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]

References

  1. ^ a b van Leeuwen, Floor (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752v1, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600. Note: see VizieR catalogue I/311.
  2. ^ a b c Ammler-von Eiff, M.; et al. (June 2016), "Coronagraphic search for wide substellar companions among members of the Ursa Major moving group", Astronomy & Astrophysics, 591, id. A84, arXiv:1603.04616, Bibcode:2016A&A...591A..84A, doi:10.1051/0004-6361/201526625.
  3. ^ Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637, S2CID 119476992.
  4. ^ a b Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data. SIMBAD, Bibcode:1986EgUBV........0M.
  5. ^ a b c d Maldonado, J.; et al. (October 2010), "A spectroscopy study of nearby late-type stars, possible members of stellar kinematic groups", Astronomy and Astrophysics, 521: A12, arXiv:1007.1132, Bibcode:2010A&A...521A..12M, doi:10.1051/0004-6361/201014948, S2CID 119209183.
  6. ^ a b Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  7. ^ a b c Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  8. ^ Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191, S2CID 118577511.
  9. ^ a b Skuljan, Jovan (2004), "Accurate orbital parameters for the bright southern spectroscopic binary ζ Trianguli Australis – an interesting case of a near-circular orbit", Monthly Notices of the Royal Astronomical Society, 352 (3): 975, Bibcode:2004MNRAS.352..975S, doi:10.1111/j.1365-2966.2004.07988.x.
  10. ^ a b c d Tokovinin, Andrei (April 2014), "From Binaries to Multiples. II. Hierarchical Multiplicity of F and G Dwarfs", The Astronomical Journal, 147 (4): 14, arXiv:1401.6827, Bibcode:2014AJ....147...87T, doi:10.1088/0004-6256/147/4/87, S2CID 56066740, 87.
  11. ^ Martínez-Arnáiz, R.; et al. (September 2010), "Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter", Astronomy and Astrophysics, 520: A79, arXiv:1002.4391, Bibcode:2010A&A...520A..79M, doi:10.1051/0004-6361/200913725, S2CID 43455849.
  12. ^ a b Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008), "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics", The Astrophysical Journal, 687 (2): 1264–1293, arXiv:0807.1686, Bibcode:2008ApJ...687.1264M, doi:10.1086/591785, S2CID 27151456.
  13. ^ "zet TrA". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2024-10-21.
  14. ^ Bailer-Jones, C.A.L.; et al. (2018), "New stellar encounters discovered in the second Gaia data release", Astronomy & Astrophysics, 616: A37, arXiv:1805.07581, Bibcode:2018A&A...616A..37B, doi:10.1051/0004-6361/201833456, S2CID 56269929.
  15. ^ Croswell, Ken (2005), "Descendants of the Dipper", Astronomy, 33 (3): 40–45, Bibcode:2005Ast....33c..40C, ISSN 0091-6358.