R Boötis is a variable star in the northern constellation of Boötes. Typically the star is too faint to be readily visible to the naked eye, with a brightness that fluctuates between apparent visual magnitudes of 9.98.[5] The distance to this star is approximately 2,150 light years based on parallax measurements.[2] It is drifting closer with a radial velocity of about −58 km/s.[7]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 14h 37m 11.57616s[2] |
| Declination | 26° 44′ 11.6562″[2] |
| Apparent magnitude (V) | 6.0 - 13.3[3] |
| Characteristics | |
| Spectral type | M4-8e[4] |
| B−V color index | 1.50±0.51[5] |
| Variable type | Mira variable[3][6] |
| Astrometry | |
| Radial velocity (Rv) | −58.0±4.7[7] km/s |
| Proper motion (μ) | RA: –25.537[2] mas/yr Dec.: 11.968[2] mas/yr |
| Parallax (π) | 1.5204 ± 0.0586 mas[2] |
| Distance | 2,150 ± 80 ly (660 ± 30 pc) |
| Details | |
| Mass | 0.86[8] M☉ |
| Radius | 245[9] R☉ |
| Luminosity | 5,900[10] L☉ |
| Surface gravity (log g) | −0.44[8] cgs |
| Temperature | 2,640[8] K |
| Metallicity [Fe/H] | 0.55[8] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
The variability of this star was discovered by German astronomer F. W. Argelander in 1857.[12] It is classified as a Mira-type pulsating variable that ranges in brightness from magnitude 6.0 down to 13.3 with a period of 223.11 days.[3][6] The stellar classification of the star ranges from M4e to M8e,[4] where the 'e' indicates emission features in the spectrum.
The angular diameter of R Boötis has been measured at 3.45±0.1 mas,[13] which at its estimated distance of 660 parsecs[2] gives a physical size 245 times solar.[9]