Chi2 Orionis

Source: Wikipedia, the free encyclopedia.
For other stars with this Bayer designation, see χ Orionis.
χ2 Orionis
Location of χ2 Orionis (circled)
Observation data
ICRS
)
Constellation Orion
Right ascension 06h 03m 55.18437s[1]
Declination +20° 08′ 18.4281″[1]
Apparent magnitude (V) 4.63[2][3]
Characteristics
Spectral type B2Ia[2]
U−B color index −0.68[3]
B−V color index +0.28[3]
R−I color index +0.22[3]
Variable type α Cyg[4]
Distance
approx. 4,300 ly
(approx. 1,300 pc)
Absolute magnitude (MV)−7.6[2]
Details
Myr
HIP 28716, HR 2135, PPM 95316, SAO
 77911
Database references
SIMBADdata

Chi2 Orionis (Chi2 Ori / χ2 Orionis / χ2 Ori)

apparent visual magnitude of 4.63 but being quite distant, and heavily extinguished it burns with the greatest absolute visual light magnitude among stars in Orion within the near reaches of the galaxy, 0.9 of a magnitude brighter than Rigel.[citation needed] Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It is considered to be a member of the Gemini OB1 association.[2]

In apparent brightness it ranks, within Orion, admitting the higher published mean brightness of much more variable stars ranked above it, 35th.[citation needed]

Chi1 Orionis is an unrelated, yellow, main sequence star over two degrees away.

Spectrum

χ2 Orionis has a B2

bright supergiant spectrum and is one of the standard B2 Ia stars.[7] It has been reported as having unusually narrow absorption lines and some weak emission lines and was included as one of the original Be stars.[8] It is no longer treated as a Be star since many supergiants show some emission features at high resolution and Be stars is usually defined to exclude supergiants.[9]

Variability

A light curve for Chi2 Orionis, plotted from Hipparcos data[10]

χ2 Orionis was listed as having likely small amplitude variability in photometry for the Third Catalogue of Stars measured in the Geneva Observatory Photometric System, specifically varying by 22 thousandths of a magnitude.[11] It was included in the General Catalogue of Variable Stars based on Hipparcos satellite photometry with a magnitude range (in the Hipparchos photometric system) of 4.68 - 4.72 and a period of 2.8 days.[12] A detailed study of the Hipparcos photometry confirmed the star as an α Cyg variable and gave the amplitude of variation as 0.057 magnitudes.[13]

References

  1. ^
    S2CID 244398875
    . Gaia DR3 record for this source at VizieR.
  2. ^
    S2CID 18815761
    .
  3. ^
    CDS ID V/50
    . Accessed on line January 14, 2011.
  4. ^ khi 2 Ori, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars Archived 2017-06-20 at the Wayback Machine, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line January 14, 2011.
  5. Bibcode:1953GCRV..C......0W
    .
  6. ^
    S2CID 118629873
    .
  7. Bibcode:1993AAS...183.1710G, archived from the original
    on 2019-06-25, retrieved 2012-02-04
  8. doi:10.1086/142899
    .
  9. Bibcode:1994A&AS..103..135A
    .
  10. ^ "Light Curve". Hipparcos ESA. ESA. Retrieved 11 August 2022.
  11. Bibcode:1982A&AS...48..503R
    .
  12. Bibcode:1999IBVS.4659....1K
    .
  13. doi:10.1051/0004-6361/200912304
    .
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