| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Scorpius |
| Right ascension | 17h11m 17.01945s[1] |
| Declination | −32° 19′ 30.7140″[1] |
| Apparent magnitude (V) | 6.5 - 9.6[2] |
| Characteristics | |
| Spectral type | M4-5 Ia-Iab[3] |
| B−V color index | +2.57[4] |
| Variable type | SRc[3] |
| Astrometry | |
| Radial velocity (Rv) | −13.40±2.4[5] km/s |
| Proper motion (μ) | RA: −2.322±0.115[1] mas/yr Dec.: −2.610±0.068[1] mas/yr |
| Parallax (π) | 0.5632 ± 0.0799 mas[1] |
| Distance | 7,400±620 ly (2,260±190[6] pc) |
| Absolute magnitude (MV) | −5.8[7] |
| Details | |
| Mass | 20[8] M☉ |
| Radius | 1,411±124[4] R☉ |
| Luminosity | 329,000±86,000[4] L☉ |
| Surface gravity (log g) | −0.5[4] cgs |
| Temperature | 3,682[4] K |
| Other designations | |
AH Sco, AN 223.1907, GSC 07365-00527, HD 155161, HIP 84071, CD−32°12429, 2MASS J17111702-3219308, IRC−30282, IRAS 17080-3215, RAFGL 1927, AAVSO 1704-32 | |
| Database references | |
| SIMBAD | data |
AH Scorpii (abbreviated to AH Sco) is a red supergiant variable star located in the constellation Scorpius. It is one of the largest stars known by radius and is also one of the most luminous red supergiant stars in the Milky Way.
The distance of AH Scorpii is considered to be uncertain. VLBI measurements of the masers have provided an accurate distance of 2,260 parsecs based on observation of SiO, H2O, and OH masers in its oxygen-rich circumstellar material. The masers were observed to be approaching the star at 13 km/s, indicating overall contraction at around phase 0.55 of the visual variations.[6]
AH Scorpii is a dust-enshrouded red supergiant[10] and is classified as a semiregular variable star with a main period of 714 days. The total visual magnitude range is 6.5 - 9.6.[2] No long secondary periods have been detected.[11] Modelling of AH Scorpii near maximum light has determined an effective temperature of 3,682±190 K and a luminosity of 330,000±86,000 L☉. A radius of 1,411±124 R☉ was determined from an angular diameterof5.81±0.15 mas and the given distance of 2.26±0.19 kpc.[4] Its angular diameter was re-measured at 5.05±0.5 mas in 2023.[12]
