Epsilon Trianguli
Binary star in the constellation Triangulum
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Epsilon Trianguli, Latinized from ε Trianguli, is a binary star[11] system in the northern constellation of Triangulum. Based upon measurement of its trigonometric parallax, it is approximately 390 light years from Earth.[1]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Triangulum |
| Right ascension | 02h 02m 57.95579s[1] |
| Declination | +33° 17′ 02.8813″[1] |
| Apparent magnitude (V) | +5.50[2] |
| Characteristics | |
| Spectral type | A2 V[3] |
| U−B color index | +0.06[2] |
| B−V color index | +0.03[2] |
| Astrometry | |
| Radial velocity (Rv) | 3.3[4] km/s |
| Proper motion (μ) | RA: –15.97[1] mas/yr Dec.: –7.22[1] mas/yr |
| Parallax (π) | 8.33±0.34 mas[1] |
| Distance | 390 ± 20 ly (120 ± 5 pc) |
| Absolute magnitude (MV) | +0.11[5] |
| Details | |
| Mass | 2.75±0.05[6] M☉ |
| Radius | 3.28[7] R☉ |
| Luminosity | 93[6] L☉ |
| Surface gravity (log g) | 3.76[8] cgs |
| Temperature | 10,000[7] K |
| Rotational velocity (v sin i) | 107[9] km/s |
| Age | 600[7] Myr |
| Other designations | |
| ε Tri, 3 Tri, BD+32°369, HD 12471, HIP 9570, HR 599, SAO 55218[10] | |
| Database references | |
| SIMBAD | data |
The primary component is an A-type main sequence star with a stellar classification of A2 V,[3] an apparent magnitude of +5.50 and an estimated age of 600 million years.[7] It has 2.75[6] times the mass of the Sun and is spinning with a projected rotational velocity of 107 km/s.[9] The radius of this star is more than three times the radius of the Sun, and the photosphere has an effective temperature of about 10,000.[7] The secondary component has an apparent magnitude of 11.4 and is separated from the primary by an angle of 3.9 arcseconds.[12]
An excess emission of infrared radiation suggests the presence of a dusty disk in orbit about the primary. This disk has a mean radius of 105 AU, or 105 times the separation of the Earth from the Sun, and is radiating at a temperature of 85 K.[7]
This star system is a probable member of the Ursa Major Moving Group of stars that share a common motion through space.[8] The space velocity components of Epsilon Trianguli are [U, V, W] = [+11.8, +11.4, –3.8] km/s.[13]