Alpha Trianguli
  | |
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Triangulum |
| A | |
| Right ascension | 01h 53m 04.90710s |
| Declination | +29° 34′ 43.7801″ |
| Apparent magnitude (V) | +3.42 |
| C | |
| Right ascension | 01h 53m 01.04815s |
| Declination | +29° 37′ 03.9309″ |
| Characteristics | |
| A | |
| Evolutionary stage | main sequence |
| Spectral type | F5III to F6IV + M |
| U−B color index | +0.06 |
| B−V color index | +0.48 |
| Variable type | Ellipsoidal |
| C | |
| Evolutionary stage | red dwarf |
| Astrometry | |
| A | |
| Radial velocity (Rv) | −12.6 km/s |
| Proper motion (μ) | RA: +10.82 mas/yr Dec.: −234.24 mas/yr |
| Parallax (π) | 51.50±0.23 mas |
| Distance | 63.3 ± 0.3 ly (19.42 ± 0.09 pc) |
| Absolute magnitude (MV) | 1.98 |
| C | |
| Radial velocity (Rv) | −10.42±0.42 km/s |
| Proper motion (μ) | RA: +9.922 mas/yr Dec.: −236.07 mas/yr |
| Parallax (π) | 50.4136±0.0197 mas |
| Distance | 64.70 ± 0.03 ly (19.836 ± 0.008 pc) |
| Orbit | |
| Primary | Aa |
| Name | Ab |
| Period (P) | 1.767 days |
| Eccentricity (e) | 0.065 |
| Semi-amplitude (K1) (primary) | 10.64 km/s |
| Details | |
| α Tri Aa | |
| Mass | 1.65 M☉ |
| Radius | 3.13 R☉ |
| Luminosity | 12.9 L☉ |
| Surface gravity (log g) | 3.66 cgs |
| Temperature | 6,187 K |
| Metallicity [Fe/H] | −0.09 to 0.00 dex |
| Rotational velocity (v sin i) | 81.6 km/s |
| Age | 1.7 Gyr |
| α Tri Ab | |
| Mass | 0.11 M☉ |
| Radius | 0.14 R☉ |
| α Tri C | |
| Mass | 0.403±0.013 M☉ |
| Radius | 0.406±0.012 R☉ |
| Luminosity | 0.0210±0.0006 L☉ |
| Surface gravity (log g) | 4.06±0.77 cgs |
| Temperature | 3,420±114 K |
| Metallicity [Fe/H] | −1.20±0.04 dex |
| Other designations | |
| Mothallah, Ras al Muthallah, Caput Trianguli, α Trianguli, 2 Trianguli, HR 544, HD 11443, BD+28°312, FK5 64, HIP 8796, SAO 74996 | |
| C: TIC 28244970, 2MASS J01530103+2937044 | |
| Database references | |
| SIMBAD | data |
| C | |
Alpha Trianguli (α Trianguli, abbreviated Alpha Tri, α Tri) is a triple star system in the constellation of Triangulum. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 63.3 light-years (19.4 parsecs) distant from the Sun. The brighter or primary component is named Mothallah /məˈθælə/.