Chi1 Orionis

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Chi1 Orionis A
Chi 1 orionis diagram vectorized.svg
Star map of the Bayers Stars in Orion. Chi1 Orionis is indicated.
Observation data
Epoch J2000      Equinox J2000
Constellation Orion
Right ascension  05h 54m 22.98s[1]
Declination +20° 16′ 34.2″[1]
Apparent magnitude (V) 4.39
Spectral type G0 V
U−B color index 0.07
B−V color index 0.59
Radial velocity (Rv)−13.4 km/s
Proper motion (μ) RA: −162.54 ± 0.28[1] mas/yr
Dec.: −99.51 ± 0.16[1] mas/yr
Parallax (π)115.43 ± 0.27[1] mas
Distance28.26 ± 0.07 ly
(8.66 ± 0.02 pc)
Absolute magnitude (MV)4.82±0.005[2]
PrimaryChi1 Orionis A
CompanionChi1 Orionis B
Period (P)5156.291±2.508 d
Semi-major axis (a)89.662±0.880 Mas
Eccentricity (e)0.452±0.002
Inclination (i)95.937±0.790°
Longitude of the node (Ω)126.360±0.593°
Periastron epoch (T)2451468.2±3.083 JD
Argument of periastron (ω)
Semi-amplitude (K1)
1.876±0.003 km/s
Radius0.979 ± 0.009[4] R
Luminosity1.081 ± 0.018[4] L
Temperature5,955 ± 6.1[5] K
Metallicity [Fe/H]−0.01[6] dex
Rotation5.2 days[6]
Age300–400[7] Myr
Other designations
54 Ori, Gl 222, HR 2047, BD+20° 1162, HD 39587, LTT 11743, GCTP 1354.00, SAO 77705, HIP 27913.
Database references

Chi1 Orionis1 Ori, χ1 Orionis) is a star about 28 light years away.[1] It is in the constellation Orion, where it can be seen in the tip of the Hunter's upraised club.[8]

χ1 Ori is a G0V star.[9] It has a faint companion with a mass estimated at about 15% of the mass of the Sun, an orbital period of 14.1 years, and an estimated stellar class of M6. The companion orbits an average distance of 6.1 AU from the primary, but has a fairly high orbital eccentricity, ranging from 3.3 AU out to 8.9 AU from the primary. Because of this red dwarf companion, the likelihood of habitable planets in this system is low.

A necessary condition for the existence of a planet in this system are stable zones where the object can remain in orbit for long intervals. For hypothetical planets in a circular orbit around the individual members of this star system, this maximum orbital radius is computed to be 1.01 AU for the primary and 0.41 AU for the secondary. (Note that the orbit of the Earth is 1 AU from the Sun.) A planet orbiting outside of both stars would need to be at least 18.4 AU distant.[10]

χ1 Ori is a candidate stream star member of the Ursa Major Moving Group, although there is some evidence to the contrary.[6]

See also[edit]


  1. ^ a b c d e f 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. Vizier catalog entry
  2. ^ Park, Sunkyung; et al. (2013), "Wilson-Bappu Effect: Extended to Surface Gravity", The Astronomical Journal, 146 (4): 73, arXiv:1307.0592, Bibcode:2013AJ....146...73P, doi:10.1088/0004-6256/146/4/73.
  3. ^ Han, Inwoo; Gatewood, George (2002). "A Precise Orbit Determination of χ1Orionis from Astrometric and Radial Velocity Data". Publications of the Astronomical Society of the Pacific. 114 (792): 224–228. Bibcode:2002PASP..114..224H. doi:10.1086/338367.
  4. ^ a b Boyajian, Tabetha S.; et al. (February 2012), "Stellar Diameters and Temperatures. I. Main-sequence A, F, and G Stars", The Astrophysical Journal, 746 (1): 101, arXiv:1112.3316, Bibcode:2012ApJ...746..101B, doi:10.1088/0004-637X/746/1/101. See Table 10.
  5. ^ Kovtyukh; et al. (2003), "High precision effective temperatures for 181 F-K dwarfs from line-depth ratios", Astronomy and Astrophysics, 411 (3): 559–564, arXiv:astro-ph/0308429, Bibcode:2003A&A...411..559K, doi:10.1051/0004-6361:20031378
  6. ^ a b c Maldonado, J.; et al. (October 2010), "A spectroscopy study of nearby late-type stars, possible members of stellar kinematic groups", Astronomy and Astrophysics, 521: A12, arXiv:1007.1132, Bibcode:2010A&A...521A..12M, doi:10.1051/0004-6361/201014948
  7. ^ Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008), "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics", The Astrophysical Journal, 687 (2): 1264–1293, arXiv:0807.1686, Bibcode:2008ApJ...687.1264M, doi:10.1086/591785
  8. ^ Jim Kaler, Chi-1 Orionis.
  9. ^ König, B.; Fuhrmann, K.; Neuhäuser, R.; Charbonneau, D.;Jayawardhana, R., Direct detection of the companion of chi1 Orionis Archived 2015-04-02 at the Wayback Machine Astronomy and Astrophysics, vol. 394, L43, 2002.
  10. ^ Jaime, Luisa G.; et al. (December 2012), "Regions of dynamical stability for discs and planets in binary stars of the solar neighbourhood", Monthly Notices of the Royal Astronomical Society, 427 (4): 2723–2733, arXiv:1208.2051, Bibcode:2012MNRAS.427.2723J, doi:10.1111/j.1365-2966.2012.21839.x.

External links[edit]