Beta Trianguli

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Binary star in the constellation Triangulum

title: "Beta Trianguli" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["bayer-objects", "flamsteed-objects", "triangulum", "bright-star-catalogue-objects", "henry-draper-catalogue-objects", "hipparcos-objects", "durchmusterung-objects", "a-type-subgiants", "spectroscopic-binaries", "lucidae", "stars-with-proper-names"] description: "Binary star in the constellation Triangulum" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Beta_Trianguli" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Binary star in the constellation Triangulum ::

| name = β Trianguli | image= |image=Triangulum constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=12|mark_link=β Trianguli |x=517|y=319 |caption=Location of β Trianguli (circled) | epoch = J2000.0 | constell = Triangulum | ra = | dec = | appmag_v = +3.00 (3.44 + 4.19) | class = A8III / A3III | b-v = +0.21 / 0.07 | u-b = +0.11 | variable = | radial_v = +9.9 | prop_mo_ra = 149.16 | prop_mo_dec = –39.10 | parallax = 23.169 | p_error = 0.434 | parallax_footnote = | absmag_v = (0.305 + 0.1055) | reference = | period_unitless = 31.3884 d | axis_unitless = | eccentricity = 0.53 | periastron = 2432004.255 JD | periarg = 318.4 | k1 = 33.3 | k2 = 69.2 | source = | component1 = A | mass = | radius = | luminosity = | temperature = 7,683 | gravity = 3.70 | metal_fe = | rotational_velocity = 70 | age_gyr = | component2 = B | mass2 = | radius2 = | luminosity2 = | temperature2 = 8,759 | age_gyr2 = | names = | Simbad = bet+Tri

Beta Trianguli, formally named Alaybasan (for component A), is a binary star system in the constellation Triangulum, located about 127 light years from Earth. Although it is only a third-magnitude star, it is the brightest star in the constellation Triangulum.

Naming

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

This star together with α Trianguli were called by the Arabic names Al Mīzān, "the Scale Beam", and Al-Aybasān, "the Two Joints [of Aries]"; the latter also written as Al-Anīsān, meaning "the Two Friends". Mizan has been used as a name for β Trianguli. The name Alaybasan was approved for Beta Trianguli A by the IAU Working Group on Star Names on 7 November 2025 and it is now so entered in the IAU Catalog of Star Names.

In Chinese, 天大將軍 (Tiān Dà Jiāng Jūn), meaning Heaven's Great General, refers to an asterism consisting of β Trianguli, γ Andromedae, φ Persei, 51 Andromedae, 49 Andromedae, χ Andromedae, υ Andromedae, τ Andromedae, 56 Andromedae, γ Trianguli and δ Trianguli. Consequently, the Chinese name for β Trianguli itself is 天大將軍九 (Tiān Dà Jiāng Jūn jiǔ, ).

Star system

This is a double-lined spectroscopic binary star system with an orbital period of 31.39 days and an eccentricity of 0.53. The members are separated by a distance of . The primary and secondary components have stellar classifications of A8III and A3III respectively, indicating that they evolved away from the main sequence and are now giant stars. Component A is 2.6 times more massive than the Sun, but expanded to the Sun's radius and irradiates 60 times more than the Sun. Component B is somewhat smaller and less luminous, being 2.25 times more massive, times larger and 30 times brighter than the Sun. The system has an age around 400 million years, less than 10% that of the Solar System. Beta Trianguli is among the least variable of the stars that were observed by the Hipparcos spacecraft, with a magnitude varying by only 0.0005.

Based on observations using the Spitzer Space Telescope, as reported in 2005, this system is emitting an excess of infrared radiation. This emission can be explained by a circumbinary ring of dust. The dust is emitting infrared radiation at a blackbody temperature of 100 K.

Notes

= 4.38\ R_\odot.}}

= 2.44\ R_\odot.}}

References

References

  1. (2004). "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits". Astronomy & Astrophysics.
  2. (2003). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I". The Astronomical Journal.
  3. {{in lang. zh [http://aeea.nmns.edu.tw/2006/0607/ap060710.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 10 日] {{Webarchive. link. (2011-07-16)
  4. (2012). "Coplanar Circumbinary Debris Disks". [[Monthly Notices of the Royal Astronomical Society]].
  5. (2020-02-01). "A study of the physical properties of SB2s with both the visual and spectroscopic orbits". Monthly Notices of the Royal Astronomical Society.
  6. Groenewegen, M. A. T.. (2023-01-01). "Orbital parallax of binary systems compared to Gaia DR3 and the parallax zero-point offset at bright magnitudes". Astronomy and Astrophysics.
  7. van Leeuwen, F.. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics.
  8. Wilson, Ralph Elmer. (1953). "General catalogue of stellar radial velocities". [[Carnegie Institution of Washington]].
  9. (October 2002). "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i". Astronomy and Astrophysics.
  10. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory.
  11. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society.
  12. (1997). "Star-Hopping: Your Visa to Viewing the Universe". [[Cambridge University Press]].
  13. "bet Tri -- Spectroscopic binary". [[Centre de Données astronomiques de Strasbourg]].
  14. (February 2001). "Research Note Hipparcos photometry: The least variable stars". Astronomy and Astrophysics.
  15. (2005). "Protostars and Planets V, Proceedings of the Conference held October 24-28, 2005, in Hilton Waikoloa Village, Hawai'i".
  16. "Alaybasān (الأيبسان)". [[IAU Working Group on Star Names]].
  17. "IAU Catalog of Star Names".

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bayer-objectsflamsteed-objectstriangulumbright-star-catalogue-objectshenry-draper-catalogue-objectshipparcos-objectsdurchmusterung-objectsa-type-subgiantsspectroscopic-binarieslucidaestars-with-proper-names