46 Boötis
Star in the constellation Boötes
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46 Boötis is a binary star system in the northern constellation of Boötes, located mid-way between α Coronae Borealis and ε Boötis.[5] It has the Bayer designation b Boötis; 46 Boötis is the Flamsteed designation.[8] The system lies 478 light-years away from the Sun based on parallax,[1] and is visible to the naked eye as a faint, orange-hued star with a combined apparent visual magnitude of 5.67.[2] It is moving away from the Earth with a heliocentric radial velocity of +19 km/s.[2] The light from this system displays an unusually high level of polarization due to interstellar dust.[5]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 15h 08m 23.78241s[1] |
| Declination | +26° 18′ 04.1464″[1] |
| Apparent magnitude (V) | 5.67[2] |
| Characteristics | |
| Spectral type | K2 III[3] |
| U−B color index | +1.24[4] |
| B−V color index | +1.240±0.015[2] |
| Astrometry | |
| Radial velocity (Rv) | +19.31±0.30[2] km/s |
| Proper motion (μ) | RA: +4.454[1] mas/yr Dec.: −15.185[1] mas/yr |
| Parallax (π) | 6.8288±0.0883 mas[1] |
| Distance | 478 ± 6 ly (146 ± 2 pc) |
| Absolute magnitude (MV) | −0.31[2] |
| Orbit[5] | |
| Period (P) | 2,567.1±0.6 d |
| Semi-major axis (a) | 11.2 mas[6] |
| Eccentricity (e) | 0.8315±0.0027 |
| Inclination (i) | 62[6]° |
| Longitude of the node (Ω) | 82.6±6.6° |
| Periastron epoch (T) | 2,448,356.6 JD |
| Argument of periastron (ω) (secondary) | 175.3±0.7[5]° |
| Semi-amplitude (K1) (primary) | 9.25±0.10[5] km/s |
| Details | |
| 46 Boo A | |
| Radius | 23.35+0.85 −0.67[1] R☉ |
| Luminosity | 175.8±2.8[1] L☉ |
| Temperature | 4,349+64 −76[1] K |
| Metallicity [Fe/H] | −0.27±0.15[7] dex |
| Other designations | |
| b Boo, 46 Boo, BD+26°2656, FK5 1396, GC 20367, HD 134320, HIP 74087, HR 5638, SAO 83682[8] | |
| Database references | |
| SIMBAD | data |
This is a single-lined spectroscopic binary with an orbital period of 7.03 years and a large eccentricity of 0.83.[5] The primary member, designated component A, is an aging giant star with a stellar classification of K2 III.[3] As a consequence of exhausting the hydrogen at its core, it has expanded to 23[1] times the Sun's radius. It is radiating 176[1] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,349 K.[1] The companion star, component B, is most likely a lower main-sequence star with 0.6–0.8 times the Sun's mass.[6]