R Canis Majoris

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R Canis Majoris
Canis Major constellation map.svg
Red circle.svg
Location of R CMa (circled)
Observation data
Epoch J2000.0        Equinox
Constellation Canis Major
Right ascension 07h 19m 28.18202s [1]
Declination −16° 23′ 42.8773″ [1]
Apparent magnitude  (V)5.70 - 6.34 [2]
Characteristics
Spectral type F0V + G8IV [3]
U−B color index +0.01 [3]
B−V color index +0.34 [3]
Variable type Algol
Astrometry
Radial velocity (Rv)−39.0 [4] km/s
Proper motion (μ)RA: +165.37 [1] mas/yr
Dec.: −136.18 [1] mas/yr
Parallax (π)23.38±0.54  mas [1]
Distance 44 [3]   pc
Absolute magnitude  (MV)+2.57 [5]
Details [3]
primary
Mass 1.67  M☉
Radius 1.78  R☉
Luminosity 8.2  L☉
Surface gravity (log g)4.16  cgs
Temperature 7,300  K
Rotational velocity (v sin i)78.3±3.9 [5]  km/s
secondary
Mass 0.22  M☉
Radius 1.22  R☉
Luminosity 0.49  L☉
Surface gravity (log g)3.60  cgs
Temperature 4,350  K
tertiary
Mass 0.8  M☉
Radius 0.83  R☉
Luminosity 0.4  L☉
Surface gravity (log g)4.50  cgs
Other designations
R  Canis Majoris, BD−16°1898, HR  2788, HD  57167, HIP  35487, SAO  152724, GC  9758
Database references
SIMBAD data

R Canis Majoris is an eclipsing interacting binary star system in the constellation Canis Major. It varies from magnitude 5.7 to 6.34. [6] The system is unusual in the low ratio between the main two components and shortness of the orbital period. [3] It is faintly visible to the naked eye of an observer with very good observing conditions.

Contents

Variability

A visual band light curve for R Canis Majoris, adapted from Shobbrook (2005) RCMaLightCurve.png
A visual band light curve for R Canis Majoris, adapted from Shobbrook (2005)

In 1887, Edwin F. Sawyer discovered that the star, then generally referred to as 155 Canis Majoris (after its listing in Uranometria Argentina), is a variable star. [8] It appears with its variable star designation. R Canis Majoris, in Annie Jump Cannon's Second catalogue of variable stars, published in 1907. [9] Eclipse timings for R Canis Majoris have been being measured since 1887, and whilst at present the time period appears constant at 1.1359 days, periodic quasi-sinusoidal variations of the eclipse arrival times have been taking place with a periodicity of around 93 years. This has led to the suggestion that there exists a third non-eclipsing body in the system whose gravitational pull is responsible for these variations. [10]

Interacting binary star

R Canis Majoris is thought to be an interacting binary star. The secondary star, originally the more massive of the two, has evolved away from the main sequence, expanded, and exceeded its Roche lobe. The primary has stripped away mass from the secondary, with much of it being lost completely from the system. The secondary now has a very reduced mass relative to its temperature and luminosity, while the primary has gained helium-rich material and become hotter and more luminous. [11]

Reanalysis of the system using high-resolution spectroscopy yields its two main components to have masses 1.67±0.08 and 0.22±0.07 times that of the Sun respectively and radii 1.78±0.03 and 1.22±0.07 times that of the Sun respectively. Their surface temperatures are 7,300  K and 4,350 K. A third star in the system is very faint, presumed to be an orange dwarf. A tentative orbit has been derived with a period of 102 years. The third star has a mass 80% that of the Sun and a radius around 83% that of the Sun. [3]

References

  1. 1 2 3 4 5 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.
  2. ↑ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  3. 1 2 3 4 5 6 7 Budding, E.; Butland, R. (2011). "Observations and analysis of the system R Canis Majoris". Monthly Notices of the Royal Astronomical Society . 418 (3): 1764–73. Bibcode:2011MNRAS.418.1764B. doi: 10.1111/j.1365-2966.2011.19597.x .
  4. ↑ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
  5. 1 2 Ammler-von Eiff, Matthias; Reiners, Ansgar (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics, 542: A116, arXiv: 1204.2459 , Bibcode:2012A&A...542A.116A, doi:10.1051/0004-6361/201118724, S2CID   53666672.
  6. ↑ Watson, Christopher (4 January 2010). "R Canis Majoris". AAVSO Website. American Association of Variable Star Observers . Retrieved 18 February 2014.
  7. ↑ Shobbrook, R. R. (December 2005). "Photometry of 20 eclipsing and ellipsoidal binary systems". The Journal of Astronomical Data. 11: 7. Bibcode:2005JAD....11....7S . Retrieved 15 November 2021.
  8. ↑ Sawyer, Edwin F. (July 1887). "On a new variable of the Algol-type". Astronomical Journal. 7: 119–120. Bibcode:1887AJ......7..119S. doi:10.1086/100933 . Retrieved 1 January 2025.
  9. ↑ Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory. 55: 1–94. Bibcode:1907AnHar..55....1C . Retrieved 1 January 2025.
  10. ↑ Ribas, Ignasi; Arenou, Frédéric; Guinan, Edward F. (2002). "Astrometric and Light-Travel Time Orbits to Detect Low-Mass Companions: A Case Study of the Eclipsing System R Canis Majoris". The Astronomical Journal. 123 (4): 2033. arXiv: astro-ph/0201148 . Bibcode:2002AJ....123.2033R. doi:10.1086/339560.
  11. ↑ Varricatt, Watson P.; Ashok, N. M. (1999). "Near-Infrared Photometric Studies of R Canis Majoris". The Astronomical Journal. 117 (6): 2980. Bibcode:1999AJ....117.2980V. doi:10.1086/300870.
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