R Trianguli
R Trianguli (abbreviated as R Tri) is a short-period oxygen-rich Mira variable in Triangulum with a period of 266.9 days, discovered by T. H. E. C. Espin in 1890. It is losing about 1.1×10−7 M☉/yr, close to average for a short-period Mira variable. While most short-period Mira variables reside in the Galactic halo, R Trianguli is a member of the thick disk, and its proper motion is fairly high for its distance. Its angular diameter in the K band was measured in 2002 to be, on average, 5.22±0.30 mas, with a shape suggesting that there is an optically thin disk structure surrounding the star.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Triangulum |
| Right ascension | 02h 37m 02.340s |
| Declination | +34° 15′ 51.34″ |
| Apparent magnitude (V) | 5.4–12.6 |
| Characteristics | |
| Spectral type | M3.5-8IIIe |
| Apparent magnitude (B) | 8.524±0.018 |
| Apparent magnitude (G) | 6.699±0.055 |
| Apparent magnitude (R) | 8.24 |
| Apparent magnitude (J) | 2.23±0.27 |
| Apparent magnitude (H) | 1.36±0.22 |
| Apparent magnitude (K) | 1.05±0.21 |
| Variable type | Mira |
| Astrometry | |
| Radial velocity (Rv) | 67.52±0.88 km/s |
| Proper motion (μ) | RA: +34.272 mas/yr Dec.: −10.683 mas/yr |
| Parallax (π) | 2.4334 ± 0.2487 mas |
| Distance | approx. 1,300 ly (approx. 410 pc) |
| Details | |
| Mass | 1.71 M☉ |
| Radius | 196±41 R☉ |
| Luminosity | 1,784 L☉ |
| Surface gravity (log g) | −0.09 cgs |
| Temperature | 3184±120 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
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