Tau2 Capricorni

For other stars with this Bayer designation, see τ Capricorni.
Tau2 Capricorni
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Capricornus
Right ascension 20h 39m 16.31779s[1]
Declination −14° 57′ 17.1352″[1]
Apparent magnitude (V) 5.20 (5.77 + 9.5 + 6.19)[2]
Characteristics
Spectral type B6III + ? + B6IV[2]
Astrometry
Radial velocity (Rv)−4.1±2.1[3] km/s
Proper motion (μ) RA: +2.62[1] mas/yr
Dec.: −19.46[1] mas/yr
Parallax (π)2.87 ± 0.65 mas[1]
Distanceapprox. 1,100 ly
(approx. 350 pc)
Orbit[4]
Primaryτ2 Cap A
Companionτ2 Cap B
Period (P)420 yr
Semi-major axis (a)0.48″
Eccentricity (e)0.73
Inclination (i)75°
Longitude of the node (Ω)93.0°
Periastron epoch (T)1915.0
Argument of periastron (ω)
(secondary)		270°
Details
A
Mass5.01±0.35[5] M☉
Luminosity (bolometric)1,893[5] L☉
Surface gravity (log g)3.90[6] cgs
Temperature15,439[6] K
Metallicity [Fe/H]0.14[6] dex
Rotational velocity (v sin i)170[7] km/s
Other designations
τ2 Cap, 14 Capricorni, BD−15°5743, GC 28748, HD 196662, HIP 101923, HR 7889, SAO 163771, ADS 14099, CCDM J20392-1457, WDS J20393-1457[8]
Database references
SIMBADdata

Tau2 Capricorni, Latinized from τ2 Capricorni, is a triple star[2] system in the constellation Capricornus. It is approximately 1,100 light years from Earth based on parallax. The system has a blue-white hue and a combined apparent visual magnitude of +5.20.[2] Because it is positioned near the ecliptic, τ2 Capricorni can be occulted by the Moon.[9]

The primary, component A, is a B-type giant with a stellar classification of B6III and an apparent magnitude of +5.8.[2] It has five[5] times the mass of the Sun and is spinning rapidly with a projected rotational velocity of 170 km/s.[7] The star is radiating 1,893[5] times the luminosity of the Sun from its photosphere at an effective temperature of 15,439 K.[6]

At an angular separation of only 0.34 arcseconds is the companion, component B, a B-type subgiant star with a class of B6IV[2] and an apparent magnitude of +6.3. These two stars orbit around their common centre of mass once every 420 years.[4] A possible third component with an apparent magnitude of +9.5,[2] detected by studying the star during occultation, is located 0.052 arcseconds away from the A component.[10]

  1. ^ a b c d e Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d e f g Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Kharchenko2007 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Hartkopf2006 was invoked but never defined (see the help page).
  5. ^ a b c d Cite error: The named reference Hohle2010 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Koleva2012 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Abt2002 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Radick1980 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference bsc was invoked but never defined (see the help page).