Zeta1 Scorpii
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Scorpius |
| Right ascension | 16h 53m 59.72713s |
| Declination | −42° 21′ 43.3073″ |
| Apparent magnitude (V) | 4.705 (4.66 to 4.86) |
| Characteristics | |
| Spectral type | B1.5 Iae |
| U−B color index | −0.567 |
| B−V color index | +0.480 |
| Variable type | Luminous blue variable |
| Astrometry | |
| Radial velocity (Rv) | −26.0 km/s |
| Proper motion (μ) | RA: −0.094 mas/yr Dec.: −3.368 mas/yr |
| Parallax (π) | 0.5855±0.1176 mas |
| Distance | approx. 6,000 ly (approx. 1,700 pc) |
| Absolute magnitude (MV) | −8.5 |
| Details | |
| Mass | 36 to 53 M☉ |
| Radius | 103 to 125.5 R☉ |
| Luminosity (bolometric) | 8.5×105 to 1.26×106 L☉ |
| Surface gravity (log g) | 1.7 cgs |
| Temperature | 17,200 K |
| Rotational velocity (v sin i) | 60 km/s |
| Age | 6.5 ± 0.1 Myr |
| Other designations | |
| ζ1 Sco, CD−42 11633, CPD−42 7545, GC 22730, HD 152236, HIP 82671, HR 6262, PPM 322342, SAO 227375. | |
| Database references | |
| SIMBAD | data |
Zeta1 Scorpii (Zeta1 Sco, ζ1 Scorpii, ζ1 Sco) is a B-type hypergiant star in the constellation of Scorpius. It has an apparent visual magnitude which varies between 4.66 and 4.86. It is a member of the Scorpius OB1 association, and potentially of the open star cluster NGC 6231, also known as the "Northern jewel box" cluster.
ζ1 Scorpii is a luminous blue variable according to its luminosity and spectral appearance, yet is has not shown the characteristic types of variability, hence is classified as a dormant LBV. Around 36 times as massive as the Sun, it is one of the most luminous stars known in the Galaxy, with an estimated bolometric luminosity between 850,000 and 1.3 million times that of the Sun and a radius 103 to 126 times that of the Sun. The stellar wind from this supergiant is expelling matter from the star at the rate of 1.55 × 10−6 solar masses per year, or roughly the equivalent to the Sun's mass every 640,000 years.
ζ1 Scorpii forms a naked eye double with ζ2 Scorpii, but the stars are merely coincidentally near in the line of sight from Earth. ζ2 is a mere 135 light-years distant and much less luminous in real terms. ζ1 Scorpii can also be distinguished from ζ2, due to the latter's orange hue especially in long-exposure photographs.