Lambda Coronae Australis

λ Coronae Australis, Latinized as Lambda Coronae Australis is a binary star[5] system located in the southern constellation of Corona Australis. It is visible to the naked eye as a faint, white-hued point of light with an apparent visual magnitude of 5.11.[2] The system is located at a distance of 205 light-years, based on parallax,[1] and is drifting further away with a radial velocity of −26 km/s.[7]

Lambda Coronae Australis
Observation data
Epoch J2000      Equinox J2000
Constellation Corona Australis
Right ascension 18h 43m 46.94143s[1]
Declination −38° 19′ 24.3941″[1]
Apparent magnitude (V) 5.11[2] + 10.01[3]
Characteristics
Spectral type A0/1V[4] + K0[5]
B−V color index +0.075±0.002[6]
Astrometry
Radial velocity (Rv)−26.40±4.2[7] km/s
Proper motion (μ) RA: +1.047[1] mas/yr
Dec.: −53.774[1] mas/yr
Parallax (π)15.8771 ± 0.2823 mas[1]
Distance205 ± 4 ly
(63 ± 1 pc)
Absolute magnitude (MV)1.15[2]
Details
λ CrA A
Mass2.17±0.10[2] M☉
Radius2.24[2] R☉
Luminosity31.25[6] L☉
Surface gravity (log g)4.08±0.08[2] cgs
Temperature8,609[8] K
Metallicity [Fe/H]−0.30[8] dex
Rotational velocity (v sin i)148.6±1.6[9] km/s
Age273[10] Myr
Other designations
λ CrA, CD−38°13036, HD 172777, HIP 91875, HR 7021, SAO 210501, WDS J18438-3819A[11]
Database references
SIMBADdata

The primary member of this system, designated component A, is an A-type main-sequence star with a stellar classification of A0/1V.[4] It is 273[10] million years old and is spinning with a projected rotational velocity of 149 km/s.[9] This high rotation rate is producing an equatorial bulge that is 7% larger than the polar radius.[12] It has 2.17 times the mass of the Sun and 2.24 times the Sun's radius.[2] The star is radiating 31[6] times the Sun's luminosity from its photosphere at an effective temperature of 8,609 K.[8]

The secondary companion, component B,[13] has an apparent visual magnitude of 10.01[3] and a class of K0.[5] As of 2016, it has an angular separation of 29.5″ from the primary along a position angle of 213°.[3] Component C[14] is a visual companion of magnitude 9.9 and separation 43.3″ from the primary.[3]

References
  1. 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. Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A.
  3. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22
  4. Houk, N.; Smith-Moore, M. (1988). Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Vol. 4. Ann Arbor, MI: Department of Astronomy, University of Michigan. Bibcode:1988mcts.book.....H.
  5. 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.
  6. 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.
  7. 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.
  8. Erspamer, D.; North, P. (2003). "Automated spectroscopic abundances of a and F-type stars using echelle spectrographs. II. Abundances of 140 A-F stars from ELODIE". Astronomy and Astrophysics. 398 (3): 1121–1136. arXiv:astro-ph/0210065. Bibcode:2003A&A...398.1121E. doi:10.1051/0004-6361:20021711. S2CID 1109164.
  9. Díaz, C. G.; et al. (July 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.
  10. David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. S2CID 33401607.
  11. "lam CrA". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-16.
  12. van Belle, Gerard T. (March 2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review. 20 (1): 51. arXiv:1204.2572. Bibcode:2012A&ARv..20...51V. doi:10.1007/s00159-012-0051-2. S2CID 119273474.
  13. "CD-38 13036B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-16.
  14. "CD-38 13036C". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-16.
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