Beta Hydrae
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | ||
Constellation | Hydra | |
Component | A | B |
Right ascension | 11h 52m | 11h 52m |
54.521s | 54.550s | |
Declination | −33° 54′[1] | −33° 54′[2] |
29.25″ | 28.73″ | |
Apparent magnitude (V) | 4.67[3] | 5.47[3] |
4.276(combined)[4] | ||
Characteristics | ||
Spectral type | B9IIIsp...[4] | |
U-B color index | −0.33[5] | |
B-V color index | −0.10[5] | |
R-I color index | −0.08[5] | |
Variable type | ACV[6] | |
Astrometry | ||
Radial velocity (Rv) | −1 ± 5[4] km/s | |
Proper motion: | ||
RA (μα cos δ) | −58.02 [1] mas/yr | −52.70[2] mas/yr |
Dec. (μδ) | 2.40[1] mas/yr | −8.94[2] mas/yr |
Parallax (π) | 8.93 ± 0.88[4] mas | |
Distance | 370 ± 40 ly (110 ± 10 pc) | |
Absolute magnitude (MV) | −1.0[7] | |
Details | ||
Mass | 3.36 ± 0.15[8] M☉ | ~3[9] M☉ |
Radius | 4.0 ± 0.6[8] R☉ | |
Luminosity (bolometric) | 210[9] L☉ | |
Temperature | 11,100[8] K | |
Age | 2.2 × 108 [9]y | |
Database references | ||
SIMBAD | data | |
Other designations | ||
Beta Hydrae (Beta Hya, β Hydrae, β Hya) is a double star in the constellation of Hydra.[4] Its overall apparent visual magnitude varies by 0.04 magnitudes with a period of 2.344 days, and is approximately 4.27 at maximum brightness.[10] The brighter star in the double is a giant Bp star which has been classified as an α2 Canum Venaticorum variable.[4][6]
Beta Hydrae was a latter designation of 28 Crateris.[11]
References
- ↑ 1.0 1.1 1.2 HIP 57936, record for component 1, Hipparcos catalogue; CDS ID I/239.
- ↑ 2.0 2.1 2.2 HIP 57936, record for component 2, Hipparcos catalogue; CDS ID I/239.
- ↑ 3.0 3.1 3.2 Entry 11529-3354, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line September 23, 2008.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 V* alf Dor -- Variable Star, database entry, SIMBAD. Accessed on line September 3, 2008.
- ↑ 5.0 5.1 5.2 HR 4552, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 23, 2008.
- ↑ 6.0 6.1 Notes, Entry 11529-3354, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line September 23, 2008.
- ↑ From apparent magnitude and parallax.
- ↑ 8.0 8.1 8.2 North, P. (June 1998), "Do SI stars undergo any rotational braking?", Astronomy and Astrophysics 334: 181–187, arXiv:astro-ph/9802286, Bibcode:1998A&A...334..181N
- ↑ 9.0 9.1 9.2 Beta Hydrae, Stars, Jim Kaler. Accessed on line September 23, 2008.
- ↑ bet Hya, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line September 23, 2008.
- ↑ Wagman, M. (August 1987). "Flamsteed's Missing Stars". Journal for the History of Astronomy, Vol.18, NO. 3/AUG, P.209, 1987 18: 216. Bibcode:1987JHA....18..209W.
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