Delta Trianguli

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]

Delta Trianguli

Location of δ Trianguli (circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Triangulum
Right ascension	02^h 17^m 03.23016^s[1]
Declination	+34° 13′ 27.2260″[1]
Apparent magnitude (V)	+4.865[2]
Characteristics
Spectral type	G0V / G9V to K4V[3]
U−B color index	+0.02[4]
B−V color index	+0.61[4]
Astrometry
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]
Details
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
Orbit[10]
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
SIMBAD	data

Stellar components

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]

Naming

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, the Chinese name for δ Trianguli itself is 天大將軍十一 (Tiān Dà Jiāng Jūn shíyī, English: the Eleventh Star of Heaven's Great General.).[14]

See also

• V4046 Sagittarii

References

1. van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
2. 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, arXiv:astro-ph/0405198, Bibcode:2004A&A...418..989N, doi:10.1051/0004-6361:20035959
3. 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, arXiv:astro-ph/0506434, Bibcode:2005ApJ...632..659K, doi:10.1086/432863
4. 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. 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, arXiv:0706.0542, Bibcode:2007AJ....133.2524W, doi:10.1086/514336
6. 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, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451
8. 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, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191
10. "Sixth Catalog of Orbits of Visual Binary Stars", U.S. Naval Observatory, archived from the original on 2009-04-12, 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, arXiv:1007.0414, Bibcode:2010ApJS..190....1R, 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, arXiv:astro-ph/0601518, Bibcode:2006A&A...450..681T, doi:10.1051/0004-6361:20054427
14. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 10 日

External links

• "Delta Trianguli 2". SolStation. Retrieved 2008-06-22.