Gamma Trianguli
 Location of γ Trianguli (circled) |
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| Observation data Epoch J2000 Equinox J2000 |
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|---|---|
| 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−B color index | +0.02[2] |
| B−V color 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[1] mas |
| Distance | 112.3 ± 1.0 ly (34.4 ± 0.3 pc) |
| Details | |
| Mass | 2.7[5] M☉ |
| Radius | 1.96[6] R☉ |
| Luminosity | 33.0[5] L☉ |
| Temperature | 9,440[7] K |
| Rotational velocity (v sin i) | 254[8] km/s |
| Age | 3.0 × 108[5] years |
| Other designations | |
Gamma Trianguli (γ Tri, γ Trianguli) is a star in the constellation Triangulum located approximately 112 light years from Earth. It has an apparent magnitude of +4.03 and forms an optical (line-of-sight) triple with Delta Trianguli and 7 Trianguli.[10]
This star has a stellar classification of A1Vnn,[3] which indicates it is an A-type main sequence star. It has 2.7[5] times the mass of the Sun and nearly double the Sun's radius.[6] Gamma Trianguli is radiating about 33[5] times the luminosity of the Sun from its outer envelope at an effective temperature of 9,440 K,[7] giving the star a white hue.[11] The star is roughly 300 million years old.[5]
It is rotating rapidly, with a projected rotational velocity of 254 km/s along the equator,[8] which causes the star to take the pronounced shape of a oblate spheroid like Altair.[10] Because the inclination of the star's axial 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.[12] The doppler shift from the rapid rotation results in very diffuse absorption lines in the star's spectrum, as indicated by the 'nn' in the classification.[13]
Orbiting the star is a dusty debris disk with a combined mass of about 2.9 × 10–2 times the mass of the Earth. 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.[6]
[edit] References
- ^ a b c d e van Leeuwen, Floor (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, arXiv:0708.1752v1, Bibcode 2007A&A...474..653V, doi:10.1051/0004-6361:20078357 Note: see VizieR catalogue I/311.
- ^ a b c Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99), Bibcode 1966CoLPL...4...99J
- ^ a b 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
- ^ Wielen, R. et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions, 35, Veröffentlichungen des Astronomisches Rechen-Institut Heidelberg, Bibcode 1999VeARI..35....1W
- ^ a b c d e f Wyatt, M. C. et al. (July 2007), "Steady State Evolution of Debris Disks around A Stars", The Astrophysical Journal 663 (1): 365–382, arXiv:astro-ph/0703608, Bibcode 2007ApJ...663..365W, doi:10.1086/518404
- ^ a b c Rhee, Joseph H.; Song, Inseok; Zuckerman, B.; McElwain, Michael (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
- ^ a b Zorec, J. et al. (July 2009), "Fundamental parameters of B supergiants from the BCD system. I. Calibration of the (λ_1, D) parameters into Teff", Astronomy and Astrophysics 501 (1): 297–320, Bibcode 2009A&A...501..297Z, doi:10.1051/0004-6361/200811147
- ^ a b c 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
- ^ "gam Tri -- Star", SIMBAD (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=gam+Tri, retrieved 2011-12-11
- ^ a b Kaler, James B., "GAMMA TRI (Gamma Trianguli)", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/gammatri.html, retrieved 2011-12-11
- ^ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, retrieved 2012-01-16
- ^ Stix, Michael (2004), The sun: an introduction, Astronomy and astrophysics library (2nd ed.), Springer, p. 423, ISBN 3540207414, http://books.google.com/books?id=wxHN9jP-mNMC&pg=PA423
- ^ Kaler, James B. (2011), Stars and Their Spectra: An Introduction to the Spectral Sequence (2nd ed.), Cambridge University Press, p. 88, ISBN 0521899540, http://books.google.com/books?id=ZEKO2pzuRHoC&pg=PA88&lpg=PA88
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