Astronomy:Omicron Hydrae
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Short description: Blue-hued star in the constellation Hydra
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Hydra[1] |
| Right ascension | 11h 40m 12.78970s[2] |
| Declination | −34° 44′ 40.7733″[2] |
| Apparent magnitude (V) | 4.70[3] |
| Characteristics | |
| Spectral type | B9 V[4] |
| U−B color index | −0.20[3] |
| B−V color index | −0.08[3] |
| Astrometry | |
| Radial velocity (Rv) | +5.9[5] km/s |
| Proper motion (μ) | RA: −43.24[2] mas/yr Dec.: −1.61[2] mas/yr |
| Parallax (π) | 7.27 ± 0.16[2] mas |
| Distance | 449 ± 10 ly (138 ± 3 pc) |
| Absolute magnitude (MV) | −0.99[1] |
| Details | |
| Mass | 3.56±0.04[6] M☉ |
| Radius | 5.5[7] R☉ |
| Luminosity | 309[6] L☉ |
| Surface gravity (log g) | 2.87[8] cgs |
| Temperature | 10,495[6] K |
| Rotation | 27.2 days[8] |
| Rotational velocity (v sin i) | 160[6] km/s |
| Age | 252[9] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Omicron Hydrae (ο Hya) is the Bayer designation for a solitary[11] star in the equatorial constellation Hydra. At one time it bore the Flamsteed designation 25 Crateris, but this is no longer used by astronomers so as to avoid confusion.[12] With an apparent visual magnitude of 4.70,[3] this star is visible to the naked eye. Based upon an annual parallax shift of 7.27 mas,[2] it is located around 449 light years from the Sun.
This is a B-type main sequence star with a stellar classification of B9 V.[4] It has completed an estimated 98.4%±1.1% of its lifetime on the main sequence. With 3.56[6] times the mass of the Sun, it radiates 309 times the Sun's luminosity from its outer atmosphere at an effective temperature of 10,495 K.[6] The rate of spin is relatively high, with a projected rotational velocity of 160 km/s.[6]
References
- ↑ 1.0 1.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A. XHIP record for this object at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 3.0 3.1 3.2 3.3 Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data (SIMBAD), Bibcode: 1986EgUBV........0M.
- ↑ 4.0 4.1 Houk, N. (1982), Michigan Catalogue of Two-dimensional Spectral Types for the HD stars, 3, Ann Arbor, MI: Department of Astronomy, University of Michigan, Bibcode: 1982mcts.book.....H.
- ↑ Wielen, R. et al. (2000), "Sixth Catalogue of Fundamental Stars (FK6). Part III. Additional fundamental stars with direct solutions", Veröffentlichungen Astronomisches Rechen-Institut Heidelberg (Karlsruhe: Verlag G. Braun) 37 (37): pp. 1–308, ISBN 3-7650-0536-3, Bibcode: 2000VeARI..37....1W.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics 537: A120, doi:10.1051/0004-6361/201117691, Bibcode: 2012A&A...537A.120Z.
- ↑ Stassun, Keivan G. et al. (2019), "The Revised TESS Input Catalog and Candidate Target List", The Astronomical Journal 158 (4): 138, doi:10.3847/1538-3881/ab3467, Bibcode: 2019AJ....158..138S.
- ↑ 8.0 8.1 Oelkers, Ryan J.; Rodriguez, Joseph E.; Stassun, Keivan G.; Pepper, Joshua; Somers, Garrett; Kafka, Stella; Stevens, Daniel J.; Beatty, Thomas G. et al. (2018), "Variability Properties of Four Million Sources in the TESS Input Catalog Observed with the Kilodegree Extremely Little Telescope Survey", The Astronomical Journal 155 (1): 39, doi:10.3847/1538-3881/aa9bf4, Bibcode: 2018AJ....155...39O.
- ↑ Gontcharov, G. A. (2012), "Dependence of kinematics on the age of stars in the solar neighborhood", Astronomy Letters 38 (12): 771, doi:10.1134/S1063773712120031, Bibcode: 2012AstL...38..771G.
- ↑ "* omi Hya". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+omi+Hya.
- ↑ 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
- ↑ Wagman, M. (August 1987), "Flamsteed's Missing Stars", Journal for the History of Astronomy 18 (3): 216, doi:10.1177/002182868701800305, Bibcode: 1987JHA....18..209W.
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