V915 Scorpii
 Position of V915 Scorpii (circled) |
|
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Scorpius |
| Right ascension | 17h 14m 27.65446s[1] |
| Declination | −39° 45′ 59.9377″[1] |
| Apparent magnitude (V) | +6.22 - 6.64[2] |
| Characteristics | |
| Spectral type | K0Ia-0[3] |
| U−B color index | 2.48[4] |
| B−V color index | 2.25[4] |
| Variable type | Unknown[2] |
| Astrometry | |
| Radial velocity (Rv) | 46.00[5] km/s |
| Proper motion (μ) | RA: −1,42[1] mas/yr Dec.: −1.47[1] mas/yr |
| Parallax (π) | −0.69 ± 0.77[1] mas |
| Distance | 1,800[6] - 7,300[7] pc |
| Absolute magnitude (MV) | −9.0[8] |
| Details | |
| Luminosity | 350,000[8] L☉ |
| Surface gravity (log g) | 0.0[9] cgs |
| Temperature | 5,100[10] K |
| Metallicity [Fe/H] | +0.55[9] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
V915 Scorpii (HR 6392, HD 155603) is an orange hypergiant star in the constellation Scorpius.
Surroundings
V915 Scorpii is surrounded by the sparse OB association Moffat 2.[6] It is also surrounded by an envelope of dust and gas, producing a significant infrared excess.[10]
V915 Sco has been classified as a triple star. 15" away is the Wolf-Rayet star WR 85, one of the most luminous stars known, but still four magnitudes fainter than V915 Sco.[11] Component C is a 10th magnitude K class star 17" away.[12] There is also a 14th magnitude star 22" away. Photometry and space motions suggest that only V915 Sco and WR 85 lie at the same distance, while the other two stars are foreground objects. Assumptions about the brightness of each star suggest a distance of 2,600 parsecs, and a projected separation of 0.2 pc.[7]
Four arc minutes distant are two other assumed members of the association, a 10th magnitude B0 giant and an 11th magnitude OB star. Fitting the association members to a main sequence gives a highly uncertain distance of 1.8 kpc.[6] A kinematical distance has been calculated for the bubble around WR 85 at 2.8 kpc.[13] The distance to V915 Scorpii derived assuming minimal interstellar extinction is 7,300 pc.[10] However, the star is considerably reddened and this results in a distance of 2,630 pc.[7] Analysis of WR 85 as a luminous hydrogen-rich star gives a distance of 6,600 pc.[11]
Variable
V915 Scorpii is variable over nearly half a magnitude, but the nature of the variations is not known.[2][14] Any period associated with the variation is longer than 600 days.[15]
Properties
The distance to V915 Sco is highly uncertain, and it has hardly been observed in the last 20 years, but its absolute magnitude is consistently determined between −8 and −9, making it an extremely luminous supergiant.[6][8][10] The spectral type was assigned as G5Ia in 1954,[16] G5Ia-0 in 1973,[17] G8Ia in 1977,[6] K0Ia in 1982,[18] and K0Ia-0 in 1989.[3]
References
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- ↑ 10.0 10.1 10.2 10.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 11.0 11.1 Lua error in package.lua at line 80: module 'strict' not found.
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