| |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Boötes |
| Right ascension | 15h31m 46.98170s[1] |
| Declination | +40° 53′ 57.5405″[1] |
| Apparent magnitude (V) | 5.02[2] (5.80 + 5.80)[3] |
| Characteristics | |
| Spectral type | A5 V[4] |
| U−B color index | +0.11[2] |
| B−V color index | +0.07[2] |
| R−I color index | 0.04 |
| Astrometry | |
| Radial velocity (Rv) | −16.6±3.7[5] km/s |
| Proper motion (μ) | RA: -21.905[1] mas/yr Dec.: -7.876[1] mas/yr |
| Parallax (π) | 7.8618 ± 0.1449 mas[1] |
| Distance | 415 ± 8 ly (127 ± 2 pc) |
| Absolute magnitude (MV) | −0.59[6] |
| Orbit[7] | |
| 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[8] M☉ |
| Radius | 6.21+1.07 −0.81[1] R☉ |
| Luminosity | 135±3[1] L☉ |
| Temperature | 7894+574 −600[1] K |
| Rotational velocity (v sin i) | 217[8] km/s |
| Other designations | |
ν2 Boo, ψ2 Her, 53 Boötis, BD+41° 2611, GC 20883, HD 138629, HIP 76041, HR 5774, SAO 45590, ADS 9688, CCDM 15318+4054, WDS J15318+4054AB[9] | |
| Database references | |
| SIMBAD | data |
| Data sources: | |
| Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) | |
Nu2 Boötis is a white-hued binary star[10] system in the northern constellationofBoötes. It is faintly visible to the naked eye with a combined apparent visual magnitude of 5.02.[2] Based upon an annual parallax shift of 7.86 mas as seen from the Earth,[1] it is located roughly 415 light years from the Sun. The system is moving closer to the Sun with a radial velocity of −16.6 km/s.[5]
This stellar pair have a nearly circular orbit with a period of nine years and a semimajor axis of 0.0615 arc seconds.[10] 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.[4] This has been identified as an A-type shell star, suggesting there is a circumstellar disk of gas orbiting one or both stars.[11] There are two other stars that appear close to the pair, termed C and D, but they are physically unrelated.[12]
Ptolemy considered Nu2 Boötis to be shared by Hercules, and Bayer assigned it a designation in both constellations: Nu2 Boötis (ν2 Boo) and Psi2 Herculis (ψ2 Her). When the modern constellation boundaries were fixed in 1930, the latter designation dropped from use.[13]
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