| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Hydra |
| Right ascension | 08 40 01.47182 |
| Declination | −12° 28′ 31.3433″ |
| Apparent magnitude (V) | 4.98 |
| Characteristics | |
| Evolutionary stage | giant |
| Spectral type | K3 III |
| B−V color index | 1.415±0.001 |
| Astrometry | |
| Radial velocity (Rv) | −7.8±0.6 km/s |
| Proper motion (μ) | RA: −81.619 mas/yr Dec.: −1.646 mas/yr |
| Parallax (π) | 8.7394 ± 0.1769 mas |
| Distance | 373 ± 8 ly (114 ± 2 pc) |
| Absolute magnitude (MV) | −0.40 |
| Details | |
| Radius | 32.7+0.5 −2.6 R☉ |
| Luminosity | 267±6 L☉ |
| Surface gravity (log g) | 1.91 cgs |
| Temperature | 4,080+173 −30 K |
| Metallicity | −0.21 dex |
| Other designations | |
| a Hya, 6 Hya, BD−11°2420, HD 73840, HIP 42509, HR 3431, SAO 154515 | |
| Database references | |
| SIMBAD | data |
6 Hydrae is a single star in the equatorial constellation of Hydra, located 373 light-years away from the Sun. It has the Bayer designation a Hydrae; 6 Hydrae is the Flamsteed designation. This object is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.98. It is moving closer to the Earth with a heliocentric radial velocity of −8 km/s. Eggen (1995) listed it as a proper motion candidate for membership in the IC 2391 supercluster.
This is an aging giant star with a stellar classification of K3 III, which indicates it has exhausted the hydrogen at its core and evolved away from the main sequence. As a consequence, it has expanded to 33 times the radius of the Sun. The star is radiating 267 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,080 K.
References
- ^ 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.
- ^ 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.
- ^ Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
- ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
- ^ McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", Astrophysical Journal Supplement Series, 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527.
- ^ "6 Hya". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-04-23.
- Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
- Eggen, Olin J. (December 1995), "Reality Tests of Superclusters in the Young Disk Population", Astronomical Journal, 110: 2862, Bibcode:1995AJ....110.2862E, doi:10.1086/117734.
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