TY Coronae Borealis
Variable white dwarf in the constellation Corona Borealis
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TY Coronae Borealis, also known as Ross 808, is a white dwarf in the constellation Corona Borealis. It is 107 light-years distant from Earth,[2] and has a dim apparent magnitude of 14.4.[3]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Corona Borealis |
| Right ascension | 16h 01m 23.187s[2] |
| Declination | +36° 48′ 34.29″[2] |
| Apparent magnitude (V) | 14.435±0.018[3] |
| Characteristics | |
| Evolutionary stage | White dwarf |
| Spectral type | DA4.4[4] |
| Variable type | ZZ Ceti[5] |
| Astrometry | |
| Proper motion (μ) | RA: 101.113 mas/yr[2] Dec.: −545.353 mas/yr[2] |
| Parallax (π) | 30.4668±0.0187 mas[2] |
| Distance | 107.05 ± 0.07 ly (32.82 ± 0.02 pc) |
| Absolute magnitude (MV) | +11.81[6] |
| Details | |
| Mass | 0.593±0.028 to 0.615+0.024 −0.025[3] M☉ |
| Radius | 0.0131±0.0014[7] R☉ |
| Luminosity | (1.83±0.03)×10−3[8] L☉ |
| Surface gravity (log g) | 8.194[9] cgs |
| Temperature | 11,000[9] K |
| Age | 447 (white dwarf stage)[6] Myr |
| Other designations | |
| TY CrB, Ross 808, WD 1600+369, LTT 14769, NLTT 41782, 2MASS J16012317+3648351[4] | |
| Database references | |
| SIMBAD | data |
It is a pulsating white dwarf of the DAV (ZZ Ceti) type. The variation in the blue band is of 0.14 magnitudes, over a period of 15 minutes.[5] It was confirmed as a variable star in 1976, and now has the variable-star designation TY Coronae Borealis.[10] Being of this variable class, it has been a target for asteroseismic analyses, in attempt to derive its physical properties such as mass, radius and gravity.[9][11][8] However, it seems estimations of the stellar mass derived for this star using asteroseismology had been overestimated.[3]
TY Coronae Borealis has around 0.6 times the mass of the Sun[3] and a tiny diameter of only 1.3% that of the Sun.[7] It is a dim star, with 0.2% of the Sun's luminosity.[8] It has an effective temperature of about 11,000 K,[9] have taken 450 million years to cool to its temperature. This is also its age as a white dwarf.[6]