Location of η Piscis Austrini (circled) | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Piscis Austrinus |
| A | |
| Right ascension | 22 00 50.22454 |
| Declination | −28° 27′ 13.4587″ |
| Apparent magnitude (V) | 5.742 |
| B | |
| Right ascension | 22 00 50.34936 |
| Declination | −28° 27′ 14.1460″ |
| Apparent magnitude (V) | 6.825 |
| Characteristics | |
| Spectral type | B6 III shell + B8.5 V |
| U−B color index | −0.30 |
| B−V color index | −0.10 |
| Variable type | suspected |
| Astrometry | |
| Absolute magnitude (MV) | −1.53 |
| A | |
| Proper motion (μ) | RA: +15.289 mas/yr Dec.: −0.096 mas/yr |
| Parallax (π) | 3.8087 ± 0.0932 mas |
| Distance | 860 ± 20 ly (263 ± 6 pc) |
| B | |
| Proper motion (μ) | RA: +17.554 mas/yr Dec.: −1.229 mas/yr |
| Parallax (π) | 4.5342 ± 0.3306 mas |
| Distance | 720 ± 50 ly (220 ± 20 pc) |
| Details | |
| η PsA A | |
| Mass | 4.01±0.18 M☉ |
| Luminosity | 881 L☉ |
| Surface gravity (log g) | 3.48 cgs |
| Temperature | 12,310 K |
| Rotational velocity (v sin i) | 320 km/s |
| Age | 115 Myr |
| η PsA B | |
| Mass | 3.6 M☉ |
| Surface gravity (log g) | 4.17 cgs |
| Temperature | 14,144 K |
| Metallicity | −0.21 dex |
| Other designations | |
| η PsA, 12 Piscis Austrini, CPD−29° 6659, HD 209014, HIP 108661, HR 8386, SAO 190822, WDS J22008-2827AB | |
| Database references | |
| SIMBAD | data |
Eta Piscis Austrini (η Piscis Austrini) is binary star 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, 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, the system is located roughly 820 light years from the Sun.
Although not catalogued formally as a variable star, brightness changes between magnitude 5,33 and 5.44 have been widely reported. 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.
The magnitude 5.7 primary, component A, is a blue-white hued Be star with a stellar classification B6 III. At 115 million years old, the star is spinning rapidly with a projected rotational velocity of 265. 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. The secondary, component B, has a visual magnitude of 6.8 and a spectral class of B8.5 V.
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.
References
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
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- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
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- Eta Piscis Austrini (HIP 108661)
