Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Piscis Austrinus |
Right ascension | 22h 40m 39.34075s[1] |
Declination | −27° 02′ 37.0157″[1] |
Apparent magnitude (V) | +4.17[2] |
Characteristics | |
Spectral type | B8 Ve[3] or B8 IVe[4] |
U−B color index | −0.31[2] |
B−V color index | −0.11[2] |
Astrometry | |
Radial velocity (Rv) | +1.1±2.8[5] km/s |
Proper motion (μ) | RA: +23.22[1] mas/yr Dec.: −0.16[1] mas/yr |
Parallax (π) | 8.0981 ± 0.3582 mas[6] |
Distance | 400 ± 20 ly (123 ± 5 pc) |
Absolute magnitude (MV) | −1.66[4] |
Details | |
Mass | 4.10±0.19[7] M☉ |
Radius | 3.2[8] R☉ |
Luminosity | 661[7] L☉ |
Surface gravity (log g) | 3.93[9] cgs |
Temperature | 11,066[7] K |
Rotational velocity (v sin i) | 216[7] km/s |
Other designations | |
Database references | |
SIMBAD | data |
Epsilon Piscis Austrini, Latinized from ε Piscis Austrini, is a blue-white hued star in the southern constellation of Piscis Austrinus. It is visible to the naked eye with an apparent visual magnitude of +4.17.[2] Based upon an annual parallax shift of 8.0981 ± 0.3582 mas as seen from the GAIA satellite, the system is located roughly 400 light years from the Sun.[6]
This is a B-type main sequence star with a stellar classification of B8 Ve.[3] It is a Be star that is spinning rapidly with a projected rotational velocity of 216 km/s,[7] compared to an equatorial critical velocity of 301 km/s.[9] The star has 4.1 times the mass of the Sun and is radiating 661 times the solar luminosity from its photosphere at an effective temperature of 11,066 K.[7]
Epsilon Piscis Austrini is moving through the Galaxy at a speed of 18.7 km/s relative to the Sun. Its projected Galactic orbit carries it between 23,917 and 28,138 light-years from the center of the Galaxy.[11]
Naming
[edit]In Chinese, 羽林軍 (Yǔ Lín Jūn), meaning Palace Guard, refers to an asterism consisting of:
- ε Piscis Austrini
- 29 Aquarii
- 35 Aquarii
- 41 Aquarii
- 47 Aquarii
- 49 Aquarii
- λ Piscis Austrini
- HD 212448
- 21 Piscis Austrini
- 20 Piscis Austrini
- υ Aquarii
- 68 Aquarii
- 66 Aquarii
- 61 Aquarii
- 53 Aquarii
- 50 Aquarii
- 56 Aquarii
- 45 Aquarii
- 58 Aquarii
- 64 Aquarii
- 65 Aquarii
- 70 Aquarii
- 74 Aquarii
- τ2 Aquarii
- τ1 Aquarii
- δ Aquarii
- 77 Aquarii
- 88 Aquarii
- 89 Aquarii
- 86 Aquarii
- 101 Aquarii
- 100 Aquarii
- 99 Aquarii
- 98 Aquarii
- 97 Aquarii
- 94 Aquarii
- ψ3Aquarii
- ψ2Aquarii
- ψ1Aquarii
- 87 Aquarii
- 85 Aquarii
- 83 Aquarii
- χ Aquarii
- ω1 Aquarii
- ω2 Aquarii
Consequently, the Chinese name for ε Piscis Austrini itself is 羽林軍八 (Yǔ Lín Jūn bā, English: the Eighth Sixth Star of Palace Guard.)[12]
References
[edit]- ^ a b c d 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.
- ^ 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.
- ^ a b Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal, 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590.
- ^ a b 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.
- ^ Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 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.
- ^ a b Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ a b c d e f Zorec, J.; Royer, F. (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.
- ^ Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics, 367 (3rd ed.): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
- ^ a b Chauville, J.; et al. (November 2001), "High and intermediate-resolution spectroscopy of Be stars 4481 lines", Astronomy and Astrophysics, 378: 8618–82, Bibcode:2001A&A...378..861C, doi:10.1051/0004-6361:20011202, hdl:11336/36962.
- ^ "eps PsA -- Be Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-05-18.
- ^ 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.
- ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 7 日 Archived 2011-05-21 at the Wayback Machine