Nu2 Coronae Borealis
Red giant star in the constellation Corona Borealis
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Nu2 Coronae Borealis is a solitary,[11] orange-hued star located in the northern constellation of Corona Borealis. It is faintly visible to the naked eye, having an apparent visual magnitude of +5.4.[2] Based upon an annual parallax shift of 5.72 mas, it is located roughly 571 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction of 0.1 due to interstellar dust.[12]
ν2 Coronae Borealis (lower red star) in optical light | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Corona Borealis |
| Right ascension | 16h 22m 29.21832s[1] |
| Declination | +33° 42′ 12.5247″[1] |
| Apparent magnitude (V) | +5.396[2] |
| Characteristics | |
| Evolutionary stage | RGB[3][1] |
| Spectral type | K5 III[4] |
| U−B color index | +1.787[2] |
| B−V color index | +1.525[2] |
| Astrometry | |
| Radial velocity (Rv) | −41.1±0.2[5] km/s |
| Proper motion (μ) | RA: −5.537[1] mas/yr Dec.: +49.931[1] mas/yr |
| Parallax (π) | 5.7163±0.0624 mas[1] |
| Distance | 571 ± 6 ly (175 ± 2 pc) |
| Absolute magnitude (MV) | −0.78[6] |
| Details | |
| Mass | 1.1[7] M☉ |
| Radius | 64[1] R☉ |
| Luminosity | 880[1] L☉ |
| Surface gravity (log g) | 1.76[8] cgs |
| Temperature | 3,940[8] K |
| Metallicity [Fe/H] | −0.16[8] dex |
| Rotational velocity (v sin i) | 3.1[9] km/s |
| Other designations | |
| ν2 Coronae Borealis, 21 CrB, BD+34 2774, HD 147767, HIP 80214, HR 6108, SAO 65259[10] | |
| Database references | |
| SIMBAD | data |
This is an evolved red giant star with a stellar classification of K5 III.[4] Nu2 Coronae Borealis is 64 times bigger than the Sun, radiating 880 times the Sun's luminosity from its photosphere at an effective temperature of 3,940 K.
The star ν1 Coronae Borealis lies 6′ borth of ν2. ν1 is also a red giant with almost the same apparent magnitude, but is a more luminous asymptotic giant branch star.[13]