| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Scorpius[1] |
| Right ascension | 15h 53m 36.71880s[2] |
| Declination | −25° 19′ 37.7087″[2] |
| Apparent magnitude (V) | 4.69 + 6.98[3] |
| Characteristics | |
| Spectral type | B2.5 Vn[4] |
| B−Vcolor index | −0.11/+0.07[3] |
| Astrometry | |
| Radial velocity (Rv) | −9.3±1.6[5] km/s |
| Proper motion (μ) | RA: −15.12[2]mas/yr Dec.: −25.18[2]mas/yr |
| Parallax (π) | 6.49±0.51 mas[2] |
| Distance | 500 ± 40 ly (150 ± 10 pc) |
| Absolute magnitude (MV) | −1.33[1] |
| Details | |
| 2 Sco A | |
| Mass | 6.9±0.1[6] M☉ |
| Luminosity | 457.40[1] L☉ |
| Temperature | 20,350[7] K |
| Rotational velocity (v sin i) | 320[8] km/s |
| Age | 30.4±4.6[6] Myr |
| Other designations | |
| A Sco,2 Sco,CD−24°12352,HD 142114,HIP 77840,HR 5904,SAO 183896,WDS J15536-2520[9] | |
| Database references | |
| SIMBAD | data |
2 Scorpii (A Scorpii) is adouble star in the southernzodiacconstellation ofScorpius. The brighter component has anapparent visual magnitude of 4.69, which is bright enough to be visible to the naked eye, while the fainter star is of magnitude 6.98.[3] The distance to this pair can be estimated from the annualparallax shift of6.49±0.51 mas,[2] which places it roughly 500 light years away. It has apeculiar velocity of16.5±2.4 km/s and is moving closer to the Sun with a heliocentricradial velocity of about −9 km/s,[5] which will bring it to aperihelion distance of 450 ly (139 pc) in about 2.9 million years.[1] This is a probable (73% chance) member of the Lower Centaurus–Crux group of the nearbyScorpius–Centaurus association (Sco OB2), or else (27% chance) it is a member of theGould's Belt.[10]
With high likelihood (>95%), this is abinary star system. As of 2014, the pair had anangular separation of2.061″±0.001″ along aposition angle of268.28°±0.02°.[7] The brighter member, component A, is aB-type main-sequence star with astellar classification of B2.5 Vn.[4] The 'n' suffix indicates broad (nebulous)absorption lines due to rapid rotation. It is spinning with aprojected rotational velocity of 320 km/s, giving the star anoblate shape with anequatorial bulge that is 15% larger than the polar radius.[8] Roughly 30[6] million years old, it has an estimated 6.9[6] times themass of the Sun and is radiating 457[1] times theSun's luminosity from itsphotosphere at aneffective temperature of 20,350 K.[7]
