Astronomy:Zeta Hydri
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Hydrus |
| Right ascension | 02h 45m 32.63435s[1] |
| Declination | −67° 36′ 59.8268″[1] |
| Apparent magnitude (V) | 4.83[2] |
| Characteristics | |
| Spectral type | A2IV[2] |
| U−B color index | +0.09[3] |
| B−V color index | +0.06[3] |
| Astrometry | |
| Radial velocity (Rv) | +3.60[4] km/s |
| Proper motion (μ) | RA: +66.41[1] mas/yr Dec.: +43.38[1] mas/yr |
| Parallax (π) | 11.47 ± 0.17[1] mas |
| Distance | 284 ± 4 ly (87 ± 1 pc) |
| Absolute magnitude (MV) | 0.13[2] |
| Details | |
| Mass | 2.44[5] M☉ |
| Radius | 3.9[5] R☉ |
| Luminosity | 79.55[2] L☉ |
| Surface gravity (log g) | 3.72[6] cgs |
| Temperature | 9,144[6] K |
| Rotational velocity (v sin i) | 116[6] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Zeta Hydri, Latinized from ζ Hydri, is a single,[7] white-hued star in the southern constellation of Hydrus. It is faintly visible to the naked eye with an apparent magnitude of 4.83.[2] This distance to this star can be estimated from its annual parallax shift of 11.47 mas,[1] showing it to be about 284 light years away. It is moving further away from the Sun with a radial velocity of +3.6 km/s.[4]
The spectrum of this star matches a stellar classification of A2 IV,[2] suggesting it is a subgiant star that is in the process of evolving away from the main sequence as the supply of hydrogen at its core becomes exhausted. It has a high rate of spin, showing a projected rotational velocity of 116 km/s.[6] This is giving the star a slight oblate shape with an equatorial bulge that is 5% larger than the polar radius.[8] It has 2.4 times the mass of the Sun and nearly four times the Sun's radius.[5] Zeta Hydri is radiating 80[2] times the Sun's luminosity into space from its photosphere at an effective temperature of 9,144 K.[6]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 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. Vizier catalog entry
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A. Vizier catalog entry
- ↑ 3.0 3.1 Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers 42 (2): 443. Bibcode: 2014JAVSO..42..443M.Vizier catalog entry
- ↑ 4.0 4.1 Wilson, R. E. (1953). "General Catalogue of Stellar Radial Velocities". Carnegie Institute Washington D.C. Publication (Carnegie Institution of Washington). Bibcode: 1953GCRV..C......0W.
- ↑ 5.0 5.1 5.2 Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics 352: 555–562. Bibcode: 1999A&A...352..555A. Vizier catalog entry
- ↑ 6.0 6.1 6.2 6.3 6.4 David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal 804 (2): 146. doi:10.1088/0004-637X/804/2/146. Bibcode: 2015ApJ...804..146D. Vizier catalog entry
- ↑ 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.
- ↑ Belle, G. T. (2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review 20 (1): 51. doi:10.1007/s00159-012-0051-2. Bibcode: 2012A&ARv..20...51V.
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