Xi1 Canis Majoris

ξ¹ Canis Majoris
	Location of ξ1 Canis Majoris (circled)
Observation data; Epoch J2000.0 Equinox J2000.0
Constellation	Canis Major
Right ascension	06h 31m 51.36636s
Declination	−23° 25′ 06.3181″
Apparent magnitude (V)	4.33 – 4.36
Characteristics
Spectral type	B1 III
U−B color index	−0.98
B−V color index	−0.24
Variable type	β Cep
Astrometry
Radial velocity (Rv)	+26.9 km/s
Proper motion (μ)	RA: −2.91 mas/yr ; Dec.: +6.22 mas/yr
Parallax (π)	2.36 ± 0.20 mas
Distance	1,400 ± 100 ly ; (420 ± 40 pc)
Absolute magnitude (MV)	−3.86
Details
Mass	14.2±0.4 M☉
Radius	7.9±0.6 R☉
Luminosity	30,900+8,900; −6,900 L☉
Surface gravity (log g)	3.78±0.07 cgs
Temperature	27,000±1,000 K
Metallicity [Fe/H]	−0.18 dex
Rotational velocity (v sin i)	0 km/s
Age	11.1±0.7 Myr
Other designations
	ξ1 CMa, 4 Canis Majoris, CD−23°3991, GC 8496, HD 46328, HIP 31125, HR 2387, SAO 171895, ADS 5176, CCDM 06319-2325
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]

A light curve for Xi¹ Canis Majoris, plotted from *TESS* data^[8]

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

^ ^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.

[vanLeeuwen2007-1] 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.

[vsx-2] "International Variable Star Index". Retrieved 2018-11-13.

[an330_4_317-3] 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.

[Johnson1966-4] 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.

[rgcrv-5] 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.

[schultz2017-6] ^ ^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.

[Anderson2012-7] 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-8] "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 20 August 2022.

[schultz2018-9] 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.

[wds-10] 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.

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Xi1 Canis Majoris

References

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