13 Scorpii
Star in the constellation Scorpius
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13 Scorpii, also known by its Bayer designation c2 Scorpii, is a binary star in the constellation Scorpius. Its apparent magnitude is 4.57,[3] meaning it can be faintly seen with the naked eye. Based on parallax estimates made by the Hipparcos spacecraft, the system is located about 480 light-years (147 parsecs) away.[2] It is located within the Upper Scorpius subgroup of the Scorpius–Centaurus association.[7]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Scorpius[1] |
| Right ascension | 16h 12m 18.20490s[2] |
| Declination | −27° 55′ 34.9457″[2] |
| Apparent magnitude (V) | +4.568[3] |
| Characteristics | |
| Spectral type | B2V[4] |
| U−B color index | −0.74[5] |
| B−V color index | −0.16[5] |
| Astrometry | |
| Radial velocity (Rv) | 0 ± 5[6] km/s |
| Proper motion (μ) | RA: −10.38[2] mas/yr Dec.: −23.94[2] mas/yr |
| Parallax (π) | 6.81±0.16 mas[2] |
| Distance | 480 ± 10 ly (147 ± 3 pc) |
| Absolute magnitude (MV) | −1.25[1] |
| Orbit[4] | |
| Period (P) | 5.7805 d |
| Eccentricity (e) | 0.19 |
| Periastron epoch (T) | JD 2443298.40 |
| Argument of periastron (ω) (secondary) | 115° |
| Semi-amplitude (K1) (primary) | 31.5 km/s |
| Details | |
| 13 Sco A | |
| Mass | 7.80[7] M☉ |
| Luminosity | 3020[8] L☉ |
| Temperature | 24000[8] K |
| Rotational velocity (v sin i) | 165[9] km/s |
| Age | 11[7] Myr |
| 13 Sco B | |
| Mass | 1.12[7] M☉ |
| Other designations | |
| c2 Sco, 13 Sco, CD−27°10841, HD 145482, HIP 79404, HR 6028, SAO 184221[10] | |
| Database references | |
| SIMBAD | data |
13 Scorpii is a spectroscopic binary, meaning the two stars are too close to be individually resolved, but periodic Doppler shifts in the star's spectrum indicate there must be orbital motion. In this case, light from only one of its stars can be detected and it is a double-lined spectroscopic binary.[4] The two have an orbital period of 5.7805 days and an eccentricity of 0.19.[4] The primary star, at 11 million years old,[7] is a B-type main-sequence star with a spectral type of B2V.[4] While the primary's mass is estimated to be about 7.8 M☉, its companion is thought to have a mass of 1.12 M☉.[7]