BX Boötis
Star in the constellation Boötes
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BX Boötis is a star in the northern constellation of Boötes. It is a dim star near the lower limit of visibility to the naked eye, having a nominal apparent visual magnitude of 6.35.[10] Based upon an annual parallax shift of 6.3665 mas,[2] it is located 512 light years away. At that distance, the visual magnitude of the star is diminished by an extinction of 0.13 due to interstellar dust.[13] It is moving closer with a heliocentric radial velocity of −11 km/s.[8]
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Boötes |
| Right ascension | 15h 00m 38.7179s[2] |
| Declination | +47° 16′ 38.792″[2] |
| Apparent magnitude (V) | 6.33 to 6.41[3] |
| Characteristics | |
| Spectral type | A0 Vsp SiSrCr[4] or B9 Vp SiCrSr[5] |
| B−V color index | −0.099±0.004[6] |
| Variable type | α2 CVn[7] |
| Astrometry | |
| Radial velocity (Rv) | −10.7±1.8[8] km/s |
| Proper motion (μ) | RA: -8.999[2] mas/yr Dec.: 15.852[2] mas/yr |
| Parallax (π) | 6.3665±0.0287 mas[2] |
| Distance | 512 ± 2 ly (157.1 ± 0.7 pc) |
| Absolute magnitude (MV) | 0.21[6] |
| Details | |
| Mass | 2.70±0.09[9] M☉ |
| Radius | 2.51[10] R☉ |
| Luminosity | 72.4+10.8 −12.1[9] L☉ |
| Surface gravity (log g) | 4.50[11] cgs |
| Temperature | 9,164[11] K |
| Metallicity [Fe/H] | +0.63[11] dex |
| Rotation | 2.88756 d[1] |
| Rotational velocity (v sin i) | 30[12] km/s |
| Age | 235[13] Myr |
| Other designations | |
| BX Boo, BD+47° 2192, FK5 3247, HD 133029, HIP 73454, HR 5597, SAO 45326[14] | |
| Database references | |
| SIMBAD | data |
The variability of BX Boötis was probably discovered by Gerhard Robert Miczaika. It was announced in a 1954 IAU publication, where he discusses photo-electric measurements of spectrum variables. He wrote "The magnetic-field variable HD 133129 is likewise variable in magnitude with a small amplitude."[15] HD 133129 is not BX Boötis, but HD 133029 is. Unlike BX Boötis, HD 133129 does not match Miczaika's description of the star. Kukarkin et al. apparently concluded there was a typographical error in Miczaika's announcement, because they cited Miczaika's 1954 announcement when they gave BX Boötis its variable star designation in 1972.[16]
This is a magnetic CP star[1] with a stellar classification of A0 Vsp SiSrCr,[4] indicating this is an A-type main-sequence star. The spectrum has very weak lines of helium but displays strong overabundances of silicon and all of the heavier elements except nickel.[17] It is classified as an Alpha² Canum Venaticorum variable[7] with a magnitude that varies from 6.33 to 6.41[3] over a period of 2.88756 days.[1]
BX Boötis is 235[13] million years old with a projected rotational velocity of 30[12] km/s. It has 2.7[9] times the mass of the Sun and 2.5[10] times the Sun's radius. The star is radiating around 72[9] times the Sun's luminosity from its photosphere at an effective temperature of 9,164 K.[11]