Beta Hydrae

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β 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 α cos δ)  −58.02 [1] mas/yr  −52.70[2] mas/yr 
Dec. δ)  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
β Hya, Beta Hydrae, Beta Hya, HJ 4478AB, CCDM J11529-3354AB, CD−33 8018, CPD−33 3159, GC 16258, HD 103192, HIP 57936, HR 4552, IDS 11479-3321 AB, PPM 289465, SAO 202901, WDS 11529-3354AB.[4][3]

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[edit]

  1. ^ a b c HIP 57936, record for component 1, Hipparcos catalogue; CDS ID I/239.
  2. ^ a b c HIP 57936, record for component 2, Hipparcos catalogue; CDS ID I/239.
  3. ^ a b c Entry 11529-3354, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line September 23, 2008.
  4. ^ a b c d e f g V* alf Dor -- Variable Star, database entry, SIMBAD. Accessed on line September 3, 2008.
  5. ^ a b c 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. ^ a b Notes, Entry 11529-3354, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line September 23, 2008.
  7. ^ From apparent magnitude and parallax.
  8. ^ a b c 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. ^ a b c Beta Hydrae, Stars, Jim Kaler. Accessed on line September 23, 2008.
  10. ^ 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.
  11. ^ 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.