HD 149382
Star in the Ophiuchus constellation
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HD 149382 is a hot subdwarf star in the constellation of Ophiuchus with an apparent visual magnitude of 8.943.[2] This is too faint to be seen with the naked eye even under ideal conditions, although it can be viewed with a small telescope.[8] Based upon parallax measurements, this star is located at a distance of about 246 light-years (75.5 parsecs) from the Earth.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 16h 34m 23.33337s[1] |
| Declination | −04° 00′ 52.0301″[1] |
| Apparent magnitude (V) | 8.943[2] |
| Characteristics | |
| Spectral type | B5 VI[3] |
| U−B color index | −1.143[2] |
| B−V color index | −0.282[2] |
| V−R color index | −0.127[2] |
| R−I color index | −0.135[2] |
| Astrometry | |
| Radial velocity (Rv) | +3[4] km/s |
| Proper motion (μ) | RA: −6.234[1] mas/yr Dec.: −5.780[1] mas/yr |
| Parallax (π) | 13.2407±0.0567 mas[1] |
| Distance | 246 ± 1 ly (75.5 ± 0.3 pc) |
| Details | |
| Mass | 0.29 – 0.53[5] M☉ |
| Radius | 0.143[6] R☉ |
| Luminosity | 25.2[6] L☉ |
| Surface gravity (log g) | 5.80±0.05[5] cgs |
| Temperature | 35,500±500[5] K |
| Metallicity [Fe/H] | −1.30[3] dex |
| Rotational velocity (v sin i) | 4.9±1.4[5] km/s |
| Other designations | |
| BD−03°3967, HD 149382, HIP 81145, SAO 141250[7] | |
| Database references | |
| SIMBAD | data |
This is the brightest known B-type subdwarf star with a stellar classification of B5 VI. It is generating energy through the thermonuclear fusion of helium at its core (triple-alpha process).[3] The effective temperature of the star's outer envelope is about 35,500 K, giving it the characteristic blue-white hue of a B-type star. Although only about one seventh the diameter of the Sun, it radiates about 25 times as much due to its high temperature. HD 149382 has a visual companion located at an angular separation of 1 arcsecond.[9]
In 2009, a substellar companion, perhaps even a superjovian planet, was announced orbiting the star. This candidate object was estimated to have 8 to 23 times the mass of Jupiter.[5] In 2011, this discovery was thrown into doubt when an independent team of astronomers were unable to confirm the detection. Their observations rule out a companion with a mass greater than Jupiter orbiting with a period of less than 28 days.[9]