Eta1 Coronae Australis

Eta1 Coronae Australis, Latinized from η1 CrA, is a suspected astrometric binary[11] star system in the constellation of Corona Australis. It is visible to the naked eye as a dim, white-hued point of light with an apparent visual magnitude of 5.456.[2] Parallax measurements put it at a distance of 317 light-years away from the Sun.

η1 Coronae Australis
Observation data
Epoch J2000      Equinox J2000
Constellation Corona Australis
Right ascension 18h 48m 50.49216s[1]
Declination −43° 40′ 48.1977″[1]
Apparent magnitude (V) 5.456[2]
Spectral type A3V[3]
B−V color index +0.13[4]
Radial velocity (Rv)−4.0±4.2[5] km/s
Proper motion (μ) RA: 22.312[1] mas/yr
Dec.: −14.139[1] mas/yr
Parallax (π)10.2735 ± 0.1889[1] mas
Distance317 ± 6 ly
(97 ± 2 pc)
Absolute magnitude (MV)0.84[6]
Radius2.2[7] R
Luminosity57.72[8] L
Surface gravity (log g)4.04[6] cgs
[9] K
Rotational velocity (v sin i)122.3[10] km/s
Other designations
Eta1 CrA, CD−43° 12841, FK5 1490, HD 173715, HIP 92308, HR 7062, SAO 229299
Database references

The visible component is an A-type main-sequence star with a stellar classification of A3V,[3] which indicates it is generating energy through core hydrogen fusion. It has broad spectrum absorption lines associated with its rotation period, having a projected rotational velocity of 122.3 km/s.[10] The star is radiating 58[8] times the luminosity of the Sun from its photosphere at an effective temperature of 8,371 K.[9]


  1. ^ a b c d e 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, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. 2. Ann Arbor: Dept. of Astronomy, University of Michigan.
  4. ^ Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
  5. ^ 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. S2CID 119231169.
  6. ^ a b 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. ^ Pasinetti Fracassini, L. E.; et al. (February 2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics". Astronomy and Astrophysics. 367 (2): 521–524. arXiv:astro-ph/0012289. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451. S2CID 425754.
  8. ^ 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, S2CID 119257644.
  9. ^ 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): 1004–1017. arXiv:astro-ph/0510237. Bibcode:2006ApJ...638.1004A. doi:10.1086/498490. S2CID 118834752.
  10. ^ a b Díaz, C. G.; González, J. F.; Levato, H.; Grosso, M. (2011). "Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum". Astronomy & Astrophysics. 531: A143. arXiv:1012.4858. Bibcode:2011A&A...531A.143D. doi:10.1051/0004-6361/201016386. S2CID 119286673.
  11. ^ 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, S2CID 14878976.