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Location of β Trianguli (circled) |
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| Observation data Epoch J2000.0 Equinox J2000.0 |
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|---|---|
| Constellation | Triangulum |
| Right ascension | 02h 09m 32.62712s[1] |
| Declination | +34° 59′ 14.2694″[1] |
| Apparent magnitude (V) | +3.00[2] |
| Characteristics | |
| Spectral type | A5III[3] |
| U−B color index | +0.11[2] |
| B−V color index | +0.14[2] |
| Astrometry | |
| Radial velocity (Rv) | +9.9[4] km/s |
| Proper motion (μ) | RA: 149.16[1] mas/yr Dec.: –39.10[1] mas/yr |
| Parallax (π) | 25.71 ± 0.34[1] mas |
| Distance | 127 ± 2 ly (38.9 ± 0.5 pc) |
| Details | |
| Rotational velocity (v sin i) | 70[5] km/s |
| Other designations | |
Beta Trianguli (β Trianguli, β Tri) is a binary star system in the constellation Triangulum, located about 127 light years from Earth.[1] Although the apparent magnitude is only 3.0,[2] it is the brightest star in the constellation Triangulum.[7] In combination with Alpha Trianguli, these stars were called Al Mīzān, which is Arabic for "The Scale Beam".[7] In Chinese traditional astronomy, it was the 9th star of Tien Ta Tseang (天大將軍九).[8]
The star Beta Trianguli has a stellar classification of A5III, indicating that it has evolved away from the main sequence and is now a giant star. It is among the least variable of the stars that were observed by the Hipparcos spacecraft, with a magnitude varying by only 0.0005.[9] This is a probable spectroscopic binary star system with an orbital period of 31.39 days and an eccentricity of 0.43.[10] They are separated by a distance of less than 5 AU.[11]
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 orbiting at a distance of about 10–20 AU from the stars. The dust is emitting infrared radiation at a blackbody temperature of 100 K.[11]
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