Nu1 Coronae Borealis
Star in the constellation Corona Borealis
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Nu1 Coronae Borealis is a solitary,[8] red-hued star located in the northern constellation of Corona Borealis. It is faintly visible to the naked eye, having an apparent visual magnitude of 5.20.[2] Based upon an annual parallax shift of 5.02 mas,[1] it is located roughly 650 light years from the Sun. At its distance, the visual magnitude is diminished by an extinction of 0.1 due to interstellar dust.[9] This object is drifting closer with a radial velocity of −13 km/s.[1]
ν1 Coronae Borealis (upper red star) in optical light | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Corona Borealis |
| Right ascension | 16h 22m 21.42283s[1] |
| Declination | +33° 47′ 56.5880″[1] |
| Apparent magnitude (V) | 5.20[2] |
| Characteristics | |
| Evolutionary stage | AGB[3] |
| Spectral type | M2 III[4] |
| B−V color index | 1.64[4] |
| Astrometry | |
| Radial velocity (Rv) | −13.01±0.12[1] km/s |
| Proper motion (μ) | RA: +4.756 mas/yr[1] Dec.: −38.223 mas/yr[1] |
| Parallax (π) | 5.0245±0.0843 mas[1] |
| Distance | 650 ± 10 ly (199 ± 3 pc) |
| Absolute magnitude (MV) | −1.19[4] |
| Details | |
| Mass | 1.2[5] M☉ |
| Radius | 80.78±2.88[6] R☉ |
| Luminosity | 1,257±70[6] L☉ |
| Surface gravity (log g) | 1.86[5] cgs |
| Temperature | 3,828[6] K |
| Metallicity [Fe/H] | −0.21[5] dex |
| Other designations | |
| ν1 Coronae Borealis, 20 CrB, BD+34 2773, HD 147749, HIP 80197, HR 6107, SAO 65257[7] | |
| Database references | |
| SIMBAD | data |
This is an evolved red giant star with a stellar classification of M2 III.[4] It is a variable star of uncertain type, showing a change in brightness with an amplitude of 0.0114 magnitude and a frequency of 0.22675 cycles per day, or 4.41 days/cycle.[10] It has about 81 times the Sun's radius and is radiating nearly 1,300 times the Sun's luminosity from its photosphere at an effective temperature of 3,828 K.[6]
The star ν2 Coronae Borealis lies 6′ south of ν1. ν2 is also a red giant with almost the same apparent magnitude, but is a less luminous red giant branch star.[11]