HD 130948
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 14h 50m 15.8110s |
| Declination | +23° 54′ 42.634″ |
| Apparent magnitude (V) | 5.99 |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | F9 IV-V |
| U−B color index | +0.01 |
| B−V color index | +0.576 |
| Variable type | BY Dra |
| Astrometry | |
| Radial velocity (Rv) | −1.5 km/s |
| Proper motion (μ) | RA: +144.396 mas/yr Dec.: +31.661 mas/yr |
| Parallax (π) | 54.9502±0.0343 mas |
| Distance | 59.35 ± 0.04 ly (18.20 ± 0.01 pc) |
| Absolute magnitude (MV) | +4.56 |
| Details | |
| Mass | 0.97 M☉ |
| Radius | 1.1 R☉ |
| Luminosity | 1.2 L☉ |
| Surface gravity (log g) | 4.18 cgs |
| Temperature | 5,780 K |
| Metallicity [Fe/H] | −0.20 dex |
| Rotation | 8.1 |
| Rotational velocity (v sin i) | 6.8 km/s |
| Age | 4.7 or 0.5 Gyr |
| Other designations | |
| HP Boötis, GJ 564, BD+24°2786, HD 130948, FK5 3172, HIP 72567, HR 5534, SAO 83553 | |
| Database references | |
| SIMBAD | data |
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.
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. Evolutionary models suggest that it is just reaching the end of its main sequence life.
Eric J. Gaidos et al. observed the star in 1998 and 1999, and discovered that it is a variable star. It was given its variable star designation, HP Boötis, in 2006.
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. The pair have a 10-year orbital period about the primary star, and their combined mass is 10.9% of the Sun's mass.
The space velocity components of this star through the Milky Way galaxy are (U, V, W) = (−14.0, 14.7, −0.1).