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Theta Arae
	The location of θ Arae (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Ara
Right ascension	18h 06m 37.87129s
Declination	–50° 05′ 29.3125″
Apparent magnitude (V)	+3.67
Characteristics
Spectral type	B2 Ib
U−B color index	–0.870
B−V color index	–0.109
Astrometry
Radial velocity (Rv)	+3.4 km/s
Proper motion (μ)	RA: –8.27 mas/yr ; Dec.: –8.70 mas/yr
Parallax (π)	4.01 ± 0.15 mas
Distance	810 ± 30 ly ; (249 ± 9 pc)
Absolute magnitude (MV)	−3.33
Details
Mass	8.9 ± 0.1 M☉
Radius	20.1 R☉
Luminosity	3,450 L☉
Surface gravity (log g)	2.70 cgs
Temperature	17,231 ± 231 K
Rotational velocity (v sin i)	95 km/s
Age	28.2 ± 4.7 Myr
Other designations
	θ Ara, CD−50° 11720, FK5 1471, HD 165024, HIP 88714, HR 6743, SAO 245242.
Database references
SIMBAD	data

Theta Arae, Latinized from θ Arae, is the Bayer designation for a star in the constellation Ara. It has an apparent visual magnitude of +3.67,^[2] which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 4.01 mas,^[1] Theta Arae is 810 light-years (250 parsecs) distant from the Earth.

This is a supergiant star with a stellar classification of B2 Ib.^[3] It has nearly nine^[6] times the mass of the Sun and is over 20^[7] times the Sun's radius. The outer atmosphere of this star has an effective temperature of 17,231 K;^[7] much hotter than the surface of the Sun. At this heat, the star shines with the characteristic blue-white hue of a B-type star.^[11]

References

^ ^a ^b ^c ^d ^e ^f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
^ ^a ^b ^c ^d Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A photometric investigation of the Scorpio-Centaurus association", Astrophysical Journal Supplement, 15: 459, Bibcode:1968ApJS...15..459G, doi:10.1086/190168.
^ ^a ^b Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
^ Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg, 35 (35), Astronomisches Rechen-Institut Heidelberg: 1, Bibcode:1999VeARI..35....1W.
^ ^a ^b 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.
^ ^a ^b ^c Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x, S2CID 118629873.
^ ^a ^b ^c ^d Underhill, A. B.; et al. (November 1979), "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars", Monthly Notices of the Royal Astronomical Society, 189 (3): 601–605, Bibcode:1979MNRAS.189..601U, doi:10.1093/mnras/189.3.601.
^ Fraser, M.; et al. (May 2010), "Atmospheric parameters and rotational velocities for a sample of Galactic B-type supergiants", Monthly Notices of the Royal Astronomical Society, 404 (3): 1306–1320, arXiv:1001.3337, Bibcode:2010MNRAS.404.1306F, doi:10.1111/j.1365-2966.2010.16392.x, S2CID 118674151.
^ Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1): 1, Bibcode:1970CoAsi.239....1B.
^ "* tet Ara". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2010-07-30.{{cite web}}: CS1 maint: postscript (link)
^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2013-12-03, retrieved 2012-01-16