Nu2 Boötis is a white-hued binary star[10] system in the northern constellation of Boötes. 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]
Quick Facts Constellation, Right ascension ...
Nu2 Boötis
ν 1 (right) and ν 2 (left) Boötis in optical light |
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) |
Constellation |
Boötes |
Right ascension |
15h 31m 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 |
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|
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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] |
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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 |
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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 |
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Other designations |
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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 |
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SIMBAD | data |
Data sources: |
Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) |
Close
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]
Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
Hauck, B.; Jaschek, C. (February 2000), "A-shell stars in the Geneva system", Astronomy and Astrophysics, 354: 157–162, Bibcode:2000A&A...354..157H.
- Hoffleit; et al. (1991), "HR 5774", Bright Star Catalogue (5th Revised ed.), retrieved 2017-09-13.
- "Nu2 Boötis", Aladin previewer, Centre de Données astronomiques de Strasbourg, retrieved 2017-09-12.