Binary star system in the constellation Hydra
HR 4458 Location of 20 Crateris (circled in red)
Observation dataEpoch J2000 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−Bcolor index +0.325[ 3] B−Vcolor index +0.80[ 3] B Evolutionary stage white dwarf [ 5] Spectral type DC8[ 7] Astrometry A Radial velocity (Rv )± 0.12[ 2] km/s Proper motion (μ)RA: –670.230mas /yr [ 2] Dec.: +822.399mas /yr [ 2] Parallax (π)104.6133± 0.0277 mas [ 2] Distance 31.177 ± 0.008 ly pc ) Absolute magnitude (MV )6.05[ 8] B Proper motion (μ)RA: –701.802mas /yr [ 4] Dec.: +828.928mas /yr [ 4] Parallax (π)104.6570± 0.0267 mas [ 4] Distance 31.164 ± 0.008 ly pc ) Absolute magnitude (MV )15[ 9] Details HR 4458 A Mass 0.87[ 2] M ☉ Radius 0.84[ 10] R ☉ Luminosity (bolometric) 0.368[ 11] L ☉ Surface gravity (log g )4.59[ 12] cgs Temperature 5,241[ 12] K Metallicity [Fe/H] −0.37[ 12] dex Rotational velocity (v sin i )6.79[ 13] Age 4.6–5.8[ 14] Gyr HR 4458 B Mass 0.58[ 15] M ☉ Luminosity (bolometric) 0.000088[ 16] L ☉ Surface gravity (log g )8.12[ 17] cgs Temperature 5,000[ 15] K Age 5.69[ 15] [ a] Gyr Other designations 20 Crt ,289 G. Hya ,CD −32°8179GJ 432HD 100623HIP 56452HR 4458SAO 202583LHS 308LTT 4280PLX 2678.00[ 18] B :VB 4,WD 1132−325Database references SIMBAD A B ARICNS data
HR 4458 (HD 100623 ) is abinary star system 31.18 light-years away in theequatorial constellation ofHydra . It has theFlamsteed designation 20 Crateris [ 19] Gould designation 289 G. Hydrae ;[ 20] Crater , since Flamsteed numbered the stars of Crater and the central portion of Hydra as a separate constellation from the other parts of Hydra.[ 19] apparent visual magnitude of 5.97.[ 3] radial velocity of −22 km/s.[ 21]
The primary component is aK-type main-sequence star with astellar classification of K0 V.[ 6] [ 14] Sun's radius .[ 10] Sun's luminosity [ 11] photosphere at aneffective temperature of 5,241 K.[ 12] infrared excess , but none was detected.[ 11]
There is a 15th-magnitudecommon proper motion companion called VB4 at anangular separation of″ [ 7] projected separation ofAU [ 22] white dwarf star with a classification of DC8.[ 7] [ 22]
^ Roman, Nancy G. (1987)."Identification of a constellation from a position" .Publications of the Astronomical Society of the Pacific 99 (617): 695.Bibcode :1987PASP...99..695R .doi :10.1086/132034 Constellation record for this object atVizieR .^a b c d e f g Vallenari, A.; et al. (Gaia collaboration) (2023)."Gaia Data Release 3. Summary of the content and survey properties" .Astronomy and Astrophysics .674 : A1.arXiv :2208.00211 Bibcode :2023A&A...674A...1G .doi :10.1051/0004-6361/202243940 S2CID 244398875 . Gaia DR3 record for this source atVizieR .^a b c d Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)".Catalogue of Eggen's UBV Data .Bibcode :1986EgUBV........0M . ^a b c d Vallenari, A.; et al. (Gaia collaboration) (2023)."Gaia Data Release 3. Summary of the content and survey properties" .Astronomy and Astrophysics .674 : A1.arXiv :2208.00211 Bibcode :2023A&A...674A...1G .doi :10.1051/0004-6361/202243940 S2CID 244398875 . Gaia DR3 record for this source atVizieR .^a b 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.arXiv :astro-ph/0102120 Bibcode :2002ApJ...571..512H .doi :10.1086/339842 ^a b 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 . ^a b c 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 ^ 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 . ^ 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.Bibcode :1995AJ....110.1838R .doi :10.1086/117655 . ^a b 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.Bibcode :1983ApJS...53..643J .doi :10.1086/190905 ^a b c 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 . ^a b c d 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 . ^ 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.arXiv :1002.4391 Bibcode :2010A&A...520A..79M .doi :10.1051/0004-6361/200913725 .S2CID 43455849 . ^a b 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 . ^a b c 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.arXiv :2106.11109 Bibcode :2021MNRAS.507.5902B .doi :10.1093/mnras/stab2046 ^ 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.arXiv :1606.01236 Bibcode :2016MNRAS.462.2295H .doi :10.1093/mnras/stw1357 ^ 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.arXiv :1805.12590 Bibcode :2018MNRAS.480.3942H .doi :10.1093/mnras/sty2057 ^ "HD 100623" .SIMBAD Centre de données astronomiques de Strasbourg . RetrievedMay 6, 2019 .^a b Wagman, M. (August 1987). "Flamsteed's Missing Stars".Journal for the History of Astronomy .18 (3): 215.Bibcode :1987JHA....18..209W .doi :10.1177/002182868701800305 .S2CID 118445625 . ^ Gould, Benjamin Apthorp (1879)."Uranometria Argentina catalog of bright southern stars" .Resultados del Observatorio Nacional Argentino en Cordoba .1 . Buenos Aires.Bibcode :1879RNAO....1.....G . Retrieved2012-05-08 . ^ 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 . ^a b 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
