KU Hydrae

KU Hydrae is a binary star in the constellation Hydra. The primary star is an Alpha2 Canum Venaticorum variable with its apparent magnitude varying from 0.05 magnitudes over a period of 33.97 days.[6]

KU Hydrae

Observation data Epoch J2000      Equinox J2000
Constellation	Hydra[1]
Right ascension	09^h 22^m 50.856^s[2]
Declination	−09° 50′ 19.66″[2]
Apparent magnitude (V)	6.75[3]
Characteristics
Spectral type	Ap EuCrSr[4]
U−B color index	+0.11[5]
B−V color index	+0.22[5]
Variable type	α^2 CVn
Astrometry
Radial velocity (Rv)	19.6 ± 5.0 km/s
Proper motion (μ)	RA: −27.94 ± 0.61[2] mas/yr Dec.: −13.01 ± 0.36[2] mas/yr
Parallax (π)	6.92 ± 0.61[2] mas
Distance	470 ± 40 ly (140 ± 10 pc)
Orbit[6]
Companion	KU Hya B
Period (P)	53.199 ± 0.193 yr
Semi-major axis (a)	0.165 ± 0.011″
Eccentricity (e)	0.038 ± 0.037
Inclination (i)	67.1 ± 4.1°
Longitude of the node (Ω)	23.7 ± 3.6°
Periastron epoch (T)	1957.346 ± 0.572
Details[6]
KU Hya A
Mass	2.07 M☉
KU Hya B
Mass	2.05 M☉
Other designations
KU Hya, BD−09° 2816, HD 81009, HIP 45999, HR 3724, SAO 136799,[4] A 1342[7]
Database references
SIMBAD	data

This star was discovered to be a visual binary star by Robert Grant Aitken in 1906 and was given the double star designation A 1342.[7] Additional measurements of the position angle and angular separation showed a rapid orbital motion.[8]

References

1. Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific. 99 (617): 695–699. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Vizier query form
2. 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.Vizier catalog entry
3. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
4. "V* KU Hya". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2014-09-01.
5. Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
6. Rica Romero, F. M. (2010). "Orbital elements for eight binaries. Study of the nature of wide components. I" (PDF). Revista Mexicana de Astronomía y Astrofísica. 46: 263–277. Bibcode:2010RMxAA..46..263R.
7. Aitken, Robert Grant (1907). "Two hundred and fifty new double stars: tenth list". Lick Observatory Bulletin. 4 (109): 101–106. Bibcode:1907LicOB...4..101A. doi:10.5479/ADS/bib/1907LicOB.4.101A.
8. Aitken, Robert Grant (1929). "Measures of 296 A double stars". Lick Observatory Bulletin. 14 (413): 62–87. Bibcode:1929LicOB..14...62A. doi:10.5479/ADS/bib/1929LicOB.14.62A.