31 Orionis
Location of 31 Orionis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Orion
Right ascension 05h 29m 43.98147s[1]
Declination −01° 05′ 32.0582″[1]
Apparent magnitude (V) 4.71[2] + 10.2[3]
Characteristics
Spectral type K5III[4] + F7V[3]
U−B color index +1.91[5]
B−V color index +1.58[5]
Variable type SR?[6][7]
Astrometry
Radial velocity (Rv)+6.02±0.15[1] km/s
Proper motion (μ) RA: +1.242[1] mas/yr
Dec.: −25.476[1] mas/yr
Parallax (π)6.6135 ± 0.2293 mas[1]
Distance490 ± 20 ly
(151 ± 5 pc)
Absolute magnitude (MV)−1.23[2]
Details
31 Ori A
Mass5.2[8] M☉
Radius62[8] R☉
Luminosity1,361[8] L☉
Surface gravity (log g)0.92[8] cgs
Temperature4,610[8] K
Metallicity [Fe/H]−0.21[2] dex
Rotational velocity (v sin i)2.7[9] km/s
31 Ori B
Mass1.1[10] M☉
Radius1.2[10] R☉
Luminosity1.9[10] L☉
Surface gravity (log g)4.24[10] cgs
Temperature6,111[10] K
Metallicity [Fe/H]−0.23[10] dex
Age3.9[10] Gyr
Other designations
31 Ori, CI Ori, BD−01°913, GC 6792, HD 36167, HIP 25737, HR 1834, SAO 132176, CCDM J05297-0106A, WDS J05297-0106A[11]
Database references
SIMBADdata

31 Orionis is a binary star[3] system in the equatorial constellation of Orion, located near the bright star Mintaka. It is visible to the naked eye as a faint, orange-hued point of light with a baseline apparent visual magnitude of 4.71.[2] The distance to this system is approximately 490 light years away based on parallax,[1] and it is drifting further away with a mean radial velocity of +6 km/s.[1]

A light curve for CI Orionis, plotted from Hipparcos data[12]

As of 2008, the pair had an angular separation of 12.7″.[3] The brighter member, designated component A, is an aging giant star with a stellar classification of K5III.[4] It is reported as a semi-regular variable with magnitude ranging from 4.68 to 4.72 over 141 days,[6] although the General Catalogue of Variable Stars describes this as unconfirmed by subsequent observations.[7] It has the variable star designation CI Orionis, while 31 Orionis is the Flamsteed designation. The magnitude 10.2 companion star, component B, is an F-type main-sequence star with a class of F7V.[3]

References

  1. ^ a b c d e f g h 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. ^ a b c d 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. ^ a b c d e Eggleton, P. P.; Tokovinin, A. A. (2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976. Vizier catalog entry
  4. ^ a b Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: 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.
  5. ^ a b Mermilliod, J. C. (2006). "Homogeneous Means in the UBV System (Mermilliod 1991)". VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie. 2168. Bibcode:2006yCat.2168....0M.Vizier catalog entry
  6. ^ a b "CI Ori". The International Variable Star. AAVSO – American Association of Variable Star Observers. Retrieved 6 August 2016.
  7. ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009). "General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. 1. Bibcode:2009yCat....102025S.
  8. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  9. ^ De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (2014). "A catalog of rotational and radial velocities for evolved stars". Astronomy & Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762. S2CID 54046583. Vizier catalog entry
  10. ^ a b c d e f g Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  11. ^ "31 Ori". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-06-27.
  12. ^ "/ftp/cats/more/HIP/cdroms/cats". Centre de Données astronomiques de Strasbourg. Strasbourg astronomical Data Center. Retrieved 15 October 2022.
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