Theta Circini

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Theta Circini
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Circinus
Right ascension 14h 56m 43.98738s [1]
Declination −62° 46 51.6579′ [1]

Theta Circini (t Cir), is a star located in the constellation Circinus. Theta Circini is also known as HR 5551, and HD 131492. The star is a spectroscopic binary. The system is located at Right Ascension 14h 56m 44s and Declination -62 deg 46 arcmin 51 arcsec.[1] The system has a combined apparent visual magnitude of +5.11,[1] and is located 255 parsecs (833 light years) from the Sun.

Theta Circini A and B are both B4V dwarf stars with effective temperatures of 15000 Kelvin. Each has an apparent visual magnitude +5.9, and an absolute magnitude of -1.96 and a mass of 3.2 solar masses. The components are separated by 0.1 arcsec.

The system is notable for having three peculiar characteristics: its spectra, brightness variations, and stellar pulsations. The star is classified as an H-Alpha variable for its spectral variations. It is classified (due to the orbital characteristics), as a Gamma Cassiopeia variable. Finally, it is considered to be a BE Lacertae variable star, exhibiting massive pulsations.


  1. ^ a b c d e SIMBAD, [1] (accessed 15 January 2013)