Kappa Scorpii
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| Observation data Epoch J2000 |
|
|---|---|
| Constellation (pronunciation) |
Scorpius |
| Right ascension | 17h 42m 29.3s |
| Declination | -39° 01′ 48″ |
| Apparent magnitude (V) | 2.39 |
| Characteristics | |
| Spectral type | B1.5 III |
| U-B color index | -0.89 |
| B-V color index | -0.22 |
| Variable type | β Cephei |
| Astrometry | |
| Radial velocity (Rv) | -14 km/s |
| Proper motion (μ) | RA: -6.49 mas/yr Dec.: -25.55 mas/yr |
| Parallax (π) | 7.03 ± 0.73 mas |
| Distance | approx. 460 ly (approx. 140 pc) |
| Absolute magnitude (MV) | -3.38 |
| Other designations | |
Kappa Scorpii (κ Sco / κ Scorpii) is a star in the constellation Scorpius. It also has the traditional name Girtab.
The name Girtab is actually (or perhaps originally) applied to an asterism comprising this star, Lambda Scorpii, Upsilon Scorpii, and Iota Scorpii.
This star is a spectroscopic binary, and the primary is also a Beta Cephei variable-type pulsating star. Spectroscopic measurements have given an orbital period of 195 days. The pulsations have a primary component of 4.80 hours and a secondary period of 4.93 hours.
[edit] References
- K. Uytterhoeven et al, 2005, "Disentangling component spectra of kappa Scorpii, a spectroscopic binary with a pulsating primary," Astronomy and Astrophysics, Volume 432, Issue 3.
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