| absmag_v = −3.86[12]
}}{{Starbox detail
| mass = {{val|14.2|0.4}}[12]
| gravity = {{val|3.78|0.07}}[12]
| rotational_velocity = 0[12]
| radius = {{val|7.9|0.6}}[12]
| luminosity = {{val|30,900|8,900|6,900}}[12]
| temperature = {{val|27,000|1,000}}[12]
| metal_fe = −0.18[19]
| age_myr = {{val|11.1|0.7}}[12]
}}{{Starbox catalog
| names={{odlist | B=ξ1 CMa | F=4 Canis Majoris | CD=−23°3991 | FK5= | HD=46328 | HIP=31125 | HR=2387 | SAO=171895 | ADS=5176 | CCDM=06319-2325 | GC=8496 }}
}}{{Starbox reference
|Simbad=ksi01+CMa
}}{{Starbox end}}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[4] or B0.5IV.[12] 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.[12]
The apparent magnitude varies from +4.33 to +4.36 with a period of 5.03 hours.[3] Its pulsations cause its radius to vary by 1.0% to 1.5%. At the same time its effective temperature by about {{val|500|ul=K}} above and below its mean temperature.[12]
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.[26] 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.[12]
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 {{val|27|ul="}} away.[28] 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.[12]
References
1. ^1 {{cite journal | title=XHIP: An extended hipparcos compilation | last1=Anderson | first1=E. | last2=Francis | first2=Ch. | journal=Astronomy Letters | volume=38 | issue=5 | pages=331 | year=2012 | bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015 | arxiv=1108.4971 }}
2. ^1 {{cite conference | last=Evans | first=D. S. | date=June 20–24, 1966 | editor1-last=Batten | editor1-first=Alan Henry | editor2-last=Heard | editor2-first=John Frederick | contribution=The Revision of the General Catalogue of Radial Velocities | title=Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30 | journal=Determination of Radial Velocities and Their Applications | volume=30 | pages=57 | bibcode=1967IAUS...30...57E }}
3. ^1 2 {{cite journal | display-authors=1 | last1=Johnson | first1=H. L. | last2=Iriarte | first2=B. | last3=Mitchell | first3=R. I. | last4=Wisniewskj | first4=W. Z. | title=UBVRIJKL photometry of the bright stars | journal=Communications of the Lunar and Planetary Laboratory | volume=4 | issue=99 | pages=99 | year=1966 | bibcode=1966CoLPL...4...99J }}
4. ^1 2 3 {{cite journal| display-authors=1 | last1=Hubrig | first1=S. | last2=Briquet | first2=M. | last3=De Cat | first3=P. | last4=Schoeller | first4=M. | last5=Morel | first5=T. | last6=Ilyin | first6=I. | title=New magnetic field measurements of beta Cephei stars and Slowly Pulsating B stars | journal=Astronomische Nachrichten | volume=330 | issue=4 | page=317 |date=January 2009 | bibcode=2009AN....330..317H | arxiv=0902.1314 | doi=10.1002/asna.200811187 }}
5. ^1 2 {{cite web|url=https://www.aavso.org/vsx/index.php?view=detail.top&oid=5509|title=International Variable Star Index|accessdate=2018-11-13}}
6. ^1 2 3 4 5 6 7 8 9 10 11 12 13 {{cite journal|bibcode=2017MNRAS.471.2286S|title=The pulsating magnetosphere of the extremely slowly rotating magnetic β Cep star ξ1 CMa|journal=Monthly Notices of the Royal Astronomical Society|volume=471|issue=2|pages=2286|last1=Shultz|first1=M.|last2=Wade|first2=G. A.|last3=Rivinius|first3=Th.|last4=Neiner|first4=C.|last5=Henrichs|first5=H.|last6=Marcolino|first6=W.|author7=MiMeS Collaboration|year=2017}}
7. ^1 {{cite journal|bibcode=2018MNRAS.478L..39S|title=The pulsationally modulated radial crossover signature of the slowly rotating magnetic B-type star ξ1 CMa|journal=Monthly Notices of the Royal Astronomical Society|volume=478|issue=1|pages=L39|last1=Shultz|first1=M.|last2=Kochukhov|first2=O.|last3=Wade|first3=G. A.|last4=Rivinius|first4=Th|year=2018}}
8. ^1 {{cite journal|bibcode=2001AJ....122.3466M|title=The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog|journal=The Astronomical Journal|volume=122|issue=6|pages=3466|last1=Mason|first1=Brian D.|last2=Wycoff|first2=Gary L.|last3=Hartkopf|first3=William I.|last4=Douglass|first4=Geoffrey G.|last5=Worley|first5=Charles E.|year=2001}}