HD 168607
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Sagittarius |
| Right ascension | 18h 21m 14.889s |
| Declination | −16° 22′ 31.76″ |
| Apparent magnitude (V) | 8.28 (var) |
| Characteristics | |
| Spectral type | B9Ia+ |
| U−B color index | 0.41 |
| B−V color index | 1.54 |
| J−K color index | 1.06 |
| Variable type | LBV |
| Astrometry | |
| Radial velocity (Rv) | -30 km/s |
| Proper motion (μ) |
RA: -0.27 mas/yr Dec.: -1.01 mas/yr |
| Parallax (π) | 1.85 ± 1.29mas |
| Distance | approx. 2,000 ly (approx. 500 pc) |
| Absolute magnitude (MV) | −8.4 |
| Details | |
| Luminosity | 240,000 L☉ |
| Surface gravity (log g) | 1.0 cgs |
| Temperature | 9,300 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 168607 (V4029 Sgr) is a blue hypergiant and luminous blue variable (LBV) star located in the constellation of Sagittarius, easy to see with amateur telescopes. It forms a pair with HD 168625, also a blue hypergiant and possible luminous blue variable, that can be seen at the south-east of M17, the Omega Nebula.
HD 168607 is usually assumed to be at the same distance of the Omega Nebula (2.2 kiloparsecs, 7,200 light years, from the Sun) and may be physically associated with HD 168625. Assuming this distance is correct, this star is 240,000 times brighter than the Sun with a surface temperature of 9300 K. Its apparent magnitude has a variation of 0.25-0.30 m. with a period of 64 days, but no outburst has been observed. Unlike its neighbour HD 168625, no nebula has been found around this star.
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