NR Canis Majoris

NR Canis Majoris is a binary star[10] system in the southern constellation of Canis Major, located to the east of Sirius and Gamma Canis Majoris near the constellation border with Puppis. It has a yellow-white hue and is dimly visible to the naked eye with a combined apparent visual magnitude that fluctuates around 5.60.[2] It is located at a distance of approximately 297 light years from the Sun based on parallax.[1] The system is drifting closer to the Sun with a radial velocity of −29 km/s,[2] and in about three million years it is predicted to approach within 14.1+4.7
−4.0 ly.[11] At that time, the star will become the brightest in the night sky, potentially reaching magnitude −0.88.[12]

NR Canis Majoris
Observation data
Epoch J2000      Equinox J2000
Constellation Canis Major
Right ascension  07h 27m 07.99012s[1]
Declination −17° 51′ 53.5058″[1]
Apparent magnitude (V) 5.60[2] (5.66 + 9.23)[3]
Characteristics
Spectral type F2V[4]
B−V color index +0.314±0.002[2]
Variable type δ Sct[5]
Astrometry
Radial velocity (Rv)−29.2±2.9[2] km/s
Proper motion (μ) RA: −2.420[1] mas/yr
Dec.: +1.388[1] mas/yr
Parallax (π)10.9688 ± 0.0917[1] mas
Distance297 ± 2 ly
(91.2 ± 0.8 pc)
Absolute magnitude (MV)0.78[2]
Details
A
Mass1.62[6] or 2.18±0.04[7] M☉
Radius3.90+0.18
−0.24[1] R☉
Luminosity37.4±0.4[1] L☉
Surface gravity (log g)3.65[6] cgs
Temperature7,227+238
−160[1] K
Rotational velocity (v sin i)185[8] km/s
Age1.494[6] Gyr
Other designations
NR CMa, BD−17°1980, HD 58954, HIP 36186, HR 2853, SAO 152894, ADS 6093, CCDM J07271-1752AB, WDS J07271-1752[9]
Database references
SIMBADdata

The magnitude 5.66[3] primary component is an F-type main-sequence star with a stellar classification of F2V.[4] It is a Delta Scuti variable[5] that varies by a few hundredths of a magnitude over roughly 16 hours.[13] The star is an estimated 1.5 billion years old.[6] It has a high rate of spin with a projected rotational velocity of 185 km/s, which is giving the star an equatorial bulge that is estimated to be 8% larger than the polar radius.[8]

The secondary companion is magnitude 9.23 and lies at an angular separation of 1.3″ along a position angle of 39°, as of 2005.[3]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 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.
  3. Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. Retrieved 2015-07-22.
  4. Houk, Nancy; Smith-Moore, M. (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. 4. Ann Arbor: Department of Astronomy, University of Michigan. Bibcode:1988mcts.book.....H.
  5. Samus, N. N.; et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085.
  6. David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146.
  7. Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691.
  8. van Belle, Gerard T. (March 2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review. 20 (1): 51. arXiv:1204.2572. Bibcode:2012A&ARv..20...51V. doi:10.1007/s00159-012-0051-2.
  9. "NR CMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 12 February 2017.
  10. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x.
  11. Bailer-Jones, C. A. L. (March 2015). "Close encounters of the stellar kind". Astronomy & Astrophysics. 575: 13. arXiv:1412.3648. Bibcode:2015A&A...575A..35B. doi:10.1051/0004-6361/201425221. A35.
  12. Tomkin, Jocelyn (April 1998). "Once and Future Celestial Kings". Sky and Telescope. 95 (4): 59–63. Bibcode:1998S&T....95d..59T.
  13. Watson, Christopher (4 January 2010). "LS Canis Majoris". AAVSO Website. American Association of Variable Star Observers. Retrieved 12 July 2014.
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