Zeta Trianguli Australis

Zeta Trianguli Australis
Observation data
Epoch J2000      Equinox J2000
Constellation Triangulum Australe
Right ascension 16h 28m 28.14362s[1]
Declination −70° 05′ 03.8419″[1]
Apparent magnitude (V) 4.91[2]
Characteristics
Spectral type F9V + M4V[2][3]
U−B color index +0.02[4]
B−V color index +0.55[5]
Astrometry
Radial velocity (Rv)+8.3[6] km/s
Proper motion (μ) RA: 200.742 mas/yr[7]
Dec.: 109.341 mas/yr[7]
Parallax (π)82.8699 ± 0.1627 mas[7]
Distance39.36 ± 0.08 ly
(12.07 ± 0.02 pc)
Absolute magnitude (MV)4.49[8]
Orbit[9]
Period (P)12.97662±0.00017 d
Eccentricity (e)0.01442±0.00021
Periastron epoch (T)JD 2452752.31955
Argument of periastron (ω)
(secondary)		252.98°±0.80°
Semi-amplitude (K1)
(primary)		7.4988±0.0016 km/s
Details
ζ TrA A
Mass1.12[10] M☉
Metallicity [Fe/H]−0.18[5] dex
Rotation13 days[5]
Rotational velocity (v sin i)3.23[11] km/s
Age600–900[12] Myr
ζ TrA B
Mass0.40[10] M☉
Other designations
CD−69°2558, FK5 610, GJ 624, HD 147584, HIP 80686, HR 6098, SAO 253554, LTT 6558[13]
Database references
SIMBADdata
ARICNSdata

Zeta Trianguli Australis (ζ TrA) is a spectroscopic binary star system in the southern constellation Triangulum Australe. The pair have a combined apparent visual magnitude of 4.90,[4] which is bright enough to be visible to the naked eye. Based on parallax measurements, the system is located at a distance of approximately 39.4 light years from the Sun.[7] After closing to within 31.3 ly (9.59 pc) some 436,600 years ago,[14] it is now drifting further away with a radial velocity of +8.3 km/s.[6]

The pair orbit each other once every 13 days, and the orbital eccentricity is a low 0.014, making their orbit nearly circular.[9] The primary component has a stellar classification of F9V, matching an F-type main-sequence star. It has a mass equal to 1.12 times the mass of the Sun.[10] The companion is a small red dwarf star with a class in the range of M1–7V[2] and 40% of the Sun's mass.[10] The age of the system is estimated at 600–900 million years.[12]

Somewhat surprisingly for a star located at a declination of 70° S, it is a candidate swarm member of the Ursa Major moving group.[15] However, there is some evidence to the contrary.[5]

  1. ^ a b Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference Ammler-von_Eiff_et_al_2016 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference aj132_1_161 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference MERMILLIOD was invoked but never defined (see the help page).
  5. ^ a b c d Cite error: The named reference aaa521_A12 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference GaiaEDR3 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Holmberg2009 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference mnras352_975 was invoked but never defined (see the help page).
  10. ^ a b c d Cite error: The named reference aj147_4_87 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference aaa520_A79 was invoked but never defined (see the help page).
  12. ^ a b Cite error: The named reference apj687 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Bailer-Jones_et_al_2018 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference crosswell was invoked but never defined (see the help page).