Zeta Hydri

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ζ Hydri
Hydrus constellation map.svg
Red circle.svg

Location of ζ Hydri (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Hydrus
Right ascension 02h 45m 32.63435s[1]
Declination −67° 36′ 59.8268″[1]
Apparent magnitude (V) 4.83[2]
Spectral type A2IV[2]
U−B color index +0.09[3]
B−V color index +0.06[3]
Radial velocity (Rv) +3.60[4] km/s
Proper motion (μ) RA: +66.41[1] mas/yr
Dec.: +43.38[1] mas/yr
Parallax (π) 11.47 ± 0.17[1] mas
Distance 284 ± 4 ly
(87 ± 1 pc)
Absolute magnitude (MV) 0.13[2]
Mass 2.44[5] M
Radius 3.9[5] R
Luminosity 79.55[2] L
Surface gravity (log g) 3.72[6] cgs
Temperature 9,144[6] K
Rotational velocity (v sin i) 116[6] km/s
Other designations
FK5 2191, GC 3354, HIP 12876, HR 837, HD 17566, SAO 248644
Database references

Zeta Hydri (ζ Hyi) is a class A2IV[2] (white subgiant) star in the constellation Hydrus. Its apparent magnitude is 4.83[2] and it is approximately 284 light years away based on parallax.[1]


  1. ^ a b c d e f Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752free to read. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ a b c d e f Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971free to read. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015.  Vizier catalog entry
  3. ^ a b Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42: 443. Bibcode:2014JAVSO..42..443M. Vizier catalog entry
  4. ^ Wilson, R. E. (1953). General Catalogue of Stellar Radial Velocities. Carnegie Institute of Washington. Bibcode:1953GCRV..C......0W. LCCN 54001336. 
  5. ^ a b Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555. arXiv:astro-ph/9911002free to read. Bibcode:1999A&A...352..555A.  Vizier catalog entry
  6. ^ a b c David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154free to read. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146.  Vizier catalog entry