Delta Hydrae

Delta Hydrae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hydra
Right ascension 08h 37m 39.36627s[1]
Declination +05° 42′ 13.6057″[1]
Apparent magnitude (V) 4.146[2]
Characteristics
Spectral type A1 Vnn[3]
U−B color index +0.003[2]
B−V color index +0.008[2]
Astrometry
Radial velocity (Rv)4.10[4] km/s
Proper motion (μ) RA: −70.19[1] mas/yr
Dec.: −7.90[1] mas/yr
Parallax (π)20.34 ± 0.63 mas[1]
Distance160 ± 5 ly
(49 ± 2 pc)
Absolute magnitude (MV)+0.68[5]
Details
Mass2.88[6] M☉
Radius2.7[7] R☉
Luminosity42.7[8] L☉
Temperature11,055±376[6] K
Rotational velocity (v sin i)285[3] km/s
Age244[6] Myr
Other designations
δ Hya, 4 Hydrae, BD+06° 2001, FK5 1223, HD 73262, HIP 42313, HR 3410, SAO 116965.[9]
Database references
SIMBADdata

Delta Hydrae, Latinized from δ Hydrae, is a double star in the equatorial constellation of Hydra. It is visible to the naked eye with an apparent visual magnitude of 4.146.[2] Based upon an annual parallax shift of 20.34 mas, it is located about 160 light years from the Sun.

This is a double star[10] with an angular separation of 2.6±0.1 arc second along a position angle of 265.1°±1.0°, as of 2003.[11] The brighter component is an A-type main sequence star with a stellar classification of A1 Vnn.[3] It is spinning rapidly with a projected rotational velocity of 285 km/s. This is giving the star an oblate shape with an equatorial bulge that is 20% larger than the polar radius.[3] It has an estimated 2.88[6] times the mass of the Sun and 2.7[7] times the Sun's radius.[7] The star is about 244 million years old and it radiates 42.7[8] times the solar luminosity from its outer atmosphere at an effective temperature of 11,055 K.[6]

The companion has a visual magnitude of 11.15.[10] X-ray emissions have been detected from this location in space, which may be coming from a companion star.[11]

  1. ^ a b c d e 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 Cousins1984 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference belle2012 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 David2015 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference cadars2001 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Mcdonald2012 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. ^ a b Cite error: The named reference WDSC2014 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference DeRosa2011 was invoked but never defined (see the help page).