Theta1 Orionis C

Theta¹ Orionis C
	; Theta1 Orionis C and companions.
Observation data; Epoch J2000 Equinox J2000
Constellation	Orion
Right ascension	05h 35m 16.5s
Declination	−05° 23′ 24″
Apparent magnitude (V)	5.13
Characteristics
Spectral type	O6pe V
U−B color index	−0.88
B−V color index	+0.02
Variable type	?
Astrometry
Radial velocity (Rv)	+28 km/s
Proper motion (μ)	RA: −0.92 mas/yr ; Dec.: 0.13 mas/yr
Parallax (π)	−1.85 ± 2.12 mas
Distance	1,500 ly ; (460 pc)
Absolute magnitude (MV)	−3.2
Details
Mass	40 M☉
Radius	8 R☉
Luminosity	251,000 L☉
Temperature	45,500 K
Metallicity	?
Rotation	~112 km/s
Age	1.2 × 106 years
Other designations
	41 Ori C, HR 1895, HD 37022, SAO 132314, V1016 Ori.
Database references
SIMBAD	data

Theta¹ Orionis C is a member of the Trapezium open cluster that lies within the Orion Nebula. The star C is the most massive of the four bright stars at the heart of the cluster. It is an O class blue main sequence star and has the highest surface temperature of any star visible to the naked eye; it is one of the most luminous stars known, with an estimated absolute magnitude in visible wavelengths of about −3.2. Its high luminosity and large distance (about 1,500 light years) give it an apparent visible magnitude of 5.1.

This star is responsible for generating most of the ultraviolet light that is slowly ionizing (and perhaps photoevaporating) the Orion Nebula. This UV light is also the primary cause of the glow that illuminates the Orion Nebula. The star emits a powerful stellar wind that is a hundred thousand times stronger than the Sun's, and the outpouring gas moves at 1,000 km/s.

Infrared observations of Theta¹ Orionis C have shown that it is actually a close binary system. It also displays optical variability and is a variable X-ray source.

It is expected that this star will expand into a red supergiant and end its life as a supernova within a few million years from now.

References

Gagne, Marc (1997). "Periodic X-Ray Emission from the O7 V Star θ¹ Orionis C". Astrophysical Journal Letters. 478 (2): L87 – L90. Bibcode:1997ApJ...478L..87G. doi:10.1086/310558. {{cite journal}}: Cite has empty unknown parameter: |month= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
Walborn, N. R. (1981). "Systematic variations in the spectrum of Theta-1 Orionis C". Astrophysical Journal. 243 (1): L37 – L39. Bibcode:1981ApJ...243L..37W. doi:10.1086/183438. {{cite journal}}: Cite has empty unknown parameters: |month= and |coauthors= (help)

External links