34 Boötis
Star in the constellation of Boötes
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34 Boötis is a single[8] variable star[3] in the northern constellation Boötes, located around 700 light years away from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction of 0.49±0.02 due to interstellar dust.[6] It has the variable star designation W Boötis; 34 Boötis is the Flamsteed designation. This object is visible to the naked eye as a faint, red-hued star with a baseline apparent visual magnitude of 4.80.[2] It is moving away from the Earth with a heliocentric radial velocity of +5.6 km/s.[2]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 14h 43m 25.36304s[1] |
| Declination | +26° 31′ 40.2663″[1] |
| Apparent magnitude (V) | 4.80[2] (4.49 - 5.40[3]) |
| Characteristics | |
| Evolutionary stage | AGB[4] |
| Spectral type | M3− III[5] |
| B−V color index | 1.672±0.006[2] |
| Variable type | Semi-regular[3] |
| Astrometry | |
| Radial velocity (Rv) | +5.60±0.49[2] km/s |
| Proper motion (μ) | RA: −13.57[1] mas/yr Dec.: −16.08[1] mas/yr |
| Parallax (π) | 4.63±0.28 mas[1] |
| Distance | 700 ± 40 ly (220 ± 10 pc) |
| Absolute magnitude (MV) | −1.86[2] |
| Details[6] | |
| Mass | 2.20±0.23 M☉ |
| Radius | 129.36+8.42 −7.49 R☉ |
| Luminosity | 2,802±367 L☉ |
| Surface gravity (log g) | 1.24 cgs |
| Temperature | 3,691±50 K |
| Age | 1.05±0.27 Gyr |
| Other designations | |
| 34 Boo, W Boötis, BD+27°2413, FK5 1383, GC 19831, HD 129712, HIP 71995, HR 5490, SAO 83488[7] | |
| Database references | |
| SIMBAD | data |
This is an aging red giant star with a stellar classification of M3− III,[5] which indicates it has exhausted the supply of hydrogen at its core and evolved off the main sequence branch. It is classified as a semiregular variable with a brightness that varies from magnitude +4.49 down to +5.4 with a period of 25 days,[3] with some evidence of longer term variation and mode switching.[9] The star is around a billion years old with 2.2 times the mass of the Sun and has expanded to 129 times the size of the Sun. It is radiating 2,802 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 3,691 K.[6]
The parallax calculated in the new Hipparcos reduction is 4.63±0.28 mas,[1] and in Gaia Data Release 2 the parallax is given as 6.3168±0.2900 max.[10] Each has a margin of error of about 5%, but they differ from each other by far more than 5%.