Delta Monocerotis

Delta Monocerotis, which is Latinized from δ Monocerotis, is a single star[12] in the constellation of Monoceros, positioned about a half degree south of the celestial equator. It has a white hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.15.[2] The distance to this star is approximately 384 light years based on parallax.[7] It is drifting further away from the Sun with a radial velocity of about +15 km/s,[6] having come to within 88 light-years some 7.3 million years ago.[2] The star has an absolute magnitude of −1.20.[2]

Delta Monocerotis
Location of δ Monocerotis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Monoceros
Right ascension 07h 11m 51.860s[1]
Declination −00° 29′ 33.96″[1]
Apparent magnitude (V) 4.15[2]
Characteristics
Spectral type A2V[3] or A0IV[4]
U−B color index +0.04[5]
B−V color index +0.00[5]
Astrometry
Radial velocity (Rv)+15.0±4.1[6] km/s
Proper motion (μ) RA: +0.79[7] mas/yr
Dec.: +4.52[7] mas/yr
Parallax (π)8.49 ± 0.17[7] mas
Distance384 ± 8 ly
(118 ± 2 pc)
Absolute magnitude (MV)−1.20[2]
Details
Mass2.4+0.43
−0.38[3] M☉
Luminosity350[8] L☉
Surface gravity (log g)3.5±0.25[3] cgs
Temperature9,462[8] K
Metallicity [Fe/H]0.00[9] dex
Rotational velocity (v sin i)175.5±1.3[10] km/s
Age405+135
−207[3] Myr
Other designations
δ Mon, 22 Monocerotis, BD−00°1636, FK5 1187, GC 9518, HD 55185, HIP 34769, HR 2714, SAO 134330, CCDM J07119-0030A, WDS J07119-0030A[11]
Database references
SIMBADdata

The Bright Star Catalogue assigns this star a stellar classification of A2V, suggesting this is an A-type main-sequence star.[3][13] However, Houk and Swift (1999) found a more evolved subgiant class of A0IV.[4] It has around 2.4 times the mass of the Sun and is an estimated 405 million years old.[3] The star has a high rate of spin with a projected rotational velocity of 175.5 km/s,[10] giving it an equatorial bulge that is 5% larger than the polar radius.[14] It is radiating 350 times the luminosity of the Sun from its photosphere at an effective temperature of 9,462 K.[8]

It has one reported visual companion, designated component B, at an angular separation of 32.0″ and visual magnitude 13.0.[15]

References
  1. Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H.
  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. S2CID 119257644. Vizier catalog entry
  3. Gullikson, Kevin; et al. (August 2016). "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars". The Astronomical Journal. 152 (2): 13. arXiv:1604.06456. Bibcode:2016AJ....152...40G. doi:10.3847/0004-6256/152/2/40. S2CID 119179065. 40.
  4. Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
  5. Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42 (2): 443. Bibcode:2014JAVSO..42..443M.Vizier catalog entry
  6. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  7. 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. Vizier catalog entry
  8. Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. S2CID 55586789. Vizier catalog entry
  9. Gontcharov, G. A. (2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters. 38 (12): 771–782. arXiv:1606.08814. Bibcode:2012AstL...38..771G. doi:10.1134/S1063773712120031. S2CID 118345778. Vizier catalog entry
  10. Díaz, C. G.; et al. (July 2011). "Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum". Astronomy & Astrophysics. 531: A143. arXiv:1012.4858. Bibcode:2011A&A...531A.143D. doi:10.1051/0004-6361/201016386. S2CID 119286673.
  11. "del Mon". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-08-29.
  12. 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. S2CID 14878976.
  13. Hoffleit, D.; Warren, W. H. (1995). "Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
  14. 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. S2CID 119273474.
  15. Dommanget, J.; Nys, O. (2002). "VizieR Online Data Catalog: CCDM (Catalog of Components of Double & Multiple stars) (Dommanget+ 2002)". VizieR On-line Data Catalog: I/274. Originally Published in: Observations et Travaux 54. 1274. Bibcode:2002yCat.1274....0D. Vizier catalog entry
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