2 Scorpii, a blue-white main-sequence star in Scorpius
2 Scorpii is a blue-white main-sequence star in the constellation Scorpius. At 503 light years away, it shines at an apparent visual magnitude of 4.59.
2 Scorpii (HIP 77840)
2 Scorpii is a blue-white main-sequence star in the constellation Scorpius. At 503 light years away, it shines at an apparent visual magnitude of 4.59. It is moving through the Galaxy at a speed of 23.4 km/s relative to the Sun.
Sky position: RA 15h 53.6m, Dec -25° 19.6'
Common designations: 2 Scorpii, HR 5904, HD 142114, HIP 77840
2 Scorpii has the spectral type B2.5Vn. B-type stars are hot (about 10,000 to 30,000 K), luminous and blue-white. They are massive, short-lived stars, typically only tens of millions of years old, and are common in young clusters and OB associations. Its luminosity class V means it is a main-sequence (dwarf) star, still fusing hydrogen into helium in its core like the Sun.
How to find 2 Scorpii in the sky
2 Scorpii lies in Scorpius. With a declination of -25° 19.6', it is visible from the entire Southern Hemisphere and from the Northern Hemisphere up to about latitude 65° N. It is bright enough to see with the naked eye under dark skies. It is highest in the sky at local midnight around June, which makes the weeks around that month the best time to observe it.
Tabulated data for 2 Scorpii
Astrometry and spectroscopy
| Right Ascension (J2000) | 238.40299500° (15h 53.6m) |
| Declination (J2000) | -25.32714131° (-25° 19.6') |
| Galactic Longitude | 346.87682228° |
| Galactic Latitude | 21.61337981° |
| Proper motion RA | -15.12 mas/yr |
| Proper motion Dec | -25.18 mas/yr |
| Parallax | 6.49 ± 0.51 mas |
| Spectral Type | B2.5Vn |
| Radial Velocity | -9.30 km/s |
Photometry
| Band | Magnitude | Abs. Mag. |
|---|---|---|
| U | 3.86 | -2.08 |
| B | 4.52 | -1.42 |
| V | 4.59 | -1.35 |
| J | 4.74 | -1.20 |
| H | 4.81 | -1.12 |
| K | 4.79 | -1.15 |
Colour index B-V: -0.07
Derivations
- Heliocentric distance: 154.08 pc (503 light years) (7.9% margin of error)
- Absolute visual magnitude: -1.35
- Transverse velocity: 21.5 km/s
- Space velocity relative to the Sun: 23.4 km/s
- Galactic position (X, Y, Z): 139.5 pc, -32.5 pc, 56.8 pc
- Galactic velocity (U, V, W): -11.0 km/s, -18.6 km/s, -8.9 km/s
Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.