Astronomy:Xi1 Canis Majoris
  | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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[1] mas |
| 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 |
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.
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
- ↑ 1.0 1.1 1.2 1.3 1.4 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 "International Variable Star Index". https://www.aavso.org/vsx/index.php?view=detail.top&oid=5509.
- ↑ 3.0 3.1 3.2 Hubrig, S. et al. (January 2009). "New magnetic field measurements of beta Cephei stars and Slowly Pulsating B stars". Astronomische Nachrichten 330 (4): 317. doi:10.1002/asna.200811187. Bibcode: 2009AN....330..317H.
- ↑ 4.0 4.1 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). "Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30". in Batten, Alan Henry; Heard, John Frederick. 30. 57. Bibcode: 1967IAUS...30...57E.
- ↑ 6.00 6.01 6.02 6.03 6.04 6.05 6.06 6.07 6.08 6.09 6.10 6.11 6.12 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. doi:10.1093/mnras/stx1632. Bibcode: 2017MNRAS.471.2286S.
- ↑ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html.
- ↑ 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. doi:10.1093/mnrasl/sly070. Bibcode: 2018MNRAS.478L..39S.
- ↑ 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. doi:10.1086/323920. Bibcode: 2001AJ....122.3466M.
 |  |
