Lambda Boötis
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 14h 16m 23.018s |
| Declination | +46° 05′ 17.90″ |
| Apparent magnitude (V) | +4.18 |
| Characteristics | |
| Spectral type | A0p λB |
| U−B color index | +0.05 |
| B−V color index | +0.08 |
| Variable type | δ Sct |
| Astrometry | |
| Radial velocity (Rv) | −7.9±1.6 km/s |
| Proper motion (μ) | RA: −187.698 mas/yr Dec.: 159.309 mas/yr |
| Parallax (π) | 32.5885±0.1410 mas |
| Distance | 100.1 ± 0.4 ly (30.7 ± 0.1 pc) |
| Absolute magnitude (MV) | +1.71±0.23 |
| Details | |
| Mass | 1.66+0.19 −0.16 M☉ |
| Radius | 1.7 R☉ |
| Luminosity | 19.1+9.0 −6.1 L☉ |
| Surface gravity (log g) | 4.188 cgs |
| Temperature | 8720 K |
| Rotational velocity (v sin i) | 100 km/s |
| Age | 2.8+1.1 −0.8 Gyr |
| Other designations | |
| Xuange, λ Boo, 19 Boötis, BD+46°1949, FK5 527, GC 19273, GJ 3837, HD 125162, HIP 69732, HR 5351, SAO 44965 | |
| Database references | |
| SIMBAD | data |
Lambda Boötis is a star in the northern constellation of Boötes. Its name is a Bayer designation that is Latinized from λ Boötis, and abbreviated Lam Boo or λ Boo. It has the official name Xuange, pronounced /ˈʃwɛnɡə/. With an apparent visual magnitude of +4.18, it is faintly visible to the naked eye. Based on parallax measurements, it is 100.1 light-years (30.7 pc) distant from Earth. This star is drifting closer to the Sun with a radial velocity of −8 km/s.
This is a white hued A-type main-sequence star with a stellar classification of A0p λB. It is the prototype of a group of rare stars known as Lambda Boötis stars, all of which are dwarf stars with unusually low abundances of metals in their spectra. Its diameter has been directly measured to be 1.7 times that of the Sun. This is a Delta Scuti variable star with a period of 33.1 minutes and an amplitude of 0.0020 in visual magnitude.
This star displays an infrared excess that may be the result of a circumstellar disk of orbiting debris, or else a bow wave from its motion through the interstellar medium.