| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 14h 46m 05.94566s[2] |
| Declination | +15° 07′ 54.4332″[2] |
| Apparent magnitude (V) | 5.78[3](5.33 to 5.71)[4] |
| Characteristics | |
| Spectral type | M5III[5] |
| U−Bcolor index | +1.26[6] |
| B−Vcolor index | 1.335±0.021[3] |
| Variable type | Lb?[4] |
| Astrometry | |
| Radial velocity (Rv) | −22.52±0.65[7] km/s |
| Proper motion (μ) | RA: −85.49[2]mas/yr Dec.: +18.86[2]mas/yr |
| Parallax (π) | 4.04±0.38 mas[2] |
| Distance | 810 ± 80 ly (250 ± 20 pc) |
| Absolute magnitude (MV) | −1.17[3] |
| Details | |
| Mass | 3.1±0.5[5] M☉ |
| Radius | 210±21[5] R☉ |
| Luminosity | 521.51[3] L☉ |
| Temperature | 3,400[5] K |
| Rotational velocity (v sin i) | 8.5 or 11[5] km/s |
| Other designations | |
| EK Boo,BD+15° 2758,FK5 3168,HD 130144,HIP 72208,HR 5512,SAO 101200[8] | |
| Database references | |
| SIMBAD | data |
HD 130144 is avariable star in the northernconstellation ofBoötes. It has thevariable star designationEK Boötis (or EK Boo), whileHD 130144 is the designation from theHenry Draper Catalogue. The star is faintly visible to thenaked eye with anapparent visual magnitude that ranges from 5.33 down to 5.71.[4]Parallax measurements provide a distance estimate of approximately 810 light years from theSun. It is drifting closer with aradial velocity of −23 km/s.[7]
The brightness of HD 130144 was discovered to be variable when theHipparcos satellite data was analyzed. It was given its variable star designation in 1999.[9] This is an agingred giant star with astellar classification of M5III.[5] It has an estimated 3.1 times themass of the Sun and has expanded to around 210 times theSun's radius.[5] EK Boo is classified as aslow irregular variable that ranges in luminosity with an amplitude of 0.38 in magnitude and no apparent periodicity. This is anX-ray source, and was possibly the first M-type giant star to have amagnetic field directly detected.[10] The strength of the field ranges from –0.1 to8 G.[11]
HD 130144 has a high rotation rate for a star of this class, which may be the result ofdredge-up ofangular momentum from the interior, or else a merger with an orbiting companion.[11] A long-term trend in the radial velocity data suggests this star has an orbiting companion. Most likely this is an activered dwarf that is responsible for most of the X-ray emission from the system.[10] There is nearbyvisual companion at an angular separation of0.20″ along aposition angle of 82.2° (as of 2010).[12]
