Nu2 Boötis
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Boötes |
| Right ascension | 15h 31m 46.983s |
| Declination | +40° 53′ 57.61″ |
| Apparent magnitude (V) | 5.02 (5.80 + 5.80) |
| Characteristics | |
| Spectral type | A5 V |
| U−B color index | +0.11 |
| B−V color index | +0.07 |
| R−I color index | 0.04 |
| Astrometry | |
| Radial velocity (Rv) | −16.6±3.7 km/s |
| Proper motion (μ) | RA: −22.887 mas/yr Dec.: −12.041 mas/yr |
| Parallax (π) | 7.3894±0.1816 mas |
| Distance | 440 ± 10 ly (135 ± 3 pc) |
| Absolute magnitude (MV) | −0.59 |
| Orbit | |
| Period (P) | 9.026±0.017 yr |
| Semi-major axis (a) | 0.0615±0.0007″ |
| Eccentricity (e) | 0.006±0.015 |
| Inclination (i) | 109.7±1.2° |
| Longitude of the node (Ω) | 199.4±0.9° |
| Periastron epoch (T) | 2000.75±0.24 |
| Argument of periastron (ω) (secondary) | 293±9° |
| Details | |
| Mass | 2.84±0.11 M☉ |
| Radius | 6.21+1.07 −0.81 R☉ |
| Luminosity | 135±3 L☉ |
| Temperature | 7894+574 −600 K |
| Rotational velocity (v sin i) | 217 km/s |
| Other designations | |
| ν2 Boo, ψ Her, 53 Boötis, BD+41°2611, GC 20883, HD 138629, HIP 76041, HR 5774, SAO 45590, ADS 9688, CCDM 15318+4054, WDS J15318+4054AB | |
| Database references | |
| SIMBAD | data |
| Data sources: | |
| Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) | |
Nu2 Boötis is a white-hued binary star system in the northern constellation of Boötes. Its name is a Bayer designation that is Latinized from ν2 Boötis, and abbreviated Nu2 Boo or ν2 Boo. This system is faintly visible to the naked eye as a point of light with a combined apparent visual magnitude of 5.02. Based upon an annual parallax shift of 7.86 mas as seen from the Earth, it is located approximately 441 light-years (135 pc) light years from the Sun. The system is moving closer to the Sun with a radial velocity of −16.6 km/s.
This stellar pair have a nearly circular orbit with a period of nine years and a semimajor axis of 0.0615 arc seconds. They are both of visual magnitude 5.80 and display a similar spectrum, with the primary, component A, being an A-type main sequence star with a stellar classification of A5 V. This has been identified as an A-type shell star, suggesting there is a circumstellar disk of gas orbiting one or both stars. There are two other stars that appear close to the pair, termed C and D, but they are physically unrelated.
Ptolemy considered Nu Boötis to be shared by Hercules, and Bayer assigned it a designation in both constellations: Nu Boötis (ν Boo) and Psi Herculis (ψ Her). When the modern constellation boundaries were fixed in 1930, the latter designation dropped from use.