  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Triangulum |
| Right ascension | 02h 17m 18.86703s[1] |
| Declination | +33° 50′ 49.8950″[1] |
| Apparent magnitude (V) | +4.01[2] |
| Characteristics | |
| Spectral type | A1Vnn[3] |
| U−Bcolor index | +0.02[2] |
| B−Vcolor index | +0.02[2] |
| Astrometry | |
| Radial velocity (Rv) | +9.9[4] km/s |
| Proper motion (μ) | RA: 44.64[1]mas/yr Dec.: –52.57[1]mas/yr |
| Parallax (π) | 29.04±0.25 mas[1] |
| Distance | 112.3 ± 1.0 ly (34.4 ± 0.3 pc) |
| Absolute magnitude (MV) | +1.35[5] |
| Details | |
| Mass | 2.7[6] M☉ |
| Radius | 2.09±0.04[7] R☉ |
| Luminosity | 28±1[7] L☉ |
| Temperature | 9,210±100[7] K |
| Rotational velocity (v sin i) | 254[8] km/s |
| Age | 300[6] Myr |
| Other designations | |
| Apdu,γ Tri,9 Tri,BD+33 397,FK5 79,HD 14055,HIP 10670,HR 664,SAO 55427[9] | |
| Database references | |
| SIMBAD | data |
Gamma Trianguli, also namedApdu,[10] is astar in theconstellationTriangulum located approximately 112light years fromEarth. It has anapparent magnitude of +4.01 and forms an optical (line-of-sight) triple withDelta Trianguli and7 Trianguli.[11]
Gamma Trianguli (Latinized fromGamma Tri, abbreviatedγ Trianguli,γ Tri) is the star'sBayer designation.
This star was part of the ancient Egyptian constellation Apdu, the Bird, which is identified with the area betweenAlgol and Triangulum. TheIAU Working Group on Star Names approved the name Apdu for this star on 13 November 2025 and it is now so entered in the IAU Catalog of Star Names.[10]
InChinese,天大將軍 (Tiān Dà Jiāng Jūn), meaningHeaven's Great General, refers to an asterism consisting of γ Trianguli,γ Andromedae,φ Persei,51 Andromedae,49 Andromedae,χ Andromedae,υ Andromedae,τ Andromedae,56 Andromedae,β Trianguli, andδ Trianguli. Consequently, theChinese name for γ Trianguli itself is天大將軍十 (Tiān Dà Jiāng Jūn shí, English:the Tenth Star of Heaven's Great General).[12]
This star has astellar classification of A1Vnn,[3] which indicates it is anA-type main sequence star. It has 2.7 times the mass of the Sun[6] and 2.09 times Sun's radius.[7] Gamma Trianguli is radiating about 33 times the luminosity of the Sun from its outer envelope[6] at aneffective temperature of 9,210 K,[7] giving the star a white hue.[13] The star is roughly 300 million years old.[6]
It is rotating rapidly, with aprojected rotational velocity of 254 km/s along the equator,[8] which causes the star to take the pronounced shape of anoblate spheroid likeAltair.[11] Because the inclination of the star'saxial tilt is unknown, this means that the azimuthal equatorial velocity is at least this amount and possibly higher.[8] By comparison, the Sun is a slow rotator with an equatorial azimuthal velocity of 2 km/s.[14] Thedoppler shift from the rapid rotation results in very diffuseabsorption lines in the star's spectrum, as indicated by the 'nn' in the classification.[15]
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Orbiting the star is a dustydebris disk with a combined mass of about2.9 × 10−2 times the mass of theEarth. This disk can be detected because it is being heated to a temperature of about 75 K by Gamma Trianguli and is radiating this as infrared energy. The disk is separated from the host star by an angle of 2.24 arcseconds, corresponding to a physical radius of 80 AU, or 80 times the separation of the Earth from the Sun.[16]
| Disks (in order from star) | Radius (AU) | Inclination |
|---|---|---|
| circumstellar disc | 180±10 | 81.1+0.8 −0.9° |
