Chi Ophiuchi

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χ Ophiuchi
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Ophiuchus
Right ascension 16h 27m 01.4349s[1]
Declination −18° 27′ 22.504″[1]
Apparent magnitude (V) 4.18 to 5.0[2]
Spectral type B2Vne[1]
U−B color index −0.75[3]
B−V color index +0.28[3]
R−I color index +0.22[3]
Variable type GCAS[2] + LERI[4]
Radial velocity (Rv) −3.2 ± 5[1] km/s
Proper motion (μ) RA: −5.58[1] mas/yr
Dec.: −22.22[1] mas/yr
Parallax (π) 6.67 ± 0.74[1] mas
Distance approx. 490 ly
(approx. 150 pc)
Absolute magnitude (MV) −4.6[5]
Mass 10.1 ± 0.7[6] M
Radius 4.5[7] R
Luminosity 200,000[5] L
Surface gravity (log g) 4.13[5] cgs
Temperature 41,700[5] K
Rotational velocity (v sin i) 134[3] km/s
Age 22.5 ± 2.6[6] Myr
Other designations
χ Oph, Chi Ophiuchi, Chi Oph, 7 Ophiuchi, 7 Oph, BD−18 4282, FK5 3298, GC 22117, HD 148184, HIP 80569, HR 6118, PPM 231703, SAO 159918.[1]
Database references

Chi Ophiuchi (Chi Oph / χ Ophiuchi / χ Oph) is a Be star in the constellation of Ophiuchus.[1] It has an apparent visual magnitude which varies between 4.18 and 5.0.[2]

This star is a proper motion member of the Upper Scorpius sub-group in the Scorpius-Centaurus OB association, the nearest such co-moving association of massive stars to the Sun.[5]


  1. ^ a b c d e f g h i * chi Oph -- Be Star, database entry, SIMBAD. Accessed on line January 12, 2011.
  2. ^ a b c khi Oph, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line January 12, 2011.
  3. ^ a b c d HR 6118, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line January 12, 2011.
  4. ^ Watson, C. L. (2006). "The International Variable Star Index (VSX)". The Society for Astronomical Sciences 25th Annual Symposium on Telescope Science. Held May 23-25. 25: 47. Bibcode:2006SASS...25...47W. 
  5. ^ a b c d e de Geus, E. J.; de Zeeuw, P. T.; Lub, J. (June 1989), "Physical parameters of stars in the Scorpio-Centaurus OB association", Astronomy and Astrophysics, 216 (1–2): 44–61, Bibcode:1989A&A...216...44D 
  6. ^ a b Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883Freely accessible, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x 
  7. ^ HD 148184, database entry, Catalog of Apparent Diameters and Absolute Radii of Stars (CADARS), 3rd edition, L. E. Pasinetti-Fracassini, L. Pastori, S. Covino, and A. Pozzi, CDS ID II/224. Accessed on line January 12, 2011.