Theta Normae
Star in the constellation Norma
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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]
| 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 |
| Rotation | 1.144[10] days |
| Rotational velocity (v sin i) | 109[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, with 3.6 times the mass of the Sun[7] and 3.05 times the Sun's radius.[8] It is radiating about 184 times the Sun's luminosity from its photosphere at an effective temperature of 12,341 K.[9] It is a mercury-manganese star, a B to A-type star with overabundances of the chemical elements mercury and manganese. It takes 1.144 days to fully rotate and has a projected rotational velocity of 109 km/s, unusually fast of a HgMn star.[10]
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]