1 Scorpii
Star in the constellation Scorpius
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1 Scorpii, or b Scorpii, is a single[9] star in the southern zodiac constellation of Scorpius. It has an apparent magnitude of 4.63,[1] which is bright enough to be faintly visible to the naked eye on a dark night. The star shows an annual parallax shift of 6.59 mas from Earth's orbit, which equates to a distance of roughly 490 light years. It is a probable (89% chance) member of the Sco OB2 moving group.[10][9]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Scorpius[1] |
| Right ascension | 15h 50m 58.74452s[2] |
| Declination | −25° 45′ 04.6649″[2] |
| Apparent magnitude (V) | 4.63[1] |
| Characteristics | |
| Spectral type | B1.5 Vn[3] |
| B−V color index | −0.072±0.003[1] |
| Astrometry | |
| Radial velocity (Rv) | −3.0±4.7[4] km/s |
| Proper motion (μ) | RA: −14.20[2] mas/yr Dec.: −25.12[2] mas/yr |
| Parallax (π) | 6.59±0.27 mas[2] |
| Distance | 490 ± 20 ly (152 ± 6 pc) |
| Absolute magnitude (MV) | −1.27[1] |
| Details | |
| Mass | 8.3±0.2[5] M☉ |
| Radius | 3.7[6] R☉ |
| Luminosity | 3,890[6] L☉ |
| Temperature | 24,000[6] K |
| Rotational velocity (v sin i) | 310[7] km/s |
| Age | 10.3±5.3[5] Myr |
| Other designations | |
| b Sco, 1 Sco, CD−25°11131, HD 141637, HIP 77635, HR 5885, SAO 183854[8] | |
| Database references | |
| SIMBAD | data |
This is a B-type main-sequence star with a stellar classification of B1.5 Vn,[3] where the 'n' suffix indicates "nebulous" absorption lines being induced by rapid rotation. It has a projected rotational velocity of 310 km/s, which is giving the star an oblate shape with an equatorial bulge that is 13% wider than the polar radius.[7] There is some weak evidence that this is a Be star with a gaseous disk that is being viewed edge-on.[11]
1 Scorpii is a young star at around 10[5] million years old, with 8.3[5] times the mass of the Sun and 3.7 times the Sun's radius.[6] The star is radiating 3,890 times the Sun's luminosity from its photosphere at an effective temperature of about 24,000 K.[6]