Tau2 Aquarii

For other stars with this Bayer designation, see τ Aquarii.
τ2 Aquarii
Location of τ2 Aquarii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 22h 49m 35.50157s[1]
Declination –13° 35′ 33.4767″[1]
Apparent magnitude (V) +4.042[2] (3.98 to 4.04)[3]
Characteristics
Spectral type K5 III[4] or M0 III[5]
U−B color index +1.948[2]
B−V color index +1.566[2]
Variable type Suspected[3]
Astrometry
Radial velocity (Rv)+1.0[6] km/s
Proper motion (μ) RA: –13.71[1] mas/yr
Dec.: –39.03[1] mas/yr
Parallax (π)10.27 ± 0.29 mas[1]
Distance318 ± 9 ly
(97 ± 3 pc)
Absolute magnitude (MV)−1.28[7]
Details
Radius51.5+4.6
−5.5[8] R☉
Luminosity614±27[8] L☉
Surface gravity (log g)1.63[9] cgs
Temperature4,007+232
−166[8] K
Other designations
τ2 Aquarii, 71 Aquarii, NSV 14329, BD–14° 6354, FK5 861, HD 216032, HIP 112716, HR 8679, SAO 165321, WDS J22496-1336A[10]
Database references
SIMBADdata

Tau2 Aquarii, Latinized from τ2 Aquarii, is the Bayer designation for a single[11] star in the equatorial constellation of Aquarius. It is visible to the naked eye with an apparent visual magnitude of +4.0.[2] Because the star lies near the ecliptic it is subject to occultations by the Moon.[12] The star is located at a distance of approximately 318 light years from the Sun based on parallax.[1]

This is an orange-hued[13] red giant star with a stellar classification of K5 III.[4] After exhausting the supply of hydrogen at its core, the aging star cooled and expanded off the main sequence. It now has 52 times the radius of the Sun and is radiating 614 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,007 K.[8] This is a suspected variable star with a brightness that has been measured ranging from visual magnitude 3.98 down to 4.04.[3]

A magnitude 9.94 visual companion to this star was reported by W. Herschel in 1782, and it has the modern discovery code 'H 6 97'. As of 2010, it was located at a wide angular separation of 132.40″ from the brighter star along a position angle of 297°.[14]

  1. ^ a b c d e f Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference sps1966 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference houk1978 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Keenan_McNeil_1989 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference scfs was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference pace was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Bordé_et_al_2002 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Eggleton_Tokovinin_2008 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference White1987 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference csiro was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference WDSC2014 was invoked but never defined (see the help page).