15 Cancri
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cancer |
| Right ascension | 08h 13m 08.86806s[1] |
| Declination | +29° 39′ 23.5368″[1] |
| Apparent magnitude (V) | 5.53 - 5.65[2] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | A0:V:spSiSr[4] |
| B−V color index | −0.073±0.002[5] |
| Variable type | α2 CVn[2] |
| Astrometry | |
| Radial velocity (Rv) | 25.0±0.8[6] km/s |
| Proper motion (μ) | RA: −11.265[1] mas/yr Dec.: −19.506[1] mas/yr |
| Parallax (π) | 4.6720±0.2238 mas[1] |
| Distance | 700 ± 30 ly (210 ± 10 pc) |
| Absolute magnitude (MV) | −0.97[5] |
| Orbit[6] | |
| Primary | 15 Cancri A |
| Name | 15 Cancri B |
| Period (P) | 635.73±0.53 days[note 1] |
| Eccentricity (e) | 0.55±0.08 |
| Periastron epoch (T) | 2422045±18 |
| Argument of periastron (ω) (primary) | 196±13° |
| Semi-amplitude (K1) (primary) | 9.6±1.1 km/s |
| Details | |
| 15 Cnc A | |
| Mass | 2.4[3] M☉ |
| Radius | 3.4[3] R☉ |
| Luminosity | 131[3] L☉ |
| Surface gravity (log g) | 3.68[3] cgs |
| Temperature | 10,400[3] K |
| Rotation | 6.563 days[7] |
| Rotational velocity (v sin i) | 25[4] km/s |
| Age | 358[8] Gyr |
| Other designations | |
| 15 Cnc, BM Cnc, BD+30°1664, HD 68351, HIP 40240, HR 3215, GSC 01939-01462[9] | |
| Database references | |
| SIMBAD | data |
15 Cancri is an α2 CVn-type variable star in the zodiac constellation of Cancer, located around 700 light years away.[1] It has the variable star designation BM Cancri (BM Cnc); 15 Cancri (15 Cnc) is the Flamsteed designation. This system is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of about 5.6. It is moving away from the Earth with a heliocentric radial velocity of 25 km/s.[6]
Radial velocity measurements taken at the Dominion Astrophysical Observatory in Victoria, British Columbia Canada in 1918 and 1919 led to the determination that 15 Cancri is a single-lined spectroscopic binary system.[11] The first orbit was calculated in 1973 by Helmut Abt and Michael Snowden with a period of 585 days[12] however later measurements showed that the orbital period was 635 days.[6][note 1]
15 Cancri A, the visible component, is an Ap star, a chemically peculiar star with an over-abundance of iron peak elements, particularly silicon, chromium, and strontium, in its spectrum.[13][4]
Like all Ap stars, 15 Cancri has a strong magnetic field. This magnetic field varies as it rotates and in 1968 the visual brightness of the star was shown to vary regularly over about four days.[14] 15 Cancri was given the variable star designation BM Cancri in 1972 as a member of the α2 CVn class of variable stars.[15] The period has since been measured more accurately at 3.3095 d, believed to be the rotational period of the star.[16]
In Johann Bayer’s Uranometria, this star was designated as Psi Geminorum. When the constellation borders were set in 1930, it was moved to Cancer, so the designation has been dropped.[17]
Notes
References
- ^ a b c d e f 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 at VizieR.
- ^ 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. Bibcode:2009yCat....102025S.
- ^ a b c d e f Glagolevskij, Yu. V. (2019). "On Properties of Main Sequence Magnetic Stars". Astrophysical Bulletin. 74 (1): 66. Bibcode:2019AstBu..74...66G. doi:10.1134/S1990341319010073.
- ^ a b c Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". Astrophysical Journal Supplement. 99: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182.
- ^ a b 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 Stickland, D. J.; Weatherby, J. (1984). "Radial velocities of northern Mercury stars". Astronomy and Astrophysics Supplement Series. 57: 55–67. Bibcode:1984A&AS...57...55S.
- ^ Balona, L. A. (2022). "Rapidly oscillating TESS A-F main-sequence stars: Are the roAp stars a distinct class?". Monthly Notices of the Royal Astronomical Society. 510 (4): 5743. arXiv:2109.02246. Bibcode:2022MNRAS.510.5743B. doi:10.1093/mnras/stac011.
- ^ Kordopatis, G.; Schultheis, M.; McMillan, P. J.; Palicio, P. A.; De Laverny, P.; Recio-Blanco, A.; Creevey, O.; Álvarez, M. A.; Andrae, R.; Poggio, E.; Spitoni, E.; Contursi, G.; Zhao, H.; Oreshina-Slezak, I.; Ordenovic, C.; Bijaoui, A. (2023). "Stellar ages, masses, extinctions, and orbital parameters based on spectroscopic parameters of Gaia DR3". Astronomy and Astrophysics. 669: A104. arXiv:2206.07937. Bibcode:2023A&A...669A.104K. doi:10.1051/0004-6361/202244283.
- ^ "15 Cancri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2025-11-16.
- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
- ^ Plaskett, J. S.; et al. (1919). "Fourth list of spectroscopic binaries". Journal of the Royal Astronomical Society of Canada. 13: 372–378. Bibcode:1919JRASC..13..372P.
- ^ Abt, Helmut A.; Snowden, Michael S. (1973). "The Binary Frequency for AP Stars". Astrophysical Journal Supplement. 25: 137–162. Bibcode:1973ApJS...25..137A. doi:10.1086/190265.
- ^ Renson, P.; Manfroid, J. (2009). "Catalogue of Ap, Hg Mn and Am stars". Astronomy & Astrophysics. 498 (3): 961–966. Bibcode:2009A&A...498..961R. doi:10.1051/0004-6361/200810788.
- ^ Stepien, K. (1968). "Photometric behavior of magnetic stars". The Astrophysical Journal. 154: 945. Bibcode:1968ApJ...154..945S. doi:10.1086/149815.
- ^ Martins, D. H. (1972). "New Southern Variable Stars". Information Bulletin on Variable Stars. 705: 1. Bibcode:1972IBVS..705....1M.
- ^ Wraight, K. T.; Fossati, L.; Netopil, M.; Paunzen, E.; Rode-Paunzen, M.; Bewsher, D.; Norton, A. J.; White, Glenn J. (2012). "A photometric study of chemically peculiar stars with the STEREO satellites - I. Magnetic chemically peculiar stars★". Monthly Notices of the Royal Astronomical Society. 420 (1): 757–772. arXiv:1110.6283. Bibcode:2012MNRAS.420..757W. doi:10.1111/j.1365-2966.2011.20090.x. S2CID 14811051.
- ^ Ian Ridpath. "Bayer's Uranometria and Bayer letters". Retrieved 2017-11-27.