μ Hydrae, Latinised as Mu Hydrae, is a solitary,[8] orange-hued star in the equatorial constellation of Hydra. It is visible to the naked eye with an apparent visual magnitude of 3.83.[2] Positioned just 1.8° to the south-southwest is the planetary nebula NGC 3242.[9] Mu Hydrae has an annual parallax shift of 13.93 mas,[1] which yields a distance estimate of 234 light years.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Hydra |
| Right ascension | 10h 26m 05.42630s[1] |
| Declination | −14° 19′ 56.2675″[1] |
| Apparent magnitude (V) | 3.83[2] |
| Characteristics | |
| Spectral type | K4 III[3] |
| U−B color index | +1.83[2] |
| B−V color index | +1.47[2] |
| Variable type | Suspected[4] |
| Astrometry | |
| Radial velocity (Rv) | +40.81±0.36[5] km/s |
| Proper motion (μ) | RA: −129.17[1] mas/yr Dec.: −79.76[1] mas/yr |
| Parallax (π) | 13.93 ± 0.18 mas[1] |
| Distance | 234 ± 3 ly (71.8 ± 0.9 pc) |
| Absolute magnitude (MV) | −0.45[6] |
| Details[5] | |
| Radius | 45 R☉ |
| Luminosity | 332[6] L☉ |
| Surface gravity (log g) | 1.5 cgs |
| Temperature | 3,999±8 K |
| Metallicity [Fe/H] | −0.12 dex |
| Rotational velocity (v sin i) | 6.0 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is an evolved K-type giant star with a stellar classification of K4 III,[3] having used up its core hydrogen and has expanded to around 45 times the radius of the Sun.[5] It is a suspected variable star, with a brightness that varies about 0.03 in magnitude.[4] The relatively cool outer atmosphere has an effective temperature of 3999 K.[5]
References
edit- ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
- ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
- ^ a b Houk, N.; Smith-Moore, M. (1988), University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Declinations -26°.0 to -12°.0, vol. 4, Department of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
- ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009), "General Catalogue of Variable Stars", Vizier Online Data Catalog, 1, Bibcode:2009yCat....102025S.
- ^ a b c d Massarotti, Alessandro; et al. (January 2008), "Rotational and radial velocities for a sample of 761 HIPPARCOS giants and the role of binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209, S2CID 121883397.
- ^ a b 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.
- ^ "* mu. Hya". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-01-06.
- ^ 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
- ^ O'Meara, Steve (2007), Herschel 400 Observing Guide, Cambridge University Press, p. 107, ISBN 978-0521858939.