Eta2 Coronae Australis

η2 Coronae Australis, Latinized as Eta2 Coronae Australis, is a single[9] star located in the southern constellation of Corona Australis. It is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of 5.587.[2] Parallax measurements yield a distance estimate of 480 light-years from the Sun,[1] but it is drifting closer with a radial velocity of −23 km/s.[5]

η2 Coronae Australis
Observation data
Epoch J2000      Equinox J2000
Constellation Corona Australis
Right ascension 18h 49m 34.99512s[1]
Declination −43° 26′ 02.7458″[1]
Apparent magnitude (V) 5.587[2]
Spectral type B9IV[3]
B−V color index −0.08[4]
Radial velocity (Rv)−23.0±4.3[5] km/s
Proper motion (μ) RA: −1.990[1] mas/yr
Dec.: −25.755[1] mas/yr
Parallax (π)4.1131 ± 0.2190[1] mas
Distance790 ± 40 ly
(240 ± 10 pc)
Absolute magnitude (MV)−0.75[6]
Mass3.23±0.08 M
Temperature10,940±255 K
Rotational velocity (v sin i)30 km/s
Age213[8] Myr
Other designations
Eta2 CrA, CD−43°12854, HD 173861, HIP 92382, HR 7068, SAO 229307
Database references

This object has a stellar classification of B9IV,[3] matching a B-type subgiant star. It is 213[8] million years old with a mass of 3.23 times that of the Sun. The star is radiating 171 times the luminosity of the Sun from its photosphere at an effective temperature of 10,940 K.[7]


  1. ^ a b c d e f Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. ^ a b Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
  3. ^ a b Houk, N. (1987). "Michigan Catalogue of two dimensional spectral types for the HD stars". Michigan Spectral Survey. 2.
  4. ^ Corben, P. M.; Stoy, R. H. (1968). "Photoelectric Magnitudes and Colours for Bright Southern Stars". Monthly Notes of the Astronomical Society of Southern Africa. 27: 11. Bibcode:1968MNSSA..27...11C.
  5. ^ a b Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
  6. ^ Philip, A. Davis; Egret, D. (1980). "An Analysis of the Hauck / Mermilliod Catalogue of Homgeneous Four-Color Data - Part Two". Astronomy and Astrophysics Supplement. 40: 199. Bibcode:1980A&AS...40..199P.
  7. ^ a b Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691.
  8. ^ a b Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035.
  9. ^ 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.