Epsilon Trianguli

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]
Distance390 ± 20 ly
(120 ± 5 pc)
Absolute magnitude (MV)+0.11[5]
Details
Mass2.75±0.05[6] M☉
Radius3.28[7] R☉
Luminosity93[6] L☉
Surface gravity (log g)3.76[8] cgs
Temperature10,000[7] K
Rotational velocity (v sin i)107[9] km/s
Age600[7] Myr
Other designations
ε Tri, 3 Tri, BD+32° 369, HD 12471, HIP 9570, HR 599, SAO 55218[10]
Database references
SIMBADdata

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]

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]

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