Theta Coronae Australis

Theta Coronae Australis, Latinized from θ Coronae Australis, is a star located in the constellation Corona Australis. Theta Coronae Australis is also known as HR 6951, and HD 170845.[8] Parallax measurements by Hipparcos put it at a distance of roughly 560 light-years, or 171 parsecs, away from the Solar System.[1]

θ Corona Australis
Observation data
Epoch J2000      Equinox J2000
Constellation Corona Australis
Right ascension 18h 33m 30.18626s[1]
Declination −42° 18′ 45.0335″[1]
Apparent magnitude (V) 4.64[2]
Spectral type G5 III[2]
U−B color index +0.76[3]
B−V color index +1.02[3]
Radial velocity (Rv)−2.1±2[4] km/s
Proper motion (μ) RA: 33.27[1] mas/yr
Dec.: -20.72[1] mas/yr
Parallax (π)5.85 ± 0.27[1] mas
Distance560 ± 30 ly
(171 ± 8 pc)
Absolute magnitude (MV)−1.54[5]
Radius11[2] R
Luminosity497[5] L
[6] K
Rotational velocity (v sin i)11.8±1.0[7] km/s
Other designations
CD−42° 13378, FK5 697, HD 170845, HIP 90982, HR 6951, SAO 229111[8]
Database references

Theta Coronae Australis is a G-type giant star that is radiating 497[5] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,794 K.[6] It has an apparent visual magnitude of 4.64,[2] and is about 11 times wider than the Sun.[2] Theta Coronae Australis has an unusually high rate of rotation for an evolved star of this type, showing a projected rotational velocity of 11.8 km/s.[7] One possible explanation is that it may have engulfed a nearby giant planet, such as a hot Jupiter.[9]


  1. ^ a b c d e f van Leeuwen, F.; et al. (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 e Pasinetti Fracassini, L. E.; et al. (2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics". Astronomy & Astrophysics. 367: 521–24. arXiv:astro-ph/0012289. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451.
  3. ^ a b Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
  4. ^ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Bibcode:1953GCRV..C......0W. Cite journal requires |journal= (help)
  5. ^ a b c 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. ^ a b Ammons, S. Mark; Robinson, Sarah E.; Strader, Jay; Laughlin, Gregory; Fischer, Debra; Wolf, Aaron (2006). "The N2K Consortium. IV. New Temperatures and Metallicities for More than 100,000 FGK Dwarfs". The Astrophysical Journal. 638 (2): 1004. arXiv:astro-ph/0510237. Bibcode:2006ApJ...638.1004A. doi:10.1086/498490.
  7. ^ a b De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (2014). "A catalog of rotational and radial velocities for evolved stars". Astronomy & Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762.
  8. ^ a b "* tet CrA". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 17 August 2017.
  9. ^ Rodrigues da Silva, R.; Canto Martins, B. L.; De Medeiros, J. R. (March 2015). "On the Nature of Rapidly Rotating Single Evolved Stars". The Astrophysical Journal. 801 (1): 6. arXiv:1503.03447. Bibcode:2015ApJ...801...54R. doi:10.1088/0004-637X/801/1/54. 54.