Astronomy:12 Hydrae
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Hydra[1] |
| Right ascension | 08h 46m 22.54441s[2] |
| Declination | −13° 32′ 51.8051″[2] |
| Apparent magnitude (V) | 4.32[1] |
| Characteristics | |
| Evolutionary stage | red giant branch[2] |
| Spectral type | G8 IIIb CN-1[3] |
| B−V color index | 0.900±0.015[1] |
| Astrometry | |
| Radial velocity (Rv) | −8.5±0.7[1] km/s |
| Proper motion (μ) | RA: +10.316[2] mas/yr Dec.: −15.012[2] mas/yr |
| Parallax (π) | 15.8840 ± 0.3987[2] mas |
| Distance | 205 ± 5 ly (63 ± 2 pc) |
| Absolute magnitude (MV) | +0.26[4] |
| Orbit[5] | |
| Primary | Aa |
| Companion | Ab |
| Period (P) | 1,592±806 d |
| Semi-major axis (a) | 0.0116±0.057″ |
| Eccentricity (e) | 0.40±0.26 |
| Inclination (i) | 58±10° |
| Longitude of the node (Ω) | 91±16° |
| Periastron epoch (T) | 49,194±664 |
| Argument of periastron (ω) (secondary) | 103±34° |
| Details | |
| Mass | 1.83[6] M☉ |
| Radius | 10.8[7] R☉ |
| Luminosity | 71[8] L☉ |
| Surface gravity (log g) | 3.13[6] cgs |
| Temperature | 5,105[7] K |
| Metallicity [Fe/H] | −0.01[6] dex |
| Rotational velocity (v sin i) | 4.6±0.2[4] km/s |
| Age | 410[2] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
12 Hydrae is a probable astrometric binary[10] star system located 205 light years away from the Sun in the equatorial constellation of Hydra. It has the Bayer designation D Hydrae;[9] 12 Hydrae is the Flamsteed designation. This system is visible to the naked eye as a faint, yellow-hued star with a combined apparent visual magnitude of 4.32.[1] It is moving closer to the Earth with a heliocentric radial velocity of −8.5 km/s.[1]
This was found to be a double star by R. A. Rossiter in 1953,[11] with the magnitude 13.7 companion having an angular separation of 26.8″ along a position angle of 266°, as of 2016. The brighter, magnitude 4.32 component A is a spectroscopic binary. As of 2009, the orbital solution for this pair is of low quality, giving a period of roughly 4 years and an eccentricity of around 0.4.[5]
The primary component is an aging giant star with a stellar classification of G8 IIIb CN-1,[3] where the suffix notation indicates an underabundance of the cyanogen molecule. It is 410 million years old[2] with 1.8 times the mass of the Sun.[6] After exhausting the hydrogen at its core and evolving off the main sequence, the star has swollen to 11 times the Sun's radius.[7] It is radiating 71 times the luminosity of the Sun[8] from its enlarged photosphere at an effective temperature of 5,105 K.[7]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 3.0 3.1 Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series 71: 245, doi:10.1086/191373, Bibcode: 1989ApJS...71..245K
- ↑ 4.0 4.1 Ammler-von Eiff, Matthias; Reiners, Ansgar (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics 542: A116, doi:10.1051/0004-6361/201118724, Bibcode: 2012A&A...542A.116A.
- ↑ 5.0 5.1 Hartkopf, W. I. et al. (June 30, 2006), Sixth Catalog of Orbits of Visual Binary Stars, United States Naval Observatory, http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6, retrieved 2017-06-02.
- ↑ 6.0 6.1 6.2 6.3 Khalatyan, A.; Anders, F.; Chiappini, C.; Queiroz, A. B. A.; Nepal, S.; Dal Ponte, M.; Jordi, C.; Guiglion, G. et al. (2024). "Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost". Astronomy and Astrophysics 691: A98. doi:10.1051/0004-6361/202451427. Bibcode: 2024A&A...691A..98K.
- ↑ 7.0 7.1 7.2 7.3 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 Fetherolf, Tara; Pepper, Joshua; Simpson, Emilie; Kane, Stephen R.; Močnik, Teo; English, John Edward; Antoci, Victoria; Huber, Daniel et al. (2023). "Variability Catalog of Stars Observed during the TESS Prime Mission". The Astrophysical Journal Supplement Series 268 (1): 4. doi:10.3847/1538-4365/acdee5. Bibcode: 2023ApJS..268....4F.
- ↑ 9.0 9.1 "12 Hya". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=12+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.
- ↑ Rossiter, R. A. (February 1953), "Seventh list of new Southern double stars found at the Lamont-Hussey Observatory of the University of Michigan at Bloemfontein, South Africa.", Astronomical Journal 58: 29–30, doi:10.1086/106804, Bibcode: 1953AJ.....58...29R.
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