HR 4458

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HR 4458
Observation data
Epoch J2000      Equinox J2000
Constellation Hydra
Right ascension 11h 34m 29.487s[1]
Declination –32° 49′ 52.82″[1]
Apparent magnitude (V) 5.97[2]/15
Spectral type K0 V[3] + DC8[4]
U−B color index 0.325[2]
B−V color index 0.80[2]
V−R color index 0.44
R−I color index 0.40
Radial velocity (Rv) –22.21[5] km/s
Proper motion (μ) RA: –671.54[6] mas/yr
Dec.: 823.85[6] mas/yr
Parallax (π) 104.61 ± 0.37[6] mas
Distance 31.2 ± 0.1 ly
(9.56 ± 0.03 pc)
Absolute magnitude (MV) 6.05[7]
HR 4458 A
Mass 0.87[citation needed] M
Radius 0.84[8] R
Luminosity (bolometric) 0.368[9] L
Surface gravity (log g) 4.59[10] cgs
Temperature 5,241[10] K
Metallicity [Fe/H] –0.37[10] dex
Rotational velocity (v sin i) 6.79[11] km/s
Age 4.6–5.8[12] Gyr
Other designations
289 G. Hydrae, CD -32°8179, GCTP 2678.00, GJ 432, HD 100623, HIP 56452, LHS 308, LTT 4280, SAO 202583.
WD 1132-325: VB 04
Database references

HR 4458 (289 G. Hydrae) is a binary star system in the constellation Hydra. At a distance of 31 light years, it is the closest star system to the solar system within this constellation. The primary is K-type main-sequence star of class K0. It has a common proper motion companion at an angular separation of 16.2″. This is a white dwarf star with a classification of DC8.[4]

The primary has been examined for the presence of an infrared excess, but none was detected.[9]


  1. ^ a b Zacharias, N.; et al. (2013). "The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)". The Astronomical Journal. 145 (2). 44. Bibcode:2013AJ....145...44Z. arXiv:1212.6182Freely accessible. doi:10.1088/0004-6256/145/2/44. Vizier catalog entry
  2. ^ a b c Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV data. Bibcode:1986EgUBV........0M. 
  3. ^ Gray, R. O.; et al. (2006). "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132 (1): 161–70. Bibcode:2006AJ....132..161G. arXiv:astro-ph/0603770Freely accessible. doi:10.1086/504637. 
  4. ^ a b Holberg, J. B.; et al. (November 2013). "Where are all the Sirius-like binary systems?". Monthly Notices of the Royal Astronomical Society. 435 (3): 2077–2091. Bibcode:2013MNRAS.435.2077H. arXiv:1307.8047Freely accessible. doi:10.1093/mnras/stt1433. 
  5. ^ Nidever, David L.; et al. (August 2002). "Radial Velocities for 889 Late-Type Stars". The Astrophysical Journal Supplement Series. 141 (2): 503–522. Bibcode:2002ApJS..141..503N. arXiv:astro-ph/0112477Freely accessible. doi:10.1086/340570. 
  6. ^ a b c van Leeuwen, F. (2007). "Validation of the New Hipparcos Reduction". Astronomy and Astrophysics. 474 (2): 653–64. Bibcode:2007A&A...474..653V. arXiv:0708.1752Freely accessible. doi:10.1051/0004-6361:20078357. 
  7. ^ Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, Bibcode:2009A&A...501..941H, arXiv:0811.3982Freely accessible, doi:10.1051/0004-6361/200811191. 
  8. ^ 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. 
  9. ^ a b Eiroa, C.; et al. (July 2013). "DUst around NEarby Stars. The survey observational results". Astronomy & Astrophysics. 555: A11. Bibcode:2013A&A...555A..11E. arXiv:1305.0155Freely accessible. doi:10.1051/0004-6361/201321050. 
  10. ^ a b c Ramírez, I.; et al. (September 2012). "Lithium Abundances in nearby FGK Dwarf and Subgiant Stars: Internal Destruction, Galactic Chemical Evolution, and Exoplanets". The Astrophysical Journal. 756 (1): 46. Bibcode:2012ApJ...756...46R. arXiv:1207.0499Freely accessible. doi:10.1088/0004-637X/756/1/46. 
  11. ^ Martínez-Arnáiz, R.; et al. (September 2010). "Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter". Astronomy and Astrophysics. 520: A79. Bibcode:2010A&A...520A..79M. arXiv:1002.4391Freely accessible. doi:10.1051/0004-6361/200913725. 
  12. ^ 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. Bibcode:2008ApJ...687.1264M. arXiv:0807.1686Freely accessible. doi:10.1086/591785. 

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