21 Cancri

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21 Cancri
Observation data
Epoch J2000      Equinox J2000
Constellation Cancer
Right ascension 08h 23m 55.20938s[1]
Declination +10° 37′ 55.4040″[1]
Apparent magnitude (V) 6.08[2]
Characteristics
Evolutionary stage M2III[3]
B−V color index 1.507±0.004[4]
Variable type suspected[5]
Astrometry
Radial velocity (Rv)34.65[6] km/s
Proper motion (μ) RA: −0.730[6] mas/yr
Dec.: −23.274[6] mas/yr
Parallax (π)4.0080 ± 0.0989[6] mas
Distance810 ± 20 ly
(250 ± 6 pc)
Details
Radius53[6] R☉
Luminosity587[6] L☉
Temperature3,885[6] K
Other designations
NSV 17875, BD+11°1830, HD 70734, HIP 41163, HR 3290, SAO 97788
Database references
SIMBADdata

21 Cancri is a double star in the northern zodiac constellation of Cancer. It is just visible to the naked eye as a dim, red-hued star with an apparent visual magnitude of 6.08.[2] The star is located around 820 light years away from the Sun, based on parallax. It is moving further from the Earth with a heliocentric radial velocity of 35 km/s.[6]

The brighter component is an aging red giant with a stellar classification of M2III.[3] It is currently on the asymptotic giant branch, indicating this is a highly evolved star that has exhausted both its core hydrogen and core helium.[7] This is a suspected variable star.[5] It has expanded to 53[6] times the radius of the Sun and is radiating 587[6] times the Sun's luminosity from its swollen photosphere at an effective temperature of 3,885 K.[6] A 9th magnitude companion star is located one arc second away.[7]

References[]

  1. ^ a b van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  2. ^ a b Ducati, J. R. (2002). "VizieR On-line Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". VizieR On-line Data Catalog. Bibcode:2002yCat.2237....0D.
  3. ^ a b Abt, H. A. (1985). "Visual multiples. VIII. 1000 MK types". The Astrophysical Journal Supplement Series. 59: 95. Bibcode:1985ApJS...59...95A. doi:10.1086/191064.
  4. ^ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
  5. ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/GCVS. Bibcode:2009yCat....102025S.
  6. ^ a b c d e f g h i j k 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.
  7. ^ a b Eggen, Olin J. (1992). "Asymptotic Giant Branch Stars Near the Sun". The Astronomical Journal. 104: 275. Bibcode:1992AJ....104..275E. doi:10.1086/116239.
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