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
Distance 28.26 ± 0.07 ly
(8.66 ± 0.02 pc)
Absolute magnitude (MV) 4.67
Radius 0.979 ± 0.009[2] R
Luminosity 1.081 ± 0.018[2] L
Temperature 5,955 ± 6.1[3] K
Metallicity [Fe/H] −0.01[4] dex
Rotation 5.2 days[4]
Age 300–400[5] Myr
Other designations
54 Ori, Gl 222 A, HR 2047, BD +20°1162, HD 39587, LTT 11743, GCTP 1354.00, SAO 77705, HIP 27913.

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.[6]

χ1 Ori is a G0V star.[7] 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.[8]

χ1 Ori is a candidate stream star member of the Ursa Major Moving Group, although there is some evidence to the contrary.[4]

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:0708.1752free to read. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ 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:1112.3316free to read, Bibcode:2012ApJ...746..101B, doi:10.1088/0004-637X/746/1/101 . See Table 10.
  3. ^ 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/0308429free to read, Bibcode:2003A&A...411..559K, doi:10.1051/0004-6361:20031378 
  4. ^ 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:1007.1132free to read, Bibcode:2010A&A...521A..12M, doi:10.1051/0004-6361/201014948 
  5. ^ 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:0807.1686free to read, Bibcode:2008ApJ...687.1264M, doi:10.1086/591785 
  6. ^ Jim Kaler, Chi-1 Orionis.
  7. ^ König, B.; Fuhrmann, K.; Neuhäuser, R.; Charbonneau, D.;Jayawardhana, R., Direct detection of the companion of chi1 Orionis Astronomy and Astrophysics, vol. 394, L43, 2002.
  8. ^ 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:1208.2051free to read, Bibcode:2012MNRAS.427.2723J, doi:10.1111/j.1365-2966.2012.21839.x. 

External links[edit]