| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cancer |
| Right ascension | 08 43 12.32940 |
| Declination | +12° 40′ 51.1486″ |
| Apparent magnitude (V) | 5.62 |
| Characteristics | |
| Spectral type | G8 III and A3 III |
| B−V color index | 0.435±0.005 |
| Astrometry | |
| Radial velocity (Rv) | −6.2±2.3 km/s |
| Proper motion (μ) | RA: −9.828 mas/yr Dec.: +0.916 mas/yr |
| Parallax (π) | 4.7700 ± 0.1025 mas |
| Distance | 680 ± 10 ly (210 ± 5 pc) |
| Absolute magnitude (MV) | −1.62 |
| Orbit | |
| Period (P) | 1,009.36±0.12 d |
| Eccentricity (e) | 0.461±0.002 |
| Semi-amplitude (K1) (primary) | 20.04±0.06 km/s |
| Semi-amplitude (K2) (secondary) | 20.75±0.02 km/s |
| Details | |
| 45 Cnc A | |
| Mass | 3.11±0.10 M☉ |
| Radius | 13.86+5.03 −1.73 R☉ |
| Luminosity | 210.3±5.4 L☉ |
| Surface gravity (log g) | 2.72 cgs |
| Temperature | 5,058 K |
| Metallicity | −0.69±0.22 dex |
| Rotational velocity (v sin i) | 5.3 km/s |
| 45 Cnc B | |
| Mass | 3.00±0.10 M☉ |
| Luminosity | 190.5+43.9 −35.6 L☉ |
| Other designations | |
| A Cnc,[7], 45 Cnc, BD+13°1972, FK5 2686, HD 74228, HIP 42795, HR 3450, SAO 98069 | |
| Database references | |
| SIMBAD | data |
45 Cancri is a binary star system in the zodiac constellation of Cancer, located 680 light-years away from the Sun. It has the Bayer designation A Cancri; 45 Cancri is the Flamsteed designation. It is visible to the naked eye as a faint, white-hued star at an apparent visual magnitude of 5.62. The pair form a double-lined spectroscopic binary with an orbital period of 2.76 years and an eccentricity of 0.46. They are drifting closer to the Earth with a heliocentric radial velocity of −6 km/s.
The primary, designated component A, is an aging giant star with a stellar classification of G8 III, but has most likely not yet made multiple ascents up the red giant branch. It has 3.11 times the mass of the Sun and has expanded to 14 times the Sun's radius. The star is radiating 210 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 5,058 K. The less evolved secondary, component B is likewise a giant star, having a class of A3 III. It has three times the mass of the Sun and shines with 191 times the Sun's luminosity.
References
- ^ 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.
- ^ 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.
- ^ Griffin, R. E. M.; Griffin, R. F. (February 2015), "Composite spectra: XX. 45 Cancri. Two stars with very similar masses but quite different evolutionary states", Astronomische Nachrichten, 336 (2): 178–188, Bibcode:2015AN....336..178G, doi:10.1002/asna.201412148
- ^ Eggleton, Peter P.; Yakut, Kadri (July 2017), "Models for 60 double-lined binaries containing giants", Monthly Notices of the Royal Astronomical Society, 468 (3): 3533–3556, arXiv:1611.05041, Bibcode:2017MNRAS.468.3533E, doi:10.1093/mnras/stx598.
- ^ Soubiran, Caroline; et al. (2016), "The PASTEL catalogue: 2016 version", Astronomy & Astrophysics, 591: A118, arXiv:1605.07384, Bibcode:2016A&A...591A.118S, doi:10.1051/0004-6361/201628497, S2CID 119258214.
- Schröder, C.; Reiners, Ansgar; Schmitt, Jürgen H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo" (PDF), Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377
- ^ HD 74228, HD-DM-GC-HR-HIP-Bayer-Flamsteed Cross Index, N. D. Kostjuk, Institute of Astronomy of Russian Academy of Sciences, 2002; CDS ID IV/27A.
- "45 Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-03-04.
- Ginestet, N.; Carquillat, J. M. (2002), "Spectral Classification of the Hot Components of a Large Sample of Stars with Composite Spectra, and Implication for the Absolute Magnitudes of the Cool Supergiant Components", The Astrophysical Journal Supplement Series, 143 (2): 513, Bibcode:2002ApJS..143..513G, doi:10.1086/342942, S2CID 120976247
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