Epsilon Trianguli Australis

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Epsilon Trianguli Australis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Triangulum Australe
Right ascension 15h 36m 43.22223s[1]
Declination −66° 19′ 01.3334″[1]
Apparent magnitude (V) +4.11[2]
Spectral type K0 III[3]
U−B color index +1.16[2]
B−V color index +1.17[2]
Radial velocity (Rv) −15.5±2.7[4] km/s
Proper motion (μ) RA: +24.35[1] mas/yr
Dec.: −54.47[1] mas/yr
Parallax (π) 16.17 ± 0.18[1] mas
Distance 202 ± 2 ly
(61.8 ± 0.7 pc)
Absolute bolometric
Mass 1-2 M
Radius 16.2±0.2 R
Luminosity 91 L
Surface gravity (log g) 2.20+0.14
Temperature 4,436 K
Other designations
ε TrA, CPD−65° 3102, FK5 574, HD 138538, HIP 76440, HR 5771, SAO 253226, WDS J15367-6619[6]
Database references

Epsilon Trianguli Australis (ε Trianguli Australis) is a star in the southern circumpolar constellation of Triangulum Australe. It is visible to the naked eye with an apparent visual magnitude of +4.11.[2] Based upon an annual parallax shift of 16.17 mas as seen from the Earth,[1] the star is located about 340 light years from the Sun.

This is an evolved K-type giant star with a stellar classification of K0 III.[3] It has around 1−2 times the mass of the Sun and has expanded to 16.2 times the Sun's radius. The star is radiating 91 times the Sun's luminosity from its photosphere at an effective temperature of 5,039 K.[5] It has a magnitude 9.36 optical companion at an angular separation of 81.9 arc seconds along a position angle of 220°, as of 2010.[7]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J. 
  3. ^ a b Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4, Bibcode:1962MtSOM...4....1B. 
  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, Bibcode:2012A&A...546A..61D, arXiv:1208.3048Freely accessible, doi:10.1051/0004-6361/201219219, A61. 
  5. ^ a b c Cruzalèbes, P.; et al. (September 2013), "Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI/AMBER", Monthly Notices of the Royal Astronomical Society, 434 (1): 437–450, Bibcode:2013MNRAS.434..437C, arXiv:1306.3288Freely accessible, doi:10.1093/mnras/stt1037. 
  6. ^ "eps TrA". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-30. 
  7. ^ Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22  "Optical pair, based on study of relative motion of the components using the method of apparent motion parameters. —DUN 188"