Eta Piscis Austrini

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Eta Piscis Austrini
Diagram showing star positions and boundaries of the Piscis Austrinus constellation and its surroundings
Cercle rouge 100%.svg
Location of η Piscis Austrini (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Piscis Austrinus
Right ascension 22h 00m 50.22537s[1]
Declination −28° 27′ 13.4639″[1]
Apparent magnitude (V) +5.43[2] (5.742 + 6.825)[3]
Spectral type B8 V[4] or B7 IVe[5]
U−B color index −0.30[2]
B−V color index −0.10[2]
Proper motion (μ) RA: +15.57[1] mas/yr
Dec.: −1.03[1] mas/yr
Parallax (π)3.99 ± 0.48[1] mas
Distanceapprox. 820 ly
(approx. 250 pc)
Absolute magnitude (MV)−1.53[5]
η PsA A
Mass4.01±0.18[4] M
Luminosity604[4] L
Surface gravity (log g)3.84[6] cgs
Temperature11,272[4] K
Rotational velocity (v sin i)265[4] km/s
Age115[6] Myr
Other designations
η PsA, 12 Piscis Austrini, CPD−29° 6659, HD 209014, HIP 108661, HR 8386, SAO 190822, WDS J22008-2827AB[7]
Database references

Eta Piscis Austrini (η Piscis Austrini) is binary star[3] 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,[2] 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,[1] the system is located roughly 820 light years from the Sun.

The magnitude 5.7 primary, component A,[3] is a blue-white hued Be star[6] with a stellar classification B8 V.[4] At the age of 115,[6] the star is spinning rapidly with a projected rotational velocity of 265.[4] 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.[4] The secondary, component B, has a visual magnitude of 6.8.[3]

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.[8][unreliable source?]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d 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. 
  3. ^ a b c d 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. 
  4. ^ a b c d e f g h Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052Freely accessible, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691. 
  5. ^ a b Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971Freely accessible, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. 
  6. ^ a b c d 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/0509119Freely accessible, Bibcode:2005A&A...441..235Z, doi:10.1051/0004-6361:20053051. 
  7. ^ "eta PsA -- Be Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-05-18. 
  8. ^ Eta Piscis Austrini (HIP 108661)