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]

References

1. van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J
3. Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819
4. Wilson, Ralph Elmer (1953), "General catalogue of stellar radial velocities", Carnegie Institute Washington D.C. Publication, Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W
5. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
6. Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
7. Rhee, Joseph H.; et al. (May 2007), "Characterization of Dusty Debris Disks: The IRAS and Hipparcos Catalogs", The Astrophysical Journal, 660 (2): 1556–1571, arXiv:astro-ph/0609555, Bibcode:2007ApJ...660.1556R, doi:10.1086/509912, S2CID 11879505
8. Monier, R. (November 2005), "Abundances of a sample of A and F-type dwarf members of the Ursa Major Group", Astronomy and Astrophysics, 442 (2): 563–566, Bibcode:2005A&A...442..563M, doi:10.1051/0004-6361:20053222
9. Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID 18475298
10. "eps Tri -- Variable Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2011-12-13
11. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
12. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976
13. King, Jeremy R.; et al. (April 2003), "Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group", The Astronomical Journal, 125 (4): 1980–2017, Bibcode:2003AJ....125.1980K, doi:10.1086/368241