Delta Trianguli
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| Observation data Epoch J2000.0 Equinox J2000.0 |
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|---|---|
| Constellation | Triangulum |
| Right ascension | 02h 17m 03.23016s |
| Declination | +34° 13′ 27.2260″ |
| Apparent magnitude (V) | +4.865 |
| Characteristics | |
| Spectral type | G0V / G9V to K4V |
| U−B color index | +0.02 |
| B−V color index | +0.61 |
| Astrometry | |
| Radial velocity (Rv) | −5.70 km/s |
| Proper motion (μ) |
RA: 1151.83 mas/yr Dec.: −246.89 mas/yr |
| Parallax (π) | 92.73 ± 0.39mas |
| Distance | 35.2 ± 0.1 ly (10.78 ± 0.05 pc) |
| Absolute magnitude (MV) | 4.69 |
| Details | |
| Mass | 1.0/0.8 M☉ |
| Radius | 0.98 R☉ |
| Surface gravity (log g) | 4.5 cgs |
| Temperature | 6,215/4,493 K |
| Metallicity [Fe/H] | −0.39 to −0.30 dex |
| Rotational velocity (v sin i) | 10.00 km/s |
| Age | 8.5 to 9.0 Gyr |
| Orbit | |
| 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 | |
| Database references | |
| SIMBAD | data |
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.
Delta Trianguli A is a main sequence star with a stellar classification of G0V and a mass similar to the Sun. The spectral characteristics of the smaller companion Delta Trianguli B are not well determined since the close orbit makes observations difficult, with estimates of the spectral class ranging from G9V to K4V. The Delta Trianguli stars orbit their center of mass with an estimated separation of 0.106 AU; it is certainly less than one AU. 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.
A 2008 search for a tertiary companion to this system using an adaptive optics system on the VLT proved unsuccessful. 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.
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.).
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