Astronomy:21 Cancri
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Cancer |
| Right ascension | 08h 23m 55.20829s[1] |
| Declination | +10° 37′ 55.4169″[1] |
| Apparent magnitude (V) | 6.08[2] |
| Characteristics | |
| Spectral type | M2III[3] |
| B−V color index | 1.507±0.004[4] |
| Variable type | suspected[5] |
| Astrometry | |
| Radial velocity (Rv) | 4.53[1] km/s |
| Proper motion (μ) | RA: −0.843[1] mas/yr Dec.: −22.943[1] mas/yr |
| Parallax (π) | 4.1258 ± 0.0272[1] mas |
| Distance | 791 ± 5 ly (242 ± 2 pc) |
| Details | |
| Radius | 53[6] R☉ |
| Luminosity | 587[6] L☉ |
| Temperature | 3,885[6] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
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 791 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
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 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.
- ↑ 2.0 2.1 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.
- ↑ 3.0 3.1 Abt, H. A. (1985). "Visual multiples. VIII. 1000 MK types". The Astrophysical Journal Supplement Series 59: 95. doi:10.1086/191064. Bibcode: 1985ApJS...59...95A.
- ↑ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ 5.0 5.1 Samus, N. N. 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.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 7.0 7.1 Eggen, Olin J. (1992). "Asymptotic Giant Branch Stars Near the Sun". The Astronomical Journal 104: 275. doi:10.1086/116239. Bibcode: 1992AJ....104..275E.
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