Astronomy:Eta1 Hydri
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Hydrus |
| Right ascension | 01h 52m 34.78591s[1] |
| Declination | −67° 56′ 40.1823″[1] |
| Apparent magnitude (V) | 6.76[2] |
| Characteristics | |
| Spectral type | B9 V[3] |
| B−V color index | −0.050±0.002[4] |
| Astrometry | |
| Radial velocity (Rv) | +15.0±3.0[2] km/s |
| Proper motion (μ) | RA: +18.270[1] mas/yr Dec.: −8.948[1] mas/yr |
| Parallax (π) | 5.2719 ± 0.0548[1] mas |
| Distance | 619 ± 6 ly (190 ± 2 pc) |
| Absolute magnitude (MV) | +0.77[5] |
| Details | |
| Luminosity | 91[6] L☉ |
| Temperature | 9,816[6] K |
| Age | 311[5] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Eta1 Hydri, Latinized from η1 Hydri, is a blue-white hued star in the southern constellation of Hydrus. It has an apparent visual magnitude of 6.76,[2] which may be too faint to be visible to the naked eye. Based upon an annual parallax shift of 5.27 mas as measured from Earth,[1] the system is located about 619 light years distant from the Sun. At that distance, the visual magnitude of the star is diminished by 0.10 magnitudes of extinction due to interstellar dust.[5] The star is drifting further away with a heliocentric radial velocity of +15 km/s.[2]
This is a B-type main-sequence star with a stellar classification of B9 V[3] that was suspected in 1939 by Herbert Schneller of being variable.[8] However, this may have been based on a photographic plate that was later rejected.[9] It is listed in the General Catalogue of Variable Stars, but marked as probably constant.[10]
The star is about 311[5] million years old and is radiating 91 times the luminosity of the Sun from its photosphere at an effective temperature of 9,816 K.[6]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 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.
- ↑ 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.
- ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 5.0 5.1 5.2 5.3 Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters 38 (11): 694–706, doi:10.1134/S1063773712110035, Bibcode: 2012AstL...38..694G.
- ↑ 6.0 6.1 6.2 McDonald, I. et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society 427 (1): 343–57, doi:10.1111/j.1365-2966.2012.21873.x, Bibcode: 2012MNRAS.427..343M.
- ↑ "eta1 Hyi". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=eta1+Hyi.
- ↑ "Eta1 Hydri", International Variable Star Index (AAVSO), January 4, 2010, http://www.aavso.org/vsx/index.php?view=detail.top&oid=16482, retrieved 12 September 2013.
- ↑ Sahade, Jorge; Albarracín, Julio (March 1950), "Spectrographic Observations of the Star η1 Hydri", Astrophysical Journal 111: 442, doi:10.1086/145283, Bibcode: 1950ApJ...111..442S.
- ↑ Samus, N. N. et al. (2009), "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)", VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S 1: B/gcvs, Bibcode: 2009yCat....102025S.
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