31 Orionis

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]

  1. ^ a b c d e f g h Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference XHIP was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Hoffleit1991 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference MermiliodUBV was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference VSX was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference gcvs was invoked but never defined (see the help page).
  8. ^ a b c d e Cite error: The named reference dr3a was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference deMedeiros2014 was invoked but never defined (see the help page).
  10. ^ a b c d e f g Cite error: The named reference dr3b was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference CDS was invoked but never defined (see the help page).