Alpha Hydri
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Hydrus |
| Right ascension | 01h 58m 46.1935s[1] |
| Declination | −61° 34′ 11.493″[1] |
| Apparent magnitude (V) | +2.90[2] |
| Characteristics | |
| Spectral type | F0IV[2] |
| U−B color index | +0.189[3] |
| B−V color index | +0.290[3] |
| Astrometry | |
| Radial velocity (Rv) | +7[4] km/s |
| Proper motion (μ) | RA: 262.54[1] mas/yr Dec.: 26.89[1] mas/yr |
| Parallax (π) | 45.74 ± 0.55[1] mas |
| Distance | 71.3 ± 0.9 ly (21.9 ± 0.3 pc) |
| Absolute magnitude (MV) | 1.153[5] |
| Details | |
| Radius | 1.8[6] R☉ |
| Temperature | 7,077[5] K |
| Metallicity | ![\begin{smallmatrix}\left[\frac{Fe}{H}\right]\ =\ 0.11\end{smallmatrix}](/2012-wikipedia_en_all_nopic_01_2012/I/f52d600e1ad30e6b6576772f80db1288.png) [5] |
| Rotational velocity (v sin i) | 118[7] km/s |
| Age | 8.1 × 108[5] years |
| Other designations | |
Alpha Hydri (α Hyi, α Hydri) is a star in the constellation Hydrus. It is sometimes informally known as the Head of Hydrus.[8] It should not be confused with Alpha Hydrae (Alphard) in the constellation Hydra. Alpha Hydri is one of only three stars in the constellation Hydrus that is above the fourth visual magnitude. This star can be readily located as it lies to the south and west of the prominent star Achernar in the constellation Eridanus.[9]
Alpha Hydri belongs to spectral class F0V and has apparent magnitude +2.9. It is 1.8 times the radius of the Sun,[6] about 810 million years old,[5] and is approximately 71 light years from Earth. The space velocity components of this star are U = −14, V = −14 and W = -2 km/s.[10]
X-ray source
Alpha Hydri emits X-rays similar to Altair.[11]
See also
References
- ^ a b c d e Perryman, M. A. C. et al. (1997), "The Hipparcos Catalogue", Astronomy & Astrophysics 323: L49–L52, Bibcode 1997A&A...323L..49P
- ^ a b c "LTT 1059". SIMBAD. Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=LTT+1059. Retrieved 2009-10-13.
- ^ a b Gutierrez-Moreno, Adelina; et al. (1966). A System of photometric standards. 1. Publicaciones Universidad de Chile, Department de Astronomy. pp. 1–17. Bibcode 1966PDAUC...1....1G.
- ^ Wilson, R. E. (1953). General Catalogue of Stellar Radial Velocities. Carnegie Institute of Washington D.C.. http://adsabs.harvard.edu/abs/1953GCRV..C......0W. Retrieved 2009-09-08.
- ^ a b c d e Lachaume, R.; et al. (August 1999). "Age determinations of main-sequence stars: combining different methods". Astronomy and Astrophysics 348: 897–909. Bibcode 1999A&A...348..897L.
- ^ a b Wesselink, A. J.; Paranya, K.; DeVorkin, K. (November 1972). "Catalogue of stellar dimensions". Astronomy and Astrophysics Supplement 7: 257. Bibcode 1972A&AS....7..257W. Via Vizier table II/224/cadars.
- ^ Royer, F.; et al. (October 2002). "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i". Astronomy and Astrophysics 393 (3): 897−911. arXiv:astro-ph/0205255. Bibcode 2002A&A...393..897R. doi:10.1051/0004-6361:20020943.
- ^ Allen, Richard Hinkley (1963). Star Names, Their Lore and Meaning. New York: Dover. p. 377. ISBN 0-486-21079-0.
- ^ Moore, Patrick (2005). The observer's year: 366 nights of the universe (2nd ed.). Springer. p. 4. ISBN 1-85233-884-9.
- ^ Gliese, W. (1969). Catalogue of Nearby Stars. Karlsruhe.
- ^ Schmitt JHMM, Golub L, Harnden FR Jr, Maxson CW, Rosner R, Vaiana GS (March 1985). "An Einstein Observatory X-ray survey of main-sequence stars with shallow convection zones". Ap J 290 (Part 1): 307–20. Bibcode 1985ApJ...290..307S. doi:10.1086/162986.
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