HR 4458

HR 4458 is a binary star system in the equatorial constellation of Hydra. It has the Gould designation 289 G. Hydrae; HR 4458 is the Bright Star Catalogue designation. At a distance of 31.13 light years, it is the closest star system to the Solar System within this constellation. This object is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 5.97.[2] It is moving closer to the Earth with a heliocentric radial velocity of −22 km/s.[5]

HR 4458
Observation data
Epoch J2000      Equinox J2000
Constellation Hydra
Right ascension 11h 34m 29.48628s[1]
Declination –32° 49′ 52.8199″[1]
Apparent magnitude (V) 5.97[2] + 15
Characteristics
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
Astrometry
Radial velocity (Rv)–22.21[5] km/s
Proper motion (μ) RA: –670.120[1] mas/yr
Dec.: +822.228[1] mas/yr
Parallax (π)104.7828 ± 0.0518 mas[1]
Distance31.13 ± 0.02 ly
(9.544 ± 0.005 pc)
Absolute magnitude (MV)6.05[6]
Details
HR 4458 A
Radius0.84[7] R☉
Luminosity (bolometric)0.368[8] L☉
Surface gravity (log g)4.59[9] cgs
Temperature5,241[9] K
Metallicity [Fe/H]–0.37[9] dex
Rotational velocity (v sin i)6.79[10] km/s
Age4.6–5.8[11] Gyr
Other designations
289 G. Hydrae, CD−32°8179, GJ 432, HD 100623, HIP 56452, HR 4458, SAO 202583, LHS 308, LTT 4280[12]
WD 1132-325: VB 04
Database references
SIMBADdata
ARICNSdata

The primary component is K-type main-sequence star with a stellar classification of K0 V.[3] It is around five[11] billion years old with 84%[7] of the Sun's radius. The star is radiating 37%[8] of the Sun's luminosity from its photosphere at an effective temperature of 5,241 K.[9] It has been examined for the presence of an infrared excess, but none was detected.[8]

There is a common proper motion companion at an angular separation of 16.2″,[4] corresponding to a projected separation of 162.5 AU.[13] This is a white dwarf star with a classification of DC8.[4] The orbital period of the pair is estimated as 1,110 years.[13]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 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 "Compilation of Eggen's UBV data, transformed to UBV (unpublished)".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. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637. S2CID 119476992.
  4. 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. arXiv:1307.8047. Bibcode:2013MNRAS.435.2077H. 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. arXiv:astro-ph/0112477. Bibcode:2002ApJS..141..503N. doi:10.1086/340570. S2CID 51814894.
  6. 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, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191, S2CID 118577511.
  7. 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.
  8. Eiroa, C.; et al. (July 2013). "DUst around NEarby Stars. The survey observational results". Astronomy & Astrophysics. 555: A11. arXiv:1305.0155. Bibcode:2013A&A...555A..11E. doi:10.1051/0004-6361/201321050. S2CID 377244.
  9. 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. arXiv:1207.0499. Bibcode:2012ApJ...756...46R. doi:10.1088/0004-637X/756/1/46. S2CID 119199829.
  10. 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" (PDF). Astronomy and Astrophysics. 520: A79. arXiv:1002.4391. Bibcode:2010A&A...520A..79M. doi:10.1051/0004-6361/200913725. S2CID 43455849. Archived from the original (PDF) on 2017-09-22. Retrieved 2018-11-04.
  11. 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. S2CID 27151456.
  12. "HD 100623". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 6, 2019.
  13. Rodriguez, David R.; et al. (2015). "Stellar multiplicity and debris discs: An unbiased sample". Monthly Notices of the Royal Astronomical Society. 449 (3): 3160. arXiv:1503.01320. Bibcode:2015MNRAS.449.3160R. doi:10.1093/mnras/stv483.
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