Xi1 Canis Majoris, Latinized from ξ1 Canis Majoris, is a Beta Cephei variable star in the constellation Canis Major. It is approximately 1,400 light years from Earth.
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 06h 31m 51.36636s[1] |
| Declination | −23° 25′ 06.3181″[1] |
| Apparent magnitude (V) | 4.33 – 4.36[2] |
| Characteristics | |
| Spectral type | B1 III[3] |
| U−B color index | −0.98[4] |
| B−V color index | −0.24[4] |
| Variable type | β Cep[3] |
| Astrometry | |
| Radial velocity (Rv) | +26.9[5] km/s |
| Proper motion (μ) | RA: −2.91[1] mas/yr Dec.: +6.22[1] mas/yr |
| Parallax (π) | 2.36 ± 0.20 mas[1] |
| Distance | 1,400 ± 100 ly (420 ± 40 pc) |
| Absolute magnitude (MV) | −3.86[6] |
| Details | |
| Mass | 14.2±0.4[6] M☉ |
| Radius | 7.9±0.6[6] R☉ |
| Luminosity | 30,900+8,900 −6,900[6] L☉ |
| Surface gravity (log g) | 3.78±0.07[6] cgs |
| Temperature | 27,000±1,000[6] K |
| Metallicity [Fe/H] | −0.18[7] dex |
| Rotational velocity (v sin i) | 0[6] km/s |
| Age | 11.1±0.7[6] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
ξ1 Canis Majoris is a blue-white B-type star. It has generally been assigned a luminosity class of III (giant) or IV (subgiant), for example B1III[3] or B0.5IV.[6] Comparison of its properties with model evolutionary tracks suggest that it is a main sequence star about three quarters of the way through its main sequence lifetime.[6]
The apparent magnitude varies from +4.33 to +4.36 with a period of 5.03 hours.[2] Its pulsations cause its radius to vary by 1.0% to 1.5%. At the same time its effective temperature by about 500 K above and below its mean temperature.[6]
ξ1 Canis Majoris has the longest known rotation period of any B class star, taking around 30 years to complete one revolution on its axis.[9] This is thought to be due to magnetic braking; ξ1 Canis Majoris has the strongest magnetic field of any β Cephei star and would be expected to spin down completely in around four million years. It also has the strongest and hardest X-ray emission of any β Cephei star.[6]
ξ1 Canis Majoris forms a naked eye pairing with ξ2 Canis Majoris a little less than a degree away. The Washington Double Star Catalog lists two 14th magnitude companions about 27″ away.[10] In addition, an unseen close companion is suspected due to some faint emission lines in the spectrum that are best explained by a Be star invisible against the brighter primary.[6]
References
edit- ^ a b c d e 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.
- ^ a b "International Variable Star Index". Retrieved 2018-11-13.
- ^ a b c Hubrig, S.; et al. (January 2009). "New magnetic field measurements of beta Cephei stars and Slowly Pulsating B stars". Astronomische Nachrichten. 330 (4): 317. arXiv:0902.1314. Bibcode:2009AN....330..317H. doi:10.1002/asna.200811187. S2CID 17497112.
- ^ a b Johnson, H. L.; et al. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99): 99. Bibcode:1966CoLPL...4...99J.
- ^ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick (eds.). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. Determination of Radial Velocities and Their Applications. Vol. 30. p. 57. Bibcode:1967IAUS...30...57E.
- ^ a b c d e f g h i j k l m Shultz, M.; Wade, G. A.; Rivinius, Th.; Neiner, C.; Henrichs, H.; Marcolino, W.; MiMeS Collaboration (2017). "The pulsating magnetosphere of the extremely slowly rotating magnetic β Cep star ξ1 CMa". Monthly Notices of the Royal Astronomical Society. 471 (2): 2286. arXiv:1706.08820. Bibcode:2017MNRAS.471.2286S. doi:10.1093/mnras/stx1632.
- ^ 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.
- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 20 August 2022.
- ^ Shultz, M.; Kochukhov, O.; Wade, G. A.; Rivinius, Th (2018). "The pulsationally modulated radial crossover signature of the slowly rotating magnetic B-type star ξ1 CMa". Monthly Notices of the Royal Astronomical Society. 478 (1): L39. arXiv:1804.07535. Bibcode:2018MNRAS.478L..39S. doi:10.1093/mnrasl/sly070.
- ^ Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.