| |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Aries |
| Right ascension | 03h22m 45.24006s[1] |
| Declination | +20° 44′ 31.4382″[1] |
| Apparent magnitude (V) | +5.09[2] |
| Characteristics | |
| Spectral type | K3 III[3] |
| U−B color index | +1.27[2] |
| B−V color index | 1.238[4] |
| Astrometry | |
| Radial velocity (Rv) | +2.45 ± 0.24[4] km/s |
| Proper motion (μ) | RA: –51.59[1] mas/yr Dec.: –16.06[1] mas/yr |
| Parallax (π) | 10.27 ± 0.60 mas[1] |
| Distance | 320 ± 20 ly (97 ± 6 pc) |
| Absolute magnitude (MV) | +0.17[5] |
| Details | |
| Radius | 19[4] R☉ |
| Luminosity | 120[4] L☉ |
| Surface gravity (log g) | 2.1[4] cgs |
| Temperature | 4,406[4] K |
| Metallicity [Fe/H] | +0.02[4] dex |
| Rotational velocity (v sin i) | 3.4[4] km/s |
| Other designations | |
τ2 Ari, 63 Arietis, BD+20 551, HD 20893, HIP 15737, HR 1015, SAO 75899.[6] | |
| Database references | |
| SIMBAD | data |
Tau2 Arietis, Latinized from τ2 Arietis, is the Bayer designation for a binary star[7] in the northern constellationonAries. The combined apparent visual magnitude of this system is +5.09,[2] which is bright enough to be seen with the naked eye. With an annual parallax shift of 10.27 mas,[1] it is located at a distance of approximately 320 light-years (98parsecs) from Earth, give or take a 20 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.[8]
The primary component is an evolved giant star with a stellar classification of K3 III.[9] It has expanded to 19 times the radius of the Sun, from which it is radiating 120 times the Sun's luminosity.[4] This energy is being emitted into outer space from the outer atmosphere at an effective temperature of 4,406 K,[4] 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.[7]
{{cite web}}: CS1 maint: postscript (link)
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