Theta Normae

θ Normae, Latinised as Theta Normae, is a binary star system in the constellation Norma. It has an apparent visual magnitude of 5.13^[2] and is visible to the naked eye as a faint, blue-white-hued point of light. Based upon an annual parallax shift of 9.27 mas as seen from Earth,^[5] this system is located about 352 light-years from the Sun. At that distance, the visual magnitude of these stars is diminished by an extinction of 0.45 due to interstellar dust.^[12]

Theta Normae

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Norma
Right ascension	16h 15m 15.31794s[1]
Declination	−47° 22′ 19.2710″[1]
Apparent magnitude (V)	5.13[2]
Characteristics
Spectral type	B8 V[3]
B−V color index	−0.12[2]
Astrometry
Radial velocity (Rv)	+1.4±4.2[4] km/s
Proper motion (μ)	RA: −34.771 mas/yr Dec.: −45.813 mas/yr
Parallax (π)	9.2718±0.1692 mas[5]
Distance	352 ± 6 ly (108 ± 2 pc)
Absolute magnitude (MV)	−0.23[6]
Details
Mass	3.6[7] M☉
Radius	3.05[8] R☉
Luminosity	184[9] L☉
Surface gravity (log g)	4.5[7] cgs
Temperature	12,341[9] K
Rotational velocity (v sin i)	251[10] km/s
Age	17[7] Myr
Other designations
θ Nor, CPD−47° 10611, HD 145842, HIP 79653, HR 6045, SAO 226600[11]
Database references
SIMBAD	data

Chini et al. (2012) identified this as a single-lined spectroscopic binary system.^[13] The visible component is a B-type main-sequence star with a stellar classification of B8 V.^[3] It is about 17^[7] million tears old and is spinning rapidly with a projected rotational velocity of 251 km/s.^[10] The star has 3.6^[7] times the mass of the Sun and 3.05^[8] times the Sun's radius. It is radiating about 184 times the Sun's luminosity from its photosphere at an effective temperature of 12,341 K.^[9] This system displays an infrared excess, suggesting a debris disk is orbiting at a mean radius of 21.8 AU with a temperature of 220 K.^[8]