Theta Cancri

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Theta Cancri
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cancer
Right ascension  08h 31m 35.72962s[1]
Declination +18° 05′ 39.9160″[1]
Apparent magnitude (V) +5.323[2]
Spectral type K5 III[3]
U−B color index +1.949[2]
B−V color index +1.565[2]
Radial velocity (Rv)+44.47±0.19[4] km/s
Proper motion (μ) RA: −60.85[1] mas/yr
Dec.: −56.14[1] mas/yr
Parallax (π)7.86 ± 0.29[1] mas
Distance410 ± 20 ly
(127 ± 5 pc)
Absolute magnitude (MV)−0.19[5]
Luminosity353[5] L
Other designations
θ Cnc, 31 Cancri, BD+18° 1963, FK5 2667, HD 72094, HIP 41822, HR 3357, SAO 97881[6]
Database references

Theta Cancri, Latinized from θ Cancri, is a multiple star[7][3] system in the zodiac constellation of Cancer, 410 light years from Earth. The primary, component A, is classified as an orange K-type giant with an apparent magnitude of +5.32.[2] Since it is near the ecliptic, it can be occulted by the Moon[8] and, very rarely, by planets.

In Chinese astronomy, Ghost (Chinese: 鬼宿; pinyin: Guǐ Xiù) refers to an asterism consisting of Theta Cancri, Eta Cancri, Gamma Cancri and Delta Cancri.[9] Theta Cancri is the first star of Ghost (Chinese: 鬼宿一; pinyin: Guǐ Xiù yī), as it is also the determinative star for that asterism.[10]


  1. ^ a b c d e 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.
  2. ^ a b c d Gutierrez-Moreno, Adelina; et al. (1966), A System of photometric standards, 1, Publicaciones Universidad de Chile, Department de Astronomy, pp. 1–17, Bibcode:1966PDAUC...1....1G.
  3. ^ a b Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  4. ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  5. ^ a b Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  6. ^ "tet Cnc -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-06-19.
  7. ^ Hartkopf, W. I.; McAlister, H. A. (January 1984), "Binary stars unresolved by speckle interferometry. III", Publications of the Astronomical Society of the Pacific, 96: 105–116, Bibcode:1984PASP...96..105H, doi:10.1086/131309.
  8. ^ White, Nathaniel M.; Feierman, Barry H. (September 1987), "A Catalog of Stellar Angular Diameters Measured by Lunar Occultation", Astronomical Journal, 94: 751, Bibcode:1987AJ.....94..751W, doi:10.1086/114513.
  9. ^ 陳久金 (2005). Zhōngguó Xīngzuò Shénhuà 中國星座神話 [Chinese Constellation Mythology]. 台灣古籍出版有限公司. p. 394. ISBN 978-986-7332-25-7.
  10. ^ 陳久金 (2005). Zhōngguó Xīngzuò Shénhuà 中國星座神話 [Chinese Constellation Mythology]. 台灣古籍出版有限公司. p. 193. ISBN 978-986-7332-25-7.