Theta Circini

Theta Circini
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Circinus
Right ascension	14^h 56^m 43.98738^s ^[1]
Declination	−62° 46 51.6579′ ^[1]
Spectral type	B4Vnpe ^[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.

References

1 2 3 4 5 SIMBAD, (accessed 15 January 2013)

Circinus constellation

Stars (list)

Bayer	α β γ δ ε ζ η θ

Variable	T AX BP BU BW BX CO

HR	5194 5218 5242 5253 5293 5295 5320 5379 5382 5391 5408 5443 5465 5482 5486 5515 5546 5623 5632 5645 5661 5680 5700

HD	129092 129445 130021 130942 131491 133557 134657

Other	Circinus X-1 PSR B1451-68 PSR B1509-58 WR 66 WR 70

Star clusters

Open	NGC 5288 NGC 5359 NGC 5715 NGC 5823

Nebulae

Planetary	NGC 5315

SNR	G315.4-2.3

Pulsar wind	MSH 15-52

Galaxies

Circinus Galaxy

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