Delta Trianguli

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Delta Trianguli
Diagram showing star positions and boundaries of the Triangulum constellation and its surroundings
Cercle rouge 100%.svg

Location of δ Trianguli (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Triangulum
Right ascension 02h 17m 03.23016s[1]
Declination +34° 13′ 27.2260″[1]
Apparent magnitude (V) +4.865[2]
Spectral type G0V / G9V to K4V[3]
U−B color index +0.02[4]
B−V color index +0.61[4]
Radial velocity (Rv) −5.70[5] km/s
Proper motion (μ) RA: 1151.83[1] mas/yr
Dec.: −246.89[1] mas/yr
Parallax (π) 92.73 ± 0.39[1] mas
Distance 35.2 ± 0.1 ly
(10.78 ± 0.05 pc)
Absolute magnitude (MV) 4.69[2]
Mass 1.0/0.8[6] M
Radius 0.98[7] R
Surface gravity (log g) 4.5[8] cgs
Temperature 6,215/4,493[3] K
Metallicity [Fe/H] −0.39[2] to −0.30[8] dex
Rotational velocity (v sin i) 10.00[5] km/s
Age 8.5[9] to 9.0[2] Gyr
Companion Delta Trianguli B
Period (P) 10.0200 days
Semi-major axis (a) 9.80 ± 0.06 mas
Eccentricity (e) 0.020 ± 0.005
Inclination (i) 167 ± 3°
Longitude of the node (Ω) 15 ± 9°
Other designations
δ Trianguli, δ Tri, Delta Tri, 8 Trianguli, BD+33° 395, Gliese 92, HD 13974, HIP 10644, HR 660, LHS 154, LTT 10770, SAO 55420.[11]
Database references

Delta Trianguli (Delta Tri, δ Trianguli, δ Tri) is a spectroscopic binary star system approximately 35 light-years (11 pc) away in the constellation of Triangulum. The primary star is a yellow dwarf, while the secondary star is thought to be an orange dwarf. It has an apparent magnitude of +4.87 and forms an optical (line-of-sight) triple with Gamma Trianguli and 7 Trianguli.[6]

Stellar components[edit]

Delta Trianguli A is a main sequence star with a stellar classification of G0V and a mass similar to the Sun.[6] The spectral characteristics of the smaller companion Delta Trianguli B are not well determined since the close orbit makes observations difficult,[12] with estimates of the spectral class ranging from G9V to K4V.[3] The Delta Trianguli stars orbit their center of mass with an estimated separation of 0.106 AU;[6] it is certainly less than one AU.[3] The orbital period is 10.02 days and the eccentricity of the orbit is only 0.020. The orbit is inclined about 167° to humans' line of sight.[10]

A 2008 search for a tertiary companion to this system using an adaptive optics system on the VLT proved unsuccessful.[13] Examination of the system in infrared light at 70 μm shows no excess emission that would otherwise indicate the presence of a disk of orbiting dust.[3]


In Chinese, 天大將軍 (Tiān Dà Jiāng Jūn), meaning Heaven's Great General, refers to an asterism consisting of δ Trianguli γ Andromedae, φ Persei, 51 Andromedae, 49 Andromedae, χ Andromedae, υ Andromedae, τ Andromedae, 56 Andromedae, β Trianguli and γ Trianguli. Consequently, δ Trianguli itself is known as 天大將軍十一 (Tiān Dà Jiāng Jūn shíyī, English: the Eleventh Star of Heaven's Great General.).[14]

See also[edit]


  1. ^ a b c d e van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. Bibcode:2007A&A...474..653V. arXiv:0708.1752Freely accessible. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Nordström, B.; et al. (May 2004), "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs", Astronomy and Astrophysics, 418: 989–1019, Bibcode:2004A&A...418..989N, arXiv:astro-ph/0405198Freely accessible, doi:10.1051/0004-6361:20035959 
  3. ^ a b c d e Kim, Jinyoung Serena; et al. (October 2005), "Formation and Evolution of Planetary Systems: Cold Outer Disks Associated with Sun-like Stars", The Astrophysical Journal, 632 (1): 659–669, Bibcode:2005ApJ...632..659K, arXiv:astro-ph/0506434Freely accessible, doi:10.1086/432863 
  4. ^ a b Johnson, H. L.; Iriarte, B.; Mitchell, R. I.; Wisniewskj, W. Z. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J 
  5. ^ a b White, Russel J.; et al. (June 2007), "High-Dispersion Optical Spectra of Nearby Stars Younger Than the Sun", The Astronomical Journal, 133 (6): 2524–2536, Bibcode:2007AJ....133.2524W, arXiv:0706.0542Freely accessible, doi:10.1086/514336 
  6. ^ a b c d Kaler, James, "Delta Tri", Stars: Portraits of Stars and their Constellations, University of Illinois, retrieved 2011-09-16 
  7. ^ Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367: 5211–524, Bibcode:2001A&A...367..521P, arXiv:astro-ph/0012289Freely accessible, doi:10.1051/0004-6361:20000451 
  8. ^ a b Clegg, R. E. S. (October 1977), "Carbon and nitrogen abundances in F- and G-type stars", Monthly Notices of the Royal Astronomical Society, 181: 1–30, Bibcode:1977MNRAS.181....1C, doi:10.1093/mnras/181.1.1 
  9. ^ Holmberg, J.; Nordström, B.; Andersen, J. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, Bibcode:2009A&A...501..941H, arXiv:0811.3982Freely accessible, doi:10.1051/0004-6361/200811191 
  10. ^ a b "Sixth Catalog of Orbits of Visual Binary Stars", U.S. Naval Observatory, retrieved 2008-06-22 
  11. ^ "del Tri -- Spectroscopic binary", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2011-09-16 
  12. ^ Raghavan, Deepak; et al. (September 2010), "A Survey of Stellar Families: Multiplicity of Solar-type Stars", The Astrophysical Journal Supplement, 190 (1): 1–42, Bibcode:2010ApJS..190....1R, arXiv:1007.0414Freely accessible, doi:10.1088/0067-0049/190/1/1 
  13. ^ Tokovinin, A.; et al. (May 2006), "Tertiary companions to close spectroscopic binaries", Astronomy and Astrophysics, 450 (2): 6811–693, Bibcode:2006A&A...450..681T, arXiv:astro-ph/0601518Freely accessible, doi:10.1051/0004-6361:20054427 
  14. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 10 日

External links[edit]