Gamma Trianguli

Last updated
γ Trianguli
Triangulum constellation map.svg
Red circle.svg
Location of γ Trianguli (circled)
Observation data
Epoch J2000       Equinox J2000
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  mas [1]
Distance 112.3 ± 1.0  ly
(34.4 ± 0.3  pc)
Absolute magnitude  (MV)+1.35 [5]
Details
Mass 2.7 [6]   M☉
Radius 1.96 [7]   R☉
Luminosity 33.0 [6]   L☉
Temperature 9,440 [8]   K
Rotational velocity (v sin i)254 [9]  km/s
Age 300 [6]   Myr
Other designations
Apdu, γ Tri, 9 Tri, BD+33 397, FK5 79, HD 14055, HIP 10670, HR 664, SAO 55427 [10]
Database references
SIMBAD data

Gamma Trianguli, also named Apdu, [11] is a star in the constellation Triangulum located approximately 112 light years from Earth. It has an apparent magnitude of +4.01 and forms an optical (line-of-sight) triple with Delta Trianguli and 7 Trianguli. [12]

Contents

Naming

Gamma Trianguli (Latinized from Gamma Tri, abbreviated γ Trianguli, γ Tri) is the star's Bayer designation.

This star was part of the ancient Egyptian constellation Apdu, the Bird, which is identified with the area between Algol and Triangulum. The IAU Working Group on Star Names approved the name Apdu for this star on 13 November 2025 and it is now so entered in the IAU Catalog of Star Names. [11]

In Chinese, 天大將軍 (Tiān Dà Jiāng Jūn), meaning Heaven's Great General , refers to an asterism consisting of γ Trianguli, γ Andromedae, φ Persei, 51 Andromedae, 49 Andromedae, χ Andromedae, υ Andromedae, τ Andromedae, 56 Andromedae, β Trianguli, and δ Trianguli. Consequently, the Chinese name for γ Trianguli itself is 天大將軍十 (Tiān Dà Jiāng Jūn shí, English: the Tenth Star of Heaven's Great General). [13]

Properties

This star has a stellar classification of A1Vnn, [3] which indicates it is an A-type main sequence star. It has 2.7 [6] times the mass of the Sun and nearly double the Sun's radius. [7] Gamma Trianguli is radiating about 33 [6] times the luminosity of the Sun from its outer envelope at an effective temperature of 9,440 K, [8] giving the star a white hue. [14] The star is roughly 300 million years old. [6]

Rotation

It is rotating rapidly, with a projected rotational velocity of 254 km/s along the equator, [9] which causes the star to take the pronounced shape of an oblate spheroid like Altair. [12] 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. [9] By comparison, the Sun is a slow rotator with an equatorial azimuthal velocity of 2 km/s. [15] 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. [16]

Debris disk

The 74 exocomet belts imaged by ALMA's REASONS survey, showing belts of all shapes, sizes and ages (REASONS comboplot full nonames).jpg
Image of the debris disk with the REASONS survey [17]

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. [7]

The Gamma Trianguli planetary system [17]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
circumstellar disc180±10 AU 81.1+0.8
−0.9 ° 		—

References

  1. 1 2 3 4 5 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, S2CID   18759600 Note: see VizieR catalogue I/311.
  2. 1 2 3 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. 1 2 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. ↑ Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg, 35, Veröffentlichungen des Astronomisches Rechen-Institut Heidelberg: 1, Bibcode:1999VeARI..35....1W
  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. 1 2 3 4 5 6 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, S2CID   18883195
  7. 1 2 3 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, S2CID   11879505
  8. 1 2 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, arXiv: 0903.5134 , Bibcode:2009A&A...501..297Z, doi:10.1051/0004-6361/200811147, S2CID   14969137
  9. 1 2 3 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. ↑ "gam Tri -- Star", SIMBAD, Centre de Données astronomiques de Strasbourg , retrieved 2011-12-11
  11. 1 2 "IAU Catalog of Star Names" . Retrieved 13 November 2025.
  12. 1 2 Kaler, James B., "GAMMA TRI (Gamma Trianguli)", Stars, University of Illinois , retrieved 2011-12-11
  13. ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 10 日 Archived 2011-07-16 at the Wayback Machine
  14. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2012-03-18, retrieved 2012-01-16
  15. ↑ Stix, Michael (2004), The sun: an introduction, Astronomy and astrophysics library (2nd ed.), Springer, p. 423, ISBN   3-540-20741-4
  16. ↑ Kaler, James B. (2011), Stars and Their Spectra: An Introduction to the Spectral Sequence (2nd ed.), Cambridge University Press, p. 88, ISBN   978-0-521-89954-3
  17. 1 2 Matrà, L.; Marino, S.; Wilner, D. J.; Kennedy, G. M.; Booth, M.; Krivov, A. V.; Williams, J. P.; Hughes, A. M.; Burgo, C. del (2025-01-15). "REsolved ALMA and SMA Observations of Nearby Stars (REASONS): A population of 74 resolved planetesimal belts at millimetre wavelengths". Astronomy and Astrophysics. 693. arXiv: 2501.09058 . Bibcode:2025A&A...693A.151M. doi:10.1051/0004-6361/202451397.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.