Beta Monocerotis

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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 the scope's focus). William Herschel who discovered it in 1781 commented that it is "one of the most beautiful sights in the heavens". 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[edit]

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
Distance approx. 700 ly
(approx. 210 pc)
Absolute magnitude (MV) −2.0[note 1]
Details
Mass 7[1] M
Luminosity 3,200[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
SIMBAD data

Beta Monocerotis A (Beta Mon A, β Monocerotis A, β Mon A) is a Be shell star with a mass of approximately 7 solar masses and a luminosity of 3,200 times the Sun's.[1][5]

Beta Monocerotis B[edit]

β Monocerotis B
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Monoceros
Right ascension 06h 28m 49.424s[6]
Declination −07° 02′ 03.88″[6]
Apparent magnitude (V) 5.40[7]
Characteristics
Spectral type B3ne[7]
U−B color index −0.52[8]
B−V color index −0.07[8]
Astrometry
Radial velocity (Rv) 18 ± 5[7] km/s
Proper motion (μ) RA: −7.00[6] mas/yr
Dec.: −4.97[6] mas/yr
Parallax (π) 4.72 ± 1.10[6] mas
Distance approx. 700 ly
(approx. 210 pc)
Absolute magnitude (MV) −1[note 1]
Details
Mass 6.2[1] M
Luminosity 1,600[1] L
Rotational velocity (v sin i) 123[8] 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][7][9]
Database references
SIMBAD data

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[edit]

β Monocerotis C
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Monoceros
Right ascension 06h 28m 49.613s[10]
Declination −07° 02′ 04.76″[10]
Apparent magnitude (V) 5.60[11]
Characteristics
Spectral type B3e[11]
B−V color index −0.1[11]
Astrometry
Radial velocity (Rv) 23 ± 5[11] km/s
Proper motion (μ) RA: −7.00[10] mas/yr
Dec.: −4.97[10] mas/yr
Parallax (π) 4.72 ± 1.10[10] mas
Distance approx. 700 ly
(approx. 210 pc)
Absolute magnitude (MV) −1[note 1]
Details
Mass 6[1] M
Luminosity 1,300[1] L
Rotational velocity (v sin i) 331[12] 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.[11][4]
Database references
SIMBAD data

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.[13][14]

Visual companion[edit]

CCDM J06288-0702D
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Monoceros
Right ascension 06h 28m 50.3s[15]
Declination −07° 01′ 41″[15]
Apparent magnitude (V) 12.2[15]
Position (relative to A)
Epoch of observation 1999
Angular distance 25.4 [4]
Position angle 47° [4]
Other designations
ADS 5107 D, BD−06°1574D, WDS 06288-0702D.[15][4]
Database references
SIMBAD data

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[edit]

  1. ^ a b c From apparent magnitude and parallax.
  2. ^ a b c 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[edit]

  1. ^ a b c d e f g h i j k l Beta Mon, Jim Kaler, Stars. Accessed on line November 21, 2008.
  2. ^ a b c d e 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. ^ a b c d e f g h i j HD 45725 -- Be Star, database entry, SIMBAD. Accessed on line November 21, 2008.
  4. ^ a b c d e f g Entry 06288-0702, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line November 21, 2008.
  5. ^ Rivinius, Th.; Štefl, S.; Baade, D. (2006). "Bright Be-shell stars". Astronomy and Astrophysics. 459: 137. Bibcode:2006A&A...459..137R. doi:10.1051/0004-6361:20053008. 
  6. ^ a b c d e Entry, component 2, HIP 30867, The Hipparcos and Tycho Catalogues, 1997, CDS ID I/239, accessed on line November 21, 2008.
  7. ^ a b c d HD 45726 -- Star in double system, database entry, SIMBAD. Accessed on line November 21, 2008.
  8. ^ a b c 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.
  9. ^ CCDM J06288-0702B, entry, CCDM (Catalog of Components of Double & Multiple stars), Dommanget et al., 2002, CDS ID I/274.
  10. ^ a b c d e Entry, component 3, HIP 30867, The Hipparcos and Tycho Catalogues, 1997, CDS ID I/239, accessed on line November 21, 2008.
  11. ^ a b c d e HD 45727 -- Emission-line Star, database entry, SIMBAD. Accessed on line November 21, 2008.
  12. ^ 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.
  13. ^ 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, Bibcode1993AJ....106.1639M.
  14. ^ §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, Bibcode1999A&A...346..481T.
  15. ^ a b c d BD-06 1574D -- Star in double system, database entry, SIMBAD. Accessed on line November 21, 2008.