Epsilon Trianguli

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]

ε Trianguli

Location of ε Trianguli (circled)
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]