Astronomy:HR 4458

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Short description: Binary star system in the constellation Hydra
HR 4458
Location of 20 Crateris (circled in red)
Observation data
{{#ifeq:J2000|J2000.0 (ICRS)|Epoch J2000.0      Equinox J2000.0 (ICRS)| Epoch J2000      [[Astronomy:Equinox (celestial coordinates)|Equinox J2000}}
Constellation Hydra[1]
A
Right ascension  11h 34m 29.48644s[2]
Declination −32° 49′ 52.8228″[2]
Apparent magnitude (V) 5.97[3]
B
Right ascension  11h 34m 30.47776s[4]
Declination −32° 50′ 02.4048″[4]
Apparent magnitude (V) 15[5]
Characteristics
A
Evolutionary stage main sequence[2]
Spectral type K0 V[6]
U−B color index +0.325[3]
B−V color index +0.80[3]
B
Evolutionary stage white dwarf[5]
Spectral type DC8[7]
Astrometry
A
Radial velocity (Rv)−22.09±0.12[2] km/s
Proper motion (μ) RA: −670.230[2] mas/yr
Dec.: +822.399[2] mas/yr
Parallax (π)104.6133 ± 0.0277[2] mas
Distance31.177 ± 0.008 ly
(9.559 ± 0.003 pc)
Absolute magnitude (MV)6.05[8]
B
Proper motion (μ) RA: –701.802 mas/yr
Dec.: +828.928 mas/yr
Parallax (π)104.6570 ± 0.0267[4] mas
Distance31.164 ± 0.008 ly
(9.555 ± 0.002 pc)
Absolute magnitude (MV)15[9]
Orbit[10]
Period (P)1,400+600
−510 yr
Semi-major axis (a)142+38
−37 au
Eccentricity (e)0.28+0.57
−0.22
Inclination (i)83.4+2.1
−7.1°
Details
HR 4458 A
Mass0.900+0.044
−0.045[10] M☉
Radius0.84[11] R☉
Luminosity (bolometric)0.368[12] L☉
Surface gravity (log g)4.59[13] cgs
Temperature5,241[13] K
Metallicity [Fe/H]−0.37[13] dex
Rotational velocity (v sin i)6.79[14] km/s
Age4.6–5.8[15] Gyr
HR 4458 B
Mass0.554±0.022[10] M☉
Luminosity (bolometric)0.000088[16] L☉
Surface gravity (log g)8.12[17] cgs
Temperature5,000[18] K
Age5.69[18][lower-alpha 1] Gyr
Other designations
20 Crt, CD−32°8179, GJ 432, HD 100623, HIP 56452, HR 4458, SAO 202583, LHS 308, LTT 4280, PLX 2678.00[19]
B: VB 4, WD 1132−325
Database references
SIMBADA
B
ARICNSdata

HR 4458 (HD 100623) is a binary star system 31.18 light-years away in the equatorial constellation of Hydra. It has the Flamsteed designation 20 Crateris[20] and the Gould designation 289 G. Hydrae;[21] the former refers to the constellation Crater, since Flamsteed numbered the stars of Crater and the central portion of Hydra as a separate constellation from the other parts of Hydra.[20] This object is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 5.97.[3] It is moving closer to the Earth with a heliocentric radial velocity of −22 km/s.[22]

The primary component is a K-type main-sequence star with a stellar classification of K0 V.[6] It is around five billion years old[15] with 90% of the Sun's mass[10] and 84% of the Sun's radius.[11] The star is radiating 37% of the Sun's luminosity[12] from its photosphere at an effective temperature of 5,241 K.[13] It has been examined for the presence of an infrared excess, but none was detected.[12]

The secondary, designated VB 4, is a 15th-magnitude white dwarf of class DC8 sharing common proper motion with the primary.[7][23] The orbital period of the pair is of 1,400 years, albeit with large uncertainty.[10]

Notes

  1. ↑ Cooling age

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific 99 (617): 695. doi:10.1086/132034. Bibcode: 1987PASP...99..695R  Constellation record for this object at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 3.2 3.3 Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode: 1986EgUBV........0M. 
  4. ↑ 4.0 4.1 4.2 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  5. ↑ 5.0 5.1 Holberg, J. B.; Oswalt, Terry D.; Sion, E. M. (2002). "A Determination of the Local Density of White Dwarf Stars". The Astrophysical Journal 571 (1): 512–518. doi:10.1086/339842. Bibcode: 2002ApJ...571..512H. 
  6. ↑ 6.0 6.1 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. doi:10.1086/504637. Bibcode: 2006AJ....132..161G. 
  7. ↑ 7.0 7.1 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. doi:10.1093/mnras/stt1433. Bibcode: 2013MNRAS.435.2077H. 
  8. ↑ 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. doi:10.1051/0004-6361/200811191. Bibcode: 2009A&A...501..941H. 
  9. ↑ Reid, I. Neill; Hawley, Suzanne L.; Gizis, John E. (1995). "The Palomar/MSU Nearby-Star Spectroscopic Survey. I. The Northern M Dwarfs -Bandstrengths and Kinematics". The Astronomical Journal 110: 1838. doi:10.1086/117655. Bibcode: 1995AJ....110.1838R. 
  10. ↑ 10.0 10.1 10.2 10.3 10.4 An, Qier; Brandt, Timothy D.; Brandt, G. Mirek; Venner, Alexander (October 2025). "Orbits and Masses for 156 Companions from Combined Astrometry and Radial Velocities, and a Validation of Gaia Non-single-star Solutions" (in en). The Astrophysical Journal Supplement Series 280 (2): 61. doi:10.3847/1538-4365/adfa99. ISSN 0067-0049. Bibcode: 2025ApJS..280...61A. 
  11. ↑ 11.0 11.1 Johnson, H. M.; Wright, C. D. (1983). "Predicted infrared brightness of stars within 25 parsecs of the sun". Astrophysical Journal Supplement Series 53 (2): 643–711. doi:10.1086/190905. Bibcode: 1983ApJS...53..643J. 
  12. ↑ 12.0 12.1 12.2 Eiroa, C. et al. (July 2013). "DUst around NEarby Stars. The survey observational results". Astronomy & Astrophysics 555: A11. doi:10.1051/0004-6361/201321050. Bibcode: 2013A&A...555A..11E. 
  13. ↑ 13.0 13.1 13.2 13.3 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. doi:10.1088/0004-637X/756/1/46. Bibcode: 2012ApJ...756...46R. 
  14. ↑ 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. doi:10.1051/0004-6361/200913725. Bibcode: 2010A&A...520A..79M. 
  15. ↑ 15.0 15.1 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. doi:10.1086/591785. Bibcode: 2008ApJ...687.1264M. 
  16. ↑ Holberg, J. B.; Oswalt, T. D.; Sion, E. M.; McCook, G. P. (2016). "The 25 parsec local white dwarf population". Monthly Notices of the Royal Astronomical Society 462 (3): 2295. doi:10.1093/mnras/stw1357. Bibcode: 2016MNRAS.462.2295H. 
  17. ↑ Hollands, M. A.; Tremblay, P. -E.; Gänsicke, B. T.; Gentile-Fusillo, N. P.; Toonen, S. (2018). "The Gaia 20 pc white dwarf sample". Monthly Notices of the Royal Astronomical Society 480 (3): 3942. doi:10.1093/mnras/sty2057. Bibcode: 2018MNRAS.480.3942H. 
  18. ↑ 18.0 18.1 Bagnulo, S.; Landstreet, J. D. (2021). "New insight into the magnetism of degenerate stars from the analysis of a volume-limited sample of white dwarfs". Monthly Notices of the Royal Astronomical Society 507 (4): 5902. doi:10.1093/mnras/stab2046. Bibcode: 2021MNRAS.507.5902B. 
  19. ↑ "HD 100623". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+100623. 
  20. ↑ 20.0 20.1 Wagman, M. (August 1987). "Flamsteed's Missing Stars". Journal for the History of Astronomy 18 (3): 215. doi:10.1177/002182868701800305. Bibcode: 1987JHA....18..209W. 
  21. ↑ Gould, Benjamin Apthorp (1879). "Uranometria Argentina catalog of bright southern stars". Resultados del Observatorio Nacional Argentino en Cordoba (Buenos Aires) 1. Bibcode: 1879RNAO....1.....G. http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=V%2F135%2Fcatalog. Retrieved 2012-05-08. 
  22. ↑ Nidever, David L. et al. (August 2002). "Radial Velocities for 889 Late-Type Stars". The Astrophysical Journal Supplement Series 141 (2): 503–522. doi:10.1086/340570. Bibcode: 2002ApJS..141..503N. 
  23. ↑ Rodriguez, David R. et al. (2015). "Stellar multiplicity and debris discs: An unbiased sample". Monthly Notices of the Royal Astronomical Society 449 (3): 3160. doi:10.1093/mnras/stv483. Bibcode: 2015MNRAS.449.3160R. 



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