Upsilon2 Hydrae

For other stars with this Bayer designation, see υ Hydrae.
Upsilon2 Hydrae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hydra
Right ascension 10h 05m 07.46888s[1]
Declination −13° 03′ 52.6561″[1]
Apparent magnitude (V) 4.59[2]
Characteristics
Spectral type B9 III-IV[3]
U−B color index −0.27[2]
B−V color index −0.08[2]
Astrometry
Radial velocity (Rv)+24.3±2.6[4] km/s
Proper motion (μ) RA: −39.39[1] mas/yr
Dec.: +19.65[1] mas/yr
Parallax (π)10.40 ± 0.23 mas[1]
Distance314 ± 7 ly
(96 ± 2 pc)
Absolute magnitude (MV)−0.31[5]
Details
Mass3.29±0.03[6] M☉
Radius3.2[7] R☉
Luminosity182[6] L☉
Surface gravity (log g)3.87[8] cgs
Temperature11758±400[8] K
Rotational velocity (v sin i)58[8] km/s
Age97[8] Myr
Other designations
υ2 Hya, 40 Hydrae, BD−12°3073, FK5 1261, HD 87504, HIP 49402, HR 3970, SAO 155713[9]
Database references
SIMBADdata

Upsilon2 Hydrae, Latinised from υ2 Hydrae, is a solitary[10] star in the equatorial constellation of Hydra. Visible to the naked eye, it is photometrically stable[11] with an apparent visual magnitude of 4.59.[2] Based upon an annual parallax shift of 10.40 mas as seen from Earth,[1] it is located about 314 light-years from the Sun.

This is a B-type star with a stellar classification of B9 III-IV,[3] showing partial traits of a subgiant and giant star in its spectrum. However, Zorec and Royer (2012) estimate the star still only 79% of the way through its life span on the main sequence.[6] With an age of around 97 million years,[8] it is spinning with a projected rotational velocity of 58 km/s.[8] The star has an estimated 3.29[6] times the mass of the Sun and around 3.2[7] times the Sun's radius. It is radiating 182[6] times the solar luminosity from its photosphere at an effective temperature of about 11,758 K.[8]

  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 Mermilliod1986 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference houk1978 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ a b c d e Cite error: The named reference Zorec2012 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference PasinettiFracassini2001 was invoked but never defined (see the help page).
  8. ^ a b c d e f g Cite error: The named reference David2015 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Adelman2000 was invoked but never defined (see the help page).