HD 130948
Star in the constellation Boötes
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HD 130948 or HP Boötis is a variable star with 2 brown dwarfs in the constellation Boötes. With an apparent magnitude of 6.0, it is faintly visible to the naked eye under very good observing conditions. It has a stellar classification of G1V, which means it is a main sequence star with a mass and surface temperature that are similar to the Sun.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes[2] |
| Right ascension | 14h 50m 15.8110s[3] |
| Declination | +23° 54′ 42.634″[3] |
| Apparent magnitude (V) | 5.99[4] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | F9 IV-V[5] |
| U−B color index | +0.01[6] |
| B−V color index | +0.576[4] |
| Variable type | BY Dra[7] |
| Astrometry | |
| Radial velocity (Rv) | −1.5[8] km/s |
| Proper motion (μ) | RA: +144.396[3] mas/yr Dec.: +31.661[3] mas/yr |
| Parallax (π) | 54.9502±0.0343 mas[3] |
| Distance | 59.35 ± 0.04 ly (18.20 ± 0.01 pc) |
| Absolute magnitude (MV) | +4.56[2] |
| Details | |
| Mass | 0.97[9] M☉ |
| Radius | 1.1[3] R☉ |
| Luminosity | 1.2[3] L☉ |
| Surface gravity (log g) | 4.18[9] cgs |
| Temperature | 5,780[9] K |
| Metallicity [Fe/H] | −0.20[9] dex |
| Rotation | 8.1[10] |
| Rotational velocity (v sin i) | 6.8[10] km/s |
| Age | 4.7[11] or 0.5[12] Gyr |
| Other designations | |
| HP Boötis, GJ 564, BD+24°2786, HD 130948, FK5 3172, HIP 72567, HR 5534, SAO 83553[6] | |
| Database references | |
| SIMBAD | data |
The estimated age of HD 130948 is similar to the Sun at 4.7 billion years (Gyr) old, but it has a lower proportion of elements (63%) other than hydrogen or helium. However, a separate study in 2009 gave a much younger age of 0.5±0.3 Gyr and a higher metallicity that is very similar to the Sun.[12] Evolutionary models suggest that it is just reaching the end of its main sequence life.[3]
Eric J. Gaidos et al. observed the star in 1998 and 1999, and discovered that it is a variable star.[13] It was given its variable star designation, HP Boötis, in 2006.[7]
In 2002, a pair of co-orbiting brown dwarfs were discovered in orbit around this star. They were found using an adaptive optics instrument on the Gemini North 8m telescope in Hawaii.[14] The pair have a 10-year orbital period about the primary star, and their combined mass is 10.9% of the Sun's mass.[12]
The space velocity components of this star through the Milky Way galaxy are (U, V, W) = (−14.0, 14.7, −0.1).[9]