Beta Monocerotis

Beta Monocerotis (Beta Mon, β Monocerotis, β Mon) is a triple star system in the constellation of Monoceros.[1] To the naked eye, it appears as a single star with an apparent visual magnitude of approximately 3.74, making it the brightest visible star in the constellation.[2] A telescope shows a curved line of three pale blue stars (or pale yellow stars, depending on your scope's focus). The star system consists of three Be stars, β Monocerotis A, β Monocerotis B, and β Monocerotis C. There is also an additional visual companion star that is probably not physically close to the other three stars.[1]

Beta Monocerotis A

β Monocerotis A
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Monoceros
Right ascension 06h 28m 49.0700s[3]
Declination −07° 01′ 59.025″[3]
Apparent magnitude (V) 4.60[3]
Characteristics
Spectral type B3Ve[3]
U−B color index −0.63[2]
B−V color index −0.10[2]
R−I color index −0.16[2]
Astrometry
Radial velocity (Rv)20 ± 5[3] km/s
Proper motion (μ) RA: −7.00[3] mas/yr
Dec.: −4.97[3] mas/yr
Parallax (π)4.72 ± 1.10[3] mas
Distanceapprox. 700 ly
(approx. 210 pc)
Absolute magnitude (MV)−2.0[note 1]
Details
Mass7[1] M☉
Luminosity3,200[1] L☉
Rotational velocity (v sin i)346[2] km/s
Other designations
β Mon A, Beta Monocerotis A, Beta Mon A, β1 Monocerotis, β1 Mon, Beta1 Monocerotis, Beta1 Mon, 11 Monocerotis A, 11 Mon A, STF 919A, ADS 5107 A, BD−06°1574, CCDM J06288-0702A, GC 8412, HD 45725, HIP 30867,[note 2] HR 2356, SAO 133316, WDS 06288-0702A.[3][4]
Database references
SIMBADdata

Beta Monocerotis A (Beta Mon A, β Monocerotis A, β Mon A) is a Be star with a mass of approximately 7 solar masses and a luminosity of 3,200 times the Sun's.[1]

Beta Monocerotis B

β Monocerotis B
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Monoceros
Right ascension 06h 28m 49.424s[5]
Declination −07° 02′ 03.88″[5]
Apparent magnitude (V) 5.40[6]
Characteristics
Spectral type B3ne[6]
U−B color index −0.52[7]
B−V color index −0.07[7]
Astrometry
Radial velocity (Rv)18 ± 5[6] km/s
Proper motion (μ) RA: −7.00[5] mas/yr
Dec.: −4.97[5] mas/yr
Parallax (π)4.72 ± 1.10[5] mas
Distanceapprox. 700 ly
(approx. 210 pc)
Absolute magnitude (MV)−1[note 1]
Details
Mass6.2[1] M☉
Luminosity1,600[1] L☉
Rotational velocity (v sin i)123[7] km/s
Other designations
β Mon B, Beta Monocerotis B, Beta Mon B, 11 Monocerotis B, 11 Mon B, STF 919B, ADS 5107 B, BD−06°1575B, CCDM J06288-0702B, HD 45726, HIP 30867,[note 2] HR 2357, SAO 133317, WDS 06288-0702B.[3][4][6][8]
Database references
SIMBADdata

Beta Monocerotis B (Beta Mon B / β Monocerotis B / β Mon B) is a Be star with a mass of approximately 6.2 solar masses and a luminosity of 1,600 times the Sun's.[1]


Beta Monocerotis C

β Monocerotis C
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Monoceros
Right ascension 06h 28m 49.613s[9]
Declination −07° 02′ 04.76″[9]
Apparent magnitude (V) 5.60[10]
Characteristics
Spectral type B3e[10]
B−V color index −0.1[10]
Astrometry
Radial velocity (Rv)23 ± 5[10] km/s
Proper motion (μ) RA: −7.00[9] mas/yr
Dec.: −4.97[9] mas/yr
Parallax (π)4.72 ± 1.10[9] mas
Distanceapprox. 700 ly
(approx. 210 pc)
Absolute magnitude (MV)−1[note 1]
Details
Mass6[1] M☉
Luminosity1,300[1] L☉
Rotational velocity (v sin i)331[11] km/s
Other designations
β Mon C, Beta Monocerotis C, Beta Mon C, 11 Monocerotis C, 11 Mon C, STF 919C, ADS 5107 C, BD−06°1575C, CCDM J06288-0702C, HD 45727, HIP 30867,[note 2] HR 2358, WDS 06288-0702C.[10][4]
Database references
SIMBADdata

Beta Monocerotis C (Beta Mon C / β Monocerotis C / β Mon C) is a Be star with a mass of approximately 6 solar masses and a luminosity of 1,300 times the Sun's.[1] This star was observed to be double in speckle interferometric observations in 1988, but this has not been confirmed by later infrared observations.[12][13]

Visual companion

CCDM J06288-0702D
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Monoceros
Right ascension 06h 28m 50.3s[14]
Declination −07° 01′ 41″[14]
Apparent magnitude (V) 12.2[14]
Position (relative to A)
Epoch of observation1999
Angular distance25.4″ [4]
Position angle47° [4]
Other designations
ADS 5107 D, BD−06°1574D, WDS 06288-0702D.[14][4]
Database references
SIMBADdata

The triple star system has a visual companion, CCDM J06288-0702D, which has an apparent visual magnitude of approximately 12 and is visible approximately 25 arcseconds away from β Monocerotis A.[4] It is probably not physically close to the other three stars, merely appearing next to them in the sky.[1]

Notes

  1. ↑ 1.0 1.1 1.2 From apparent magnitude and parallax.
  2. ↑ 2.0 2.1 2.2 The Hipparcos Catalogue entry for HIP 30867 includes all three of β Monocerotis A, B, and C. See component 1, component 2, and component 3, entries for HIP 30867, The Hipparcos and Tycho Catalogues, 1997, CDS ID I/239, accessed on line November 21, 2008.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 Beta Mon, Jim Kaler, Stars. Accessed on line November 21, 2008.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 HR 2356, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line November 21, 2008.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 HD 45725 -- Be Star, database entry, SIMBAD. Accessed on line November 21, 2008.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Entry 06288-0702, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line November 21, 2008.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Entry, component 2, HIP 30867, The Hipparcos and Tycho Catalogues, 1997, CDS ID I/239, accessed on line November 21, 2008.
  6. ↑ 6.0 6.1 6.2 6.3 HD 45726 -- Star in double system, database entry, SIMBAD. Accessed on line November 21, 2008.
  7. ↑ 7.0 7.1 7.2 HR 2357, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line November 21, 2008.
  8. ↑ CCDM J06288-0702B, entry, CCDM (Catalog of Components of Double & Multiple stars), Dommanget et al., 2002, CDS ID I/274.
  9. ↑ 9.0 9.1 9.2 9.3 9.4 Entry, component 3, HIP 30867, The Hipparcos and Tycho Catalogues, 1997, CDS ID I/239, accessed on line November 21, 2008.
  10. ↑ 10.0 10.1 10.2 10.3 10.4 HD 45727 -- Emission-line Star, database entry, SIMBAD. Accessed on line November 21, 2008.
  11. ↑ HR 2358, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line November 21, 2008.
  12. ↑ Table 1, ICCD speckle observations of binary stars. X - A further survey for duplicity among the bright stars, Harold A. McAlister, Brian D. Mason, William I. Hartkopf, and Michael M. Shara, Astronomical Journal 106, #4 (October 1993), pp. 1639–1655, doi:10.1086/116753, Bibcode: 1993AJ....106.1639M.
  13. ↑ §4.1, A near IR adaptive optics search for faint companions to early-type multiple stars, A. A. Tokovinin, A. Chalabaev, N. I. Shatsky, and J. L. Beuzit, Astronomy and Astrophysics 346 (June 1999), pp. 481–486, Bibcode: 1999A&A...346..481T.
  14. ↑ 14.0 14.1 14.2 14.3 BD-06 1574D -- Star in double system, database entry, SIMBAD. Accessed on line November 21, 2008.