Nu Hydrae

Nu Hydrae
Location of ν Hydrae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Hydra
Right ascension 10h 49m 37.48875s[1]
Declination −16° 11′ 37.1360″[1]
Apparent magnitude (V) 3.115[2]
Characteristics
Spectral type K0/K1 III[3]
U−B color index +1.305[2]
B−V color index +1.239[2]
Astrometry
Radial velocity (Rv)−1.37±0.25[4] km/s
Proper motion (μ) RA: +93.35[1] mas/yr
Dec.: +198.88[1] mas/yr
Parallax (π)23.7940 ± 0.1695 mas[5]
Distance137.1 ± 1.0 ly
(42.0 ± 0.3 pc)
Absolute magnitude (MV)−0.11[6]
Details
Mass2.0[7] M☉
Radius21[4] R☉
Luminosity151[4] L☉
Surface gravity (log g)2.3[4] cgs
Temperature4,335[4] K
Metallicity [Fe/H]−0.30[4] dex
Rotational velocity (v sin i)5.3[4] km/s
Other designations
ν Hya, 4 Crateris, BD−15 3138, FK5 410, HD 93813, HIP 52943, HR 4232, SAO 156256[8]
Database references
SIMBADdata

Nu Hydrae, Latinized from ν Hydrae, is an orange-hued star in the constellation Hydra, near the border with the neighboring constellation of Crater. It has an apparent visual magnitude of 3.115,[2] which is bright enough to be seen with the naked eye. Based upon parallax measurements, this star is located at a distance of about 137 light-years (42 parsecs) from the Earth.[1]

The spectrum of this star matches a stellar classification of K0/K1 III,[3] where the luminosity class of 'III' indicates this is a giant star that has exhausted the supply of hydrogen at its core and evolved away from the main sequence. The radius of this star has expanded to 21 times the Sun's radius[4] and it radiates about 151 times the luminosity of the Sun.[4] This expanded outer envelope has an effective temperature of about 4,335 K,[4] giving it the characteristic orange hue of a K-type star.[9]

Nu Hydrae is an X-ray emitter with an estimated luminosity of 6.6 × 1028 erg s−1 in the X-ray band.[7] The abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity,[4] is about half that in the Sun.[a] It has a relatively high proper motion across the celestial sphere,[8] suggesting that it has a peculiar velocity roughly three times higher than its neighbors.[10]

Nu Hydrae was a later designation of 4 Crateris.[11]

  1. ^ a b c d e Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference sps1966 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference aaa339_858 was invoked but never defined (see the help page).
  4. ^ a b c d e f g h i j k Cite error: The named reference aj135_1_209 was invoked but never defined (see the help page).
  5. ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  6. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference aaa352_217 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference csiro was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference kaler was invoked but never defined (see the help page).
  11. ^ Wagman, M. (August 1987). "Flamsteed's Missing Stars". Journal for the History of Astronomy. 18 (3): 215. Bibcode:1987JHA....18..209W. doi:10.1177/002182868701800305. S2CID 118445625.


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