18 Boötis
Star in the constellation Boötes
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18 Boötis is a single[9] star in the northern constellation of Boötes,[8] located about 85 light years away from the Sun.[2] It is visible to the naked eye as a faint, yellow-white hued star with an apparent visual magnitude of 5.41.[1] This object is a suspected member of the Ursa Major Moving Group, based on velocity criteria.[10] It has a magnitude 10.84 optical companion at an angular separation of 163.7″ along a position angle of 219°, as of 2010.[11]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes[1] |
| Right ascension | 14h 19m 16.27966s[2] |
| Declination | +13° 00′ 15.4859″[2] |
| Apparent magnitude (V) | 5.41[1] |
| Characteristics | |
| Spectral type | F3 V[3] |
| B−V color index | 0.385±0.011[1] |
| Astrometry | |
| Radial velocity (Rv) | −0.40±0.7[1] km/s |
| Proper motion (μ) | RA: +105.273[2] mas/yr Dec.: −31.389[2] mas/yr |
| Parallax (π) | 38.1262±0.1323 mas[2] |
| Distance | 85.5 ± 0.3 ly (26.23 ± 0.09 pc) |
| Absolute magnitude (MV) | 3.33[1] |
| Details | |
| Mass | 1.31[4] M☉ |
| Radius | 1.4[5] R☉ |
| Luminosity | 3.90[1] L☉ |
| Surface gravity (log g) | 4.30[4] cgs |
| Temperature | 6,731±229[4] K |
| Metallicity [Fe/H] | −0.03±0.04[6] dex |
| Rotational velocity (v sin i) | 40.5±2.0[7] km/s |
| Age | 1.154[4] Gyr |
| Other designations | |
| 18 Boo, BD+13°2782, FK5 1372, GJ 3841, HD 125451, HIP 69989, HR 5365, SAO 100975, WDS J14193+1300[8] | |
| Database references | |
| SIMBAD | data |
This is an F-type main-sequence star with a stellar classification of F3 V.[3] Older surveys gave a class of F5 IV,[12] showing the luminosity class of a subgiant star. It shows strong evidence for short-term chromospheric variability, although it is not optically variable.[13]
18 Boötis is an estimated 1.15[4] billion years old and is spinning with a projected rotational velocity of 40.5 km/s.[7] It has 1.3[4] times the mass of the Sun and 1.4[5] times the Sun's radius. The star is radiating 3.9[1] times the luminosity of the Sun from its photosphere at an effective temperature of 6,731 K.[4] An infrared excess has been detected that suggests a cold debris disk is orbiting 34.9 AU from the host star with a blackbody temperature fit of 65 K.[5]