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Eta Piscis Austrini

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Eta Piscis Austrini (η Piscis Austrini) is binary star[2] system in the southern constellation of Piscis Austrinus. As of 2000, the two components had an angular separation of 1.818 arc seconds along a position angle of 113.4°. The pair have a combined apparent visual magnitude of +5.43,[5] which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 3.99 mas as seen from the Earth,[13] the system is located roughly 820 light years from the Sun.

η Piscis Austrini
Location of η Piscis Austrini (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Piscis Austrinus
A
Right ascension 22h 00m 50.22454s[1]
Declination −28° 27′ 13.4587″[1]
Apparent magnitude (V) 5.742[2]
B
Right ascension 22h 00m 50.34936s[3]
Declination −28° 27′ 14.1460″[3]
Apparent magnitude (V) 6.825[2]
Characteristics
Spectral type B6 III shell + B8.5 V[4]
U−B color index −0.30[5]
B−V color index −0.10[5]
Variable type suspected[6]
Astrometry
Absolute magnitude (MV)−1.53[7]
A
Proper motion (μ) RA: +15.289[1] mas/yr
Dec.: −0.096[1] mas/yr
Parallax (π)3.8087 ± 0.0932 mas[1]
Distance860 ± 20 ly
(263 ± 6 pc)
B
Proper motion (μ) RA: +17.554[3] mas/yr
Dec.: −1.229[3] mas/yr
Parallax (π)4.5342 ± 0.3306 mas[3]
Distance720 ± 50 ly
(220 ± 20 pc)
Details
η PsA A
Mass4.01±0.18[8] M☉
Luminosity881[9] L☉
Surface gravity (log g)3.48[9] cgs
Temperature12,310[9] K
Rotational velocity (v sin i)320[9] km/s
Age115[10] Myr
η PsA B
Mass3.6[11] M☉
Surface gravity (log g)4.17[11] cgs
Temperature14,144[11] K
Metallicity [Fe/H]−0.21[11] dex
Other designations
η PsA, 12 Piscis Austrini, CPD−29° 6659, HD 209014, HIP 108661, HR 8386, SAO 190822, WDS J22008-2827AB[12]
Database references
SIMBADdata

Although not catalogued formally as a variable star, brightness changes between magnitude 5,33 and 5.44 have been widely reported.[6][14] The type of variability is thought to be related to its rapid rotation and a surrounding shell, and is tentatively given as a combination of a Be star and Maia variable.[15]

The magnitude 5.7 primary, component A,[2] is a blue-white hued Be star[10] with a stellar classification B6 III.[4] At 115 million years old,[10] the star is spinning rapidly with a projected rotational velocity of 265.[8] It has an estimated four times the mass of the Sun and is radiating 604 times the solar luminosity at an effective temperature of 11,272 K.[8] The secondary, component B, has a visual magnitude of 6.8[2] and a spectral class of B8.5 V.[4]

Eta Piscis Austrini is moving through the Galaxy at a speed of 11.3 km/s relative to the Sun. Its projected Galactic orbit carries it between 23,600 and 30,800 light years from the center of the Galaxy.[16][unreliable source?]

References edit

  1. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b c d e Fabricius, C.; Makarov, V. V. (April 2000), "Two-colour photometry for 9473 components of close Hipparcos double and multiple stars", Astronomy and Astrophysics, 356: 141–145, Bibcode:2000A&A...356..141F.
  3. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  4. ^ a b c Corbally, C. J. (August 1984), "Close visual binaries. I - MK classifications", The Astrophysical Journal Supplement Series, 55: 657, Bibcode:1984ApJS...55..657C, doi:10.1086/190973, eISSN 1538-4365, ISSN 0067-0049.
  5. ^ a b c Feinstein, A.; Marraco, H. G. (November 1979), "The photometric behavior of Be Stars", Astronomical Journal, 84: 1713–1725, Bibcode:1979AJ.....84.1713F, doi:10.1086/112600.
  6. ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009), "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)", VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S, 1: B/gcvs, Bibcode:2009yCat....102025S.
  7. ^ 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.
  8. ^ a b c Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
  9. ^ a b c d Zorec, J.; Frémat, Y.; Domiciano De Souza, A.; Royer, F.; Cidale, L.; Hubert, A.-M.; Semaan, T.; Martayan, C.; Cochetti, Y. R.; Arias, M. L.; Aidelman, Y.; Stee, P. (2017), "Critical study of the distribution of rotational velocities of Be stars", Astronomy & Astrophysics, 595: A132, arXiv:1702.07684, Bibcode:2016A&A...595A.132Z, doi:10.1051/0004-6361/201628760.
  10. ^ a b c Zorec, J.; et al. (October 2005), "On the evolutionary status of Be stars. I. Field Be stars near the Sun", Astronomy and Astrophysics, 441 (1): 235–248, arXiv:astro-ph/0509119, Bibcode:2005A&A...441..235Z, doi:10.1051/0004-6361:20053051, S2CID 17592657.
  11. ^ a b c d Anders, F.; Khalatyan, A.; Queiroz, A. B. A.; Chiappini, C.; Ardevol, J.; Casamiquela, L.; Figueras, F.; Jimenez-Arranz, O.; Jordi, C.; Monguio, M.; Romero-Gomez, M.; Altamirano, D.; Antoja, T.; Assaad, R.; Cantat-Gaudin, T.; Castro-Ginard, A.; Enke, H.; Girardi, L.; Guiglion, G.; Khan, S.; Luri, X.; Miglio, A.; Minchev, I.; Ramos, P.; Santiago, B. X.; Steinmetz, M. (2022), "VizieR Online Data Catalog: StarHorse2, Gaia EDR3 photo-astrometric distances (Anders+, 2022)", Vizier Online Data Catalog, Bibcode:2022yCat.1354....0A.
  12. ^ "eta PsA -- Be Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-05-18.
  13. ^ van Leeuwen, F. (2007), "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, S2CID 18759600.
  14. ^ "NSV 13993", International Variable Star Index, AAVSO, retrieved 2023-04-02
  15. ^ Balona, L. A.; Handler, G.; Chowdhury, S.; Ozuyar, D.; Engelbrecht, C. A.; Mirouh, G. M.; Wade, G. A.; David-Uraz, A.; Cantiello, M. (2019), "Rotational modulation in TESS B stars", Monthly Notices of the Royal Astronomical Society, 485 (3): 3457, arXiv:1902.09470, Bibcode:2019MNRAS.485.3457B, doi:10.1093/mnras/stz586.
  16. ^ Eta Piscis Austrini (HIP 108661)[permanent dead link]
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