HR 4458

From Wikipedia, the free encyclopedia
Jump to: navigation, search
HR 4458 A/B
Observation data
Epoch J2000      Equinox J2000
Constellation Hydra
Right ascension 11h 34m 29.4871s
Declination −32° 49′ 52.823″
Apparent magnitude (V) 5.98/15
Spectral type K0 V / M? V
U−B color index 0.33
B−V color index 0.80
V−R color index 0.44
R−I color index 0.40
Variable type None
Radial velocity (Rv) -22.6 km/s
Proper motion (μ) RA: -670.99 mas/yr
Dec.: 823.89 mas/yr
Parallax (π) 104.84 ± 0.81 mas
Distance 31.1 ± 0.2 ly
(9.54 ± 0.07 pc)
Absolute magnitude (MV) 6.09/15
Radius 0.84/0.15[1] R
Surface gravity (log g) 4.6[2]/– cgs
Temperature 5400[2]/2960[1] K
Metallicity [Fe/H] = -0.26[2]
Age (4.6–5.8) × 109[3] years
Other designations
Database references

HR 4458 (289 G. Hydrae) is a binary star system in the constellation Hydra. At a distance of 31 light years, they are the closest stars to the solar system within this constellation. The A star is an orange dwarf star of class K0, whereas the B is a small red dwarf. The pair has an angular separation of 16.2″.[4]


  1. ^ a b Johnson, H. M. & Wright, C. D. (183). "Predicted infrared brightness of stars within 25 parsecs of the sun". Astrophysical Journal Supplement Series 53 (2): 643–711. Bibcode:1983ApJS...53..643J. doi:10.1086/190905. 
  2. ^ a b c Flynn, C.; Morell, O. (1997). "Metallicities and kinematics of G and K dwarfs". Monthly Notices of the Royal Astronomical Society 286 (2): 617–625. arXiv:astro-ph/9609017. doi:10.1093/mnras/286.3.617. 
  3. ^ Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". The Astrophysical Journal 687 (2): 1264–1293. arXiv:0807.1686. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785. 
  4. ^ Poveda, A.; Herrera, M. A.; Allen, C.; Cordero, G.; Lavalley, C. (1994). "The new astrometry". Revista Mexicana de Astronomia y Astrofisica 28: 43–89. Bibcode:1994RMxAA..28...43P. 

External links[edit]