Tau2 Arietis

For other stars with this Bayer designation, see τ Arietis.
τ2
Location of τ2 Arietis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Aries
Right ascension 03h 22m 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]
Distance320 ± 20 ly
(97 ± 6 pc)
Absolute magnitude (MV)+0.17[5]
Details
Radius19[4] R☉
Luminosity120[4] L☉
Surface gravity (log g)2.1[4] cgs
Temperature4,406[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
SIMBADdata

Tau2 Arietis, Latinized from τ2 Arietis, is the Bayer designation for a binary star[7] in the northern constellation on Aries. 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 (98 parsecs) 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]

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  2. ^ a b c Cite error: The named reference mnras133_475 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference mnras374_2_664 was invoked but never defined (see the help page).
  4. ^ a b c d e f g h i j Cite error: The named reference aj135_1_209 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference mnras389_2_869 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference aaa430_165 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference apj116 was invoked but never defined (see the help page).