| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 29m 43.98147s |
| Declination | −01° 05′ 32.0582″ |
| Apparent magnitude (V) | 4.71 + 10.2 |
| Characteristics | |
| Spectral type | K5III + F7V |
| U−B color index | +1.91 |
| B−V color index | +1.58 |
| Variable type | SR? |
| Astrometry | |
| Radial velocity (Rv) | +6.02±0.15 km/s |
| Proper motion (μ) | RA: +1.242 mas/yr Dec.: −25.476 mas/yr |
| Parallax (π) | 6.6135 ± 0.2293 mas |
| Distance | 490 ± 20 ly (151 ± 5 pc) |
| Absolute magnitude (MV) | −1.23 |
| Details | |
| 31 Ori A | |
| Mass | 5.2 M☉ |
| Radius | 62 R☉ |
| Luminosity | 1,361 L☉ |
| Surface gravity (log g) | 0.92 cgs |
| Temperature | 4,610 K |
| Metallicity [Fe/H] | −0.21 dex |
| Rotational velocity (v sin i) | 2.7 km/s |
| 31 Ori B | |
| Mass | 1.1 M☉ |
| Radius | 1.2 R☉ |
| Luminosity | 1.9 L☉ |
| Surface gravity (log g) | 4.24 cgs |
| Temperature | 6,111 K |
| Metallicity [Fe/H] | −0.23 dex |
| Age | 3.9 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
31 Orionis is a binary star 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. The distance to this system is approximately 490 light years away based on parallax, and it is drifting further away with a mean radial velocity of +6 km/s.
As of 2008, the pair had an angular separation of 12.7″. The brighter member, designated component A, is an aging giant star with a stellar classification of K5III. It is reported as a semi-regular variable with magnitude ranging from 4.68 to 4.72 over 141 days, although the General Catalogue of Variable Stars describes this as unconfirmed by subsequent observations. 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.
References
- ^ 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.
- ^ 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
- ^ 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
- ^ 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.
- ^ 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
- ^ a b "CI Ori". The International Variable Star. AAVSO – American Association of Variable Star Observers. Retrieved 6 August 2016.
- ^ 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.
- ^ 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.
- ^ 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
- ^ 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.
- ^ "31 Ori". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-06-27.
- ^ "/ftp/cats/more/HIP/cdroms/cats". Centre de Données astronomiques de Strasbourg. Strasbourg astronomical Data Center. Retrieved 15 October 2022.