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Gamma Piscis Austrini

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Gamma Piscis Austrini
Location of γ Piscis Austrini (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Piscis Austrinus
Right ascension 22h 52m 31.5351s[1]
Declination −32° 52′ 31.806″[1]
Apparent magnitude (V) +4.448[2] (4.59 + 8.20)[3]
Characteristics
γ PsA A
Spectral type A0 Vp(SrCrEu)[4]
U−B color index −0.038[2]
B−V color index −0.046[2]
γ PsA B
Spectral type F5 V[5]
U−B color index −0.08[5]
B−V color index +0.44[5]
Astrometry
Radial velocity (Rv)16.5±2.7[6] km/s
Proper motion (μ) RA: −32.73 mas/yr[1]
Dec.: −21.21 mas/yr[1]
Parallax (π)15.14 ± 0.57 mas[1]
Distance215 ± 8 ly
(66 ± 2 pc)
Absolute magnitude (MV)−0.20/3.50[5]
Orbit[7]
PrimaryAa
CompanionAb
Period (P)15 yr
Semi-major axis (a)143.5 mas
(9.2 AU)
Details[7]
Aa
Mass2.65 M☉
Radius2.9 R☉
Surface gravity (log g)3.92[8] cgs
Temperature9,950 K
Rotation2.542±0.001 d
Rotational velocity (v sin i)47[8] km/s
Age350 Myr
Ab
Mass0.94 M☉
Radius0.84 R☉
Temperature5,500 K
B
Mass1.20 M☉
Radius1.15 R☉
Temperature6,400 K
Other designations
γ PsA, 22 Piscis Austrini, CD−33° 16270, HD 216336, HIP 112948, HR 8695, SAO 214153, WDS J22525-3253AB[9]
Database references
SIMBADγ PsA
γ PsA A
γ PsA B

Gamma Piscis Austrini, Latinized from γ Piscis Austrini, is trile star system[7] in the southern constellation of Piscis Austrinus. It is visible to the naked eye with a combined apparent visual magnitude of +4.448.[2] Based upon an annual parallax shift of 15.1 mas as seen from the Earth,[1] the system is located about 216 light years from the Sun.

The A and B components, as of 2010, are separated by 4 arc seconds in the sky along a position angle of 255°.[10] The "A" component is itself a binary, made up of two stars orbiting each other with an orbital period of 15 years and a separation of nine astronomical units,[7] with a combined apparent magnitude of 4.59.[3] The component Aa has 2.65 times more mass than the Sun and 2.9 times its radius, being a chemically peculiar star[7] with a spectral type A0 Vp(SrCrEu).[4] The Ab component is smaller, at 0.94 times the Sun's mass and 0.84 times its radius.[7] The fainter magnitude 8.20[3] companion, component B, is an F-type main sequence star with a class of F5 V.[5] It has 20% more mass than the Sun and a radius 15% larger.[7]

Gamma Piscis Austrini is moving through the Galaxy at a speed of 24.1 km/s relative to the Sun. Its projected Galactic orbit carries it between 21,605 and 30,903 light-years from the center of the Galaxy. It came closest to the Sun 1.8 million years ago at a distance of 157 light-years.[11]

The current age of the system is 350 million years. It will become a triple white dwarf system within 14 billion years.[7]

Naming

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In Chinese, 敗臼 (Bài Jiù), meaning Decayed Mortar, refers to an asterism consisting of refers to an asterism consisting of γ Piscis Austrini, γ Gruis, λ Gruis and 19 Piscis Austrini. Consequently, the Chinese name for γ Piscis Austrini itself is 敗臼三 (Bài Jiù sān, English: the Third Star of Decayed Mortar.)[12]

References

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  1. ^ a b c d e van Leeuwen, F. (2007-11-01). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. ISSN 0004-6361.
  2. ^ a b c d Rakos, K. D.; et al. (February 1982), "Photometric and astrometric observations of close visual binaries", Astronomy and Astrophysics Supplement Series, 47: 221–235, Bibcode:1982A&AS...47..221R.
  3. ^ a b c Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  4. ^ a b Abt, Helmut A.; Morrell, Nidia I. (July 1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", Astrophysical Journal Supplement, 99: 135, Bibcode:1995ApJS...99..135A, doi:10.1086/192182.
  5. ^ a b c d e Corbally, C. J. (1984), "Close visual binaries. I - MK classifications", Astrophysical Journal Supplement Series, 55: 657, Bibcode:1984ApJS...55..657C, doi:10.1086/190973.
  6. ^ Gontcharov, G. A. (2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  7. ^ a b c d e f g h Waisberg, Idel; Klein, Ygal; Katz, Boaz (2024-10-01). "Hidden Companions to Intermediate-mass Stars. Upgraded Multiplicity 2 → 3. XXIII. Discovery of a 0.94M ⊙, 9.2 au Companion to the Ap Star Gamma Piscis Austrini A". Research Notes of the American Astronomical Society. 8 (10): 258. Bibcode:2024RNAAS...8..258W. doi:10.3847/2515-5172/ad84fb. ISSN 2515-5172.
  8. ^ a b David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  9. ^ "gam PsA -- Double or multiple star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-05-18.
  10. ^ Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
  11. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  12. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 5 日 Archived 2011-05-21 at the Wayback Machine
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