Kappa Hydrae

κ Hydrae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hydra
Right ascension 09h 40m 18.36496s[1]
Declination −14° 19′ 56.2675″[1]
Apparent magnitude (V) 5.06[2]
Characteristics
Spectral type B4 IV/V[3]
U−B color index −0.57[2]
B−V color index −0.15[2]
Variable type Suspected[4][5]
Astrometry
Radial velocity (Rv)20.6±2.0[6] km/s
Proper motion (μ) RA: −23.41[1] mas/yr
Dec.: −21.10[1] mas/yr
Parallax (π)7.48 ± 0.30 mas[1]
Distance440 ± 20 ly
(134 ± 5 pc)
Absolute magnitude (MV)−0.98[7]
Details
Mass5.0±0.1[3] M☉
Radius3.4[8] R☉
Luminosity328[9] L☉
Temperature16,150±920[10] K
Rotational velocity (v sin i)115.0[11] km/s
Age30.7±3.3[3] Myr
Other designations
κ Hya, 38 Hydrae, BD−13° 2917, FK5 364, HD 83754, HIP 47452, HR 3849, SAO 155388.[12]
Database references
SIMBADdata

κ Hydrae, Latinised as Kappa Hydrae, is a solitary[13] star in the equatorial constellation of Hydra. Its apparent visual magnitude is 5.06,[2] which is bright enough to be faintly visible to the naked eye. The distance to this star is around 135 pc (440 ly), based upon an annual parallax shift of 7.48 mas.[1] It may be a variable star, meaning it undergoes repeated fluctuations in brightness by at least 0.1 magnitude.[5]

This is an evolving B-type star with a stellar classification of B4 IV/V,[3] having a luminosity class intermediate between a subgiant and a giant star. It has an estimated five[3] times the mass of the Sun and 3.4 times the Sun's radius.[8] Kappa Hydrae has a high rate of spin with a projected rotational velocity of 115.0 km/s,[11] and is only about 31 million years old.[3] The star radiates 328 times the solar luminosity from its outer atmosphere[9] at an effective temperature of 16,150 K.[10]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Nicolet1978 was invoked but never defined (see the help page).
  3. ^ a b c d e f Cite error: The named reference Tetzlaff2011 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference gcvs2009 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Rufener1982 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Zorec1991 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference PasinettiFracassini2001 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Mcdonald2012 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Soubiran2010 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference Abt2002 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).