Eta Trianguli Australis

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η Trianguli Australis
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Triangulum Australe
Right ascension 16h 41m 23.3s
Declination −68° 17' 46"
Apparent magnitude (V) +5.89
Distance 690 ± 95 ly
(210 ± 30 pc)
Spectral type B7IVe
Other designations
HR 6172, HD 149671,
CP-68 2789, HIP 81710,
SAO 253649, GC 22379

Eta Trianguli Australis (η TrA, η Trianguli Australis) is a star in the constellation Triangulum Australe. It is sometimes given a superscript: η¹ Trianguli Australis, though it is the only star that is commonly referred to by this Bayer designation.

Eta Trianguli Australis is a blue-white B-type subgiant with an apparent magnitude of +5.89. It is approximately 661 light years (203 parsecs) from Earth.[1] Lacaille named a close by star as Eta as well, which was inconsistently followed by Francis Baily, who used the name for the brighter or both stars in two different publications. Despite their faintness, Gould upheld their Bayer designation as they were closer than 25 degrees to the south celestial pole. The second Eta is now designated as HD 150550.[2] It is a variable star of average magnitude 6.53 and spectral type A1III.[3]


  1. ^ "HR 6172 -- Be Star". SIMBAD. Retrieved 4 October 2012. 
  2. ^ Wagman, Morton (2003). Lost Stars: Lost, Missing and Troublesome Stars from the Catalogues of Johannes Bayer, Nicholas Louis de Lacaille, John Flamsteed, and Sundry Others. Blacksburg, VA: The McDonald & Woodward Publishing Company. pp. 303–04. ISBN 978-0-939923-78-6. 
  3. ^ "HD 150550 -- Pulsating variable Star". SIMBAD. Retrieved 4 October 2012.