Astronomy:Gamma Hydri
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Hydrus |
| Right ascension | 03h 47m 14.34062s[1] |
| Declination | −74° 14′ 20.2686″[1] |
| Apparent magnitude (V) | 3.26[2] |
| Characteristics | |
| Spectral type | M1 III[3] |
| U−B color index | +1.98[4] |
| B−V color index | +1.62[4] |
| Astrometry | |
| Radial velocity (Rv) | +15.8±0.6[5] km/s |
| Proper motion (μ) | RA: +50.85[1] mas/yr Dec.: +114.74[1] mas/yr |
| Parallax (π) | 15.24 ± 0.11[1] mas |
| Distance | 214 ± 2 ly (65.6 ± 0.5 pc) |
| Absolute magnitude (MV) | −0.83[6] |
| Details[7] | |
| Mass | 1.0 M☉ |
| Radius | 62±1 R☉ |
| Luminosity | 513 L☉ |
| Surface gravity (log g) | 0.84 cgs |
| Temperature | 3499 K |
| Metallicity [Fe/H] | 0.0 dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
γ Hydri, Latinised as Gamma Hydri, is a solitary,[9] red-hued star in the constellation Hydrus. It has an apparent visual magnitude of 3.26,[2] making it easily visible to the naked eye at night. Based upon an annual parallax shift of 15.24 mas as measured from Earth,[1] the system is located about 214 light-years from the Sun.
This is an evolved red giant star with a stellar classification of M1 III,[3] and is most likely on the asymptotic giant branch of the HR diagram.[10] It is a semiregular variable that pulsates between magnitudes 3.26 and 3.33, although its period is not known precisely.[11] It has about the same mass as the Sun, but has expanded to around 62 times the Sun's radius. The star is radiating 513 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,499 K.[7]
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.
- ↑ 2.0 2.1 Ducati, J. R. (2002), "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system", CDS/ADC Collection of Electronic Catalogues 2237, Bibcode: 2002yCat.2237....0D.
- ↑ 3.0 3.1 Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode: 1978mcts.book.....H.
- ↑ 4.0 4.1 Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99): 99, Bibcode: 1966CoLPL...4...99J.
- ↑ 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, doi:10.1051/0004-6361/201219219, A61, Bibcode: 2012A&A...546A..61D.
- ↑ Cardini, D. (January 2005), "Mg II chromospheric radiative loss rates in cool active and quiet stars", Astronomy and Astrophysics 430: 303–311, doi:10.1051/0004-6361:20041440, Bibcode: 2005A&A...430..303C.
- ↑ 7.0 7.1 Cruzalèbes, P. et al. (September 2013), "Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI/AMBER", Monthly Notices of the Royal Astronomical Society 434 (1): 437–450, doi:10.1093/mnras/stt1037, Bibcode: 2013MNRAS.434..437C.
- ↑ "gam Hyi". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=gam+Hyi.
- ↑ 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.
- ↑ Eggen, O. J. (1992), "Asymptotic giant branch stars near the sun", The Astronomical Journal 104: 275, doi:10.1086/116239, Bibcode: 1992AJ....104..275E.
- ↑ "Long-term Photometry and Periods for 261 Nearby Pulsating M Giants", Monthly Notices of the Royal Astronomical Society 400 (4): 1945–61, 2009, doi:10.1111/j.1365-2966.2009.15588.x, Bibcode: 2009MNRAS.400.1945T.
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