45 Cancri is a binary star[4] system in the zodiac constellation of Cancer, located 680 light-years away from the Sun.[1] It has the Bayer designation A1 Cancri;[7] 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.[2] The pair form a double-lined spectroscopic binary with an orbital period of 2.76 years and an eccentricity of 0.46.[4] They are drifting closer to the Earth with a heliocentric radial velocity of −6 km/s.[2]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cancer |
| Right ascension | 08h 43m 12.32940s[1] |
| Declination | +12° 40′ 51.1486″[1] |
| Apparent magnitude (V) | 5.62[2] |
| Characteristics | |
| Spectral type | G8 III and A3 III[3] |
| B−V color index | 0.435±0.005[2] |
| Astrometry | |
| Radial velocity (Rv) | −6.2±2.3[2] km/s |
| Proper motion (μ) | RA: −9.828[1] mas/yr Dec.: +0.916[1] mas/yr |
| Parallax (π) | 4.7700 ± 0.1025 mas[1] |
| Distance | 680 ± 10 ly (210 ± 5 pc) |
| Absolute magnitude (MV) | −1.62[2] |
| Orbit[4] | |
| 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[3] M☉ |
| Radius | 13.86+5.03 −1.73[1] R☉ |
| Luminosity | 210.3±5.4[1] L☉ |
| Surface gravity (log g) | 2.72[5] cgs |
| Temperature | 5,058[5] K |
| Metallicity [Fe/H] | −0.69±0.22[5] dex |
| Rotational velocity (v sin i) | 5.3[6] km/s |
| 45 Cnc B | |
| Mass | 3.00±0.10[3] M☉ |
| Luminosity | 190.5+43.9 −35.6[3] L☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
The primary, designated component A, is an aging giant star with a stellar classification of G8 III,[9] but has most likely not yet made multiple ascents up the red giant branch.[3] It has 3.11[3] times the mass of the Sun and has expanded to 14[1] times the Sun's radius. The star is radiating 210[1] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 5,058 K.[5] 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.[3]
References
edit- ^ a b c d e f g h i j 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.
- ^ a b c d e f 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.
- ^ a b c d e f g 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
- ^ a b c 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.
- ^ a b c d 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[permanent dead link]
- ^ a b 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