Tau2 Arietis
Star in the constellation Aries
From Wikipedia, the free encyclopedia
Tau2 Arietis is a binary star[9] system in the northern constellation on Aries. Its name is a Bayer designation that is Latinized from τ2 Arietis, and abbreviated Tau2 Ari or τ2 Ari. The combined apparent visual magnitude of this system is +5.09,[3] which is bright enough to be seen with the naked eye. With an annual parallax shift of 9.76 mas,[10] it is located at a distance of approximately 334 light-years (102 parsecs) from Earth, give or take an 8 light-year margin of error. At this distance the brightness of the star is diminished by 0.18 in magnitude because of extinction from interstellar gas and dust.[11] The system is receding from the Sun with a radial velocity of +2.5 km/s.[6]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Aries[1] |
| Right ascension | 03h 22m 45.241s[2] |
| Declination | +20° 44′ 31.44″[2] |
| Apparent magnitude (V) | +5.09[3] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | K3 III[4][5] |
| U−B color index | +1.27[3] |
| B−V color index | 1.238[6] |
| Astrometry | |
| Radial velocity (Rv) | +2.45±0.24[6] km/s |
| Proper motion (μ) | RA: −53.633 mas/yr[2] Dec.: −14.447 mas/yr[2] |
| Parallax (π) | 9.7639±0.2442 mas[2] |
| Distance | 334 ± 8 ly (102 ± 3 pc) |
| Absolute magnitude (MV) | +0.17[1] |
| Details | |
| Mass | 2.04±0.60[7] M☉ |
| Radius | 19[6] R☉ |
| Luminosity | 120[6] L☉ |
| Surface gravity (log g) | 2.23±0.11[7] cgs |
| Temperature | 4,479±92[7] K |
| Metallicity [Fe/H] | +0.02[6] dex |
| Rotational velocity (v sin i) | 3.4[6] km/s |
| Age | 1.6+0.6 −0.4[7] Gyr |
| Other designations | |
| τ2 Ari, 63 Arietis, BD+20 551, GC 4026, HD 20893, HIP 15737, HR 1015, SAO 75899, PPM 92448, WDS J03228+2045A[8] | |
| Database references | |
| SIMBAD | data |
The primary component is an evolved giant star with a stellar classification of K3 III.[4] It is an estimated 1.6 billion years old and is spinning with a projected rotational velocity of 3.4 km/s.[6] With double the mass of the Sun,[7] it has expanded to 19 times the radius of the Sun.[6] The star is radiating 120 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,406 K,[6] giving it the cool orange glow of a K-type star. At an angular separation of 0.53 arcseconds is a magnitude 8.50 companion.[9]