae5.30B8 V (blue-white main-sequence)386Main-sequence star.
Iota Antliae4.60K1 III (orange giant; spectroscopic binary)208Third-brightest; .

Variable and Multiple Stars

Antlia hosts a variety of variable stars, including long-period variables and eclipsing binaries, as well as a significant population of RR Lyrae stars associated with the Antlia 2 in the constellation's direction. These objects provide insights into , binary dynamics, and galactic structure. Recent surveys, such as those utilizing data from the mission, have refined classifications and proper motions for many of these systems, enabling better characterization of their variability types and orbital behaviors. Prominent among the long-period variables is V Antliae, a Mira-type exhibiting pulsations with a period of 301.55 days and a visual magnitude range from 8.83 to 13.20. This variability arises from radial pulsations in the 's extended atmosphere, typical of stars undergoing mass loss. Similarly, U Antliae is classified as a long-period variable with a pulsation period of approximately 349.53 days; as a carbon-rich , it displays irregular fluctuations in brightness around a mean G-band magnitude of 4.19, linked to its advanced evolutionary stage and episodic mass ejection events. Eclipsing and ellipsoidal binaries in Antlia offer opportunities to study close stellar interactions. S Antliae is a spectroscopic binary and ellipsoidal variable with an of 0.648346 days, where tidal distortions cause brightness variations; its visual magnitude centers around 6.45, and analyses have been used to derive component masses and evolutionary states. Such systems, often contact binaries of the W Ursae Majoris type, highlight processes in low-mass stars. A notable concentration of short-period variables appears in the Antlia 2 , located approximately 124 kpc from the . Surveys have identified 318 RR Lyrae stars there, with fundamental-mode RRab stars having a mean period of 0.599 days and first-overtone RRc stars averaging 0.368 days; this places Antlia 2 in the Oosterhoff-intermediate category, suggesting an intermediate population. These stars serve as standard candles for distance calibration and reveal tidal stripping effects, with a of 13 km s⁻¹ kpc⁻¹ indicating dynamical disruption by the . Eight anomalous Cepheids were also detected, providing further constraints on the galaxy's history. Multiple star systems in Antlia include visual binaries resolvable with moderate telescopes. Delta Antliae is a wide binary comprising a B9.5 V main-sequence primary and an F9 V secondary, with an of 5.59 and a separation of about 11 arcseconds (corresponding to roughly 2200 AU at its distance of ~481 light-years); no full orbital parameters are established, but it exemplifies hierarchical systems common in the field. Zeta Antliae forms an optical double, with its brighter component (Zeta¹ Antliae) itself a close binary pair of A-type separated by 8.1 arcseconds at position angle 212°, located ~340 light-years away. These configurations aid in understanding companion influences on .

Deep-Sky Objects

Galaxies

Antlia hosts several notable extragalactic structures, including individual galaxies and a distant cluster, observable primarily from southern latitudes due to the constellation's position. These objects provide insights into galaxy evolution, active galactic nuclei, and cluster dynamics, with distances ranging from nearby members to remote clusters over 100 million light-years away. One prominent feature is NGC 2997, a nearly face-on classified as SAB(rs)c, located approximately 37 million light-years (11.3 Mpc) distant. The Antlia Galaxy Cluster, also known as Abell S0636, is a poor cluster situated about 130 million light-years (40 Mpc) away, containing over 200 member galaxies and serving as a key example of an evolving cluster environment. Centered near the NGC 3268, which dominates the core alongside the nearby elliptical NGC 3258, the cluster features a mix of early-type galaxies. NGC 3271, a barred , stands out as one of the brighter members, contributing to the cluster's total . Observations indicate dynamical substructures, with radial velocities spanning 1000 to 4000 km/s, suggesting recent accretion events. Antlia also contains the Antlia Dwarf Galaxy, a low-surface-brightness dwarf spheroidal discovered in 1997 and residing in the Local Group at about 4.2 million light-years (1.3 Mpc). As a likely satellite of the NGC 3109, it shows evidence of tidal interactions, with an elongated structure and stellar populations indicating multiple episodes of . Its of around -9.7 highlights its faintness, making it a valuable probe of and hierarchical galaxy formation. No Messier catalog objects lie within Antlia's boundaries, emphasizing the constellation's focus on deeper-sky targets. Antlia 2, an ultra-faint dwarf satellite galaxy of the Milky Way discovered in 2018 through analysis of Gaia Data Release 2 proper motions and photometry, is located approximately 130 kpc from the Sun behind the Galactic disk at a latitude of about 11°. Antlia 2 spans 1.26° on the sky, equivalent to a physical diameter of roughly 2.9 kpc, yet it exhibits an extraordinarily low surface brightness of around 32 mag arcsec⁻² in V-band, rendering it nearly invisible in traditional surveys. Its stellar population consists predominantly of ancient, metal-poor red giants with an average metallicity of [Fe/H] ≈ -1.5, indicating formation over 10 billion years ago, and no evidence of recent star formation, consistent with tidal disruption by the Milky Way's gravitational field. This structure's large size relative to its total luminosity (M_V ≈ -9) challenges models of dwarf galaxy evolution, suggesting significant mass loss and a cored dark matter profile potentially shaped by tidal interactions, with dynamical mass estimates implying a dark matter fraction exceeding 99%. Infrared observations of Antlia 2 using facilities like Spitzer have been limited due to its faintness, but they reveal cool, evolved stars dominating the population, with no embedded young stellar objects or active star-forming regions. Variable stars within Antlia 2, including RR Lyrae types, provide kinematic insights into their dynamics.

Star Clusters and Nebulae

Antlia contains few prominent star clusters or nebulae, making it one of the more barren southern constellations in terms of intra-galactic aggregates and gaseous structures. Unlike neighboring regions rich in features, such as Vela, Antlia lacks bright open clusters, globular clusters, or notable emission and reflection nebulae, with deep-sky interest primarily centered on distant galaxies. No major open clusters are cataloged within Antlia's boundaries, though loose OB associations akin to those in nearby constellations may contribute to sparse stellar groupings near brighter stars like Beta Antliae.

References

  1. https://noirlab.edu/public/education/constellations/antlia/
  2. http://www.ianridpath.com/startales/antlia.html
  3. https://theskylive.com/sky/constellations/antlia-constellation
  4. https://www.gemini.edu/news/press-releases/noirlab2501
  5. https://www.space.com/the-universe/galaxies/dark-energy-camera-captures-thousands-of-galaxies-in-stunning-image
  6. https://esahubble.org/images/potw1209a/
  7. https://www.space.com/19919-southern-night-sky-constellations-lacaille.html
  8. http://assa.saao.ac.za/sections/deep-sky/lacailles-catalogue/
  9. http://pbarbier.com/lacaille/lacaille.html
  10. https://mathshistory.st-andrews.ac.uk/Biographies/Papin/
  11. https://www.constellation-guide.com/constellation-list/antlia-constellation/
  12. https://theplanets.org/constellations/antlia-constellation/
  13. https://www.britannica.com/topic/Antlia
  14. https://astropixels.com/constellations/charts/Ant.html
  15. https://www.iau.org/public/themes/constellations/
  16. https://www.constellation-guide.com/constellation-list/pyxis-constellation/
  17. http://stars.astro.illinois.edu/sow/alphaant.html
  18. https://theskylive.com/sky/stars/epsilon-antliae-star
  19. https://theskylive.com/sky/stars/theta-antliae-star
  20. https://theskylive.com/sky/stars/iota-antliae-star
  21. https://www.aanda.org/articles/aa/full_html/2023/06/aa45591-22/aa45591-22.html
  22. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V+Antliae
  23. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=U+Antliae
  24. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=S+Antliae
  25. https://adsabs.harvard.edu/full/1956ApJ...124..208P
  26. https://arxiv.org/abs/2112.08467
  27. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=Delta+Antliae
  28. https://www.universetoday.com/articles/antila
  29. https://arxiv.org/abs/1807.02043
  30. https://academic.oup.com/mnras/article/416/1/522/1213827
  31. https://noirlab.edu/public/images/noirlab2501a/
  32. https://arxiv.org/abs/1510.04274
  33. https://arxiv.org/abs/astro-ph/9706197
  34. https://arxiv.org/abs/1109.1142
  35. https://arxiv.org/abs/1811.04082
  36. https://iopscience.iop.org/article/10.3847/1538-4357/ac43bd
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