Beta Scorpii
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| Observation data Epoch J2000.0 |
|
|---|---|
| Constellation | Scorpius |
| Right ascension | 16h 05m 26.7s |
| Declination | -19° 48' 20" |
| Apparent magnitude (V) | β¹; 2.56 β²; 4.90 |
| Spectral Characteristics | |
| Spectral type | B0.5V+B2V |
| U-B color index | -0.07 |
| B-V color index | -0.08 |
| Variable type | ? |
| Astrometry | |
| Radial velocity (Rv) | -1 km/s |
| Proper motion (μ) | RA: -6.75 mas/yr Dec.: -24.89 mas/yr |
| Parallax (π) | 6.15 ± 1.15 mas |
| Distance | 530 ly (163 pc) |
| Absolute magnitude (MV) | β¹; -3.50 β²; -1.16 |
| Physical Characteristics | |
| Mass | ? M☉ |
| Radius | 19 R☉ |
| Luminosity | 3000 L☉ |
| Temperature | β¹; 27 000 K β²; 22 000 K |
| Metallicity | ? |
| Rotation | ~130 km/s. |
| Age | ? years |
| Other designations | |
Beta Scorpii (β Sco / β Scorpii) is a star system in the constellation Scorpius. It also has the traditional names Acrab, Akrab or El Acrab(Arabic:العقرب), as well as Graffias, a name it shares with Xi Scorpii. It is known as 房宿四 (the Fourth Star of the Room) in Chinese.
Observed through a small telescope, Beta Scorpii is found to be a binary star with a separation between the two components of 14 arcseconds, putting them at least 2200 Astronomical Units (AU) apart. They are both hot, B-class stars at least 10 times as massive as our own Sun, and will have short lives. Both are expected to end their stellar evolution in massive supernovae.
Beta-1 Scorpii, the brighter of the pair, has another companion 0.5 arcseconds, or about 80 AU, distant. Furthermore, both Beta-1 Scorpii and Beta-2 Scorpii, the two hot, B-class stars, are themselves thought to be spectroscopic binaries, bringing the total number of stars in the system to five.
Because it is close to the ecliptic, Beta Scorpii can be occulted by the Moon and, very rarely, by planets. The last occultation by a planet took place on 13 May 1971, by Jupiter.
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