T Tauri
T Tauri is a variable star in the constellation Taurus, the prototype of the T Tauri stars. It was discovered in October 1852 by John Russell Hind. T Tauri appears from Earth amongst the Hyades cluster, not far from ε Tauri, but it is actually 420 light-years behind it and not a member of the cluster. The cloud to the west of the system is NGC 1555, known more commonly as Hind's Variable Nebula.
The star T Tauri with NGC 1555 cloud nearby. | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Taurus |
| Right ascension | 04h 21m 59.43445s |
| Declination | +19° 32′ 06.4182″ |
| Apparent magnitude (V) | 10.27 |
| Characteristics | |
| Spectral type | G5V:e |
| U−B color index | +0.80 |
| B−V color index | +1.22 |
| Variable type | T Tauri |
| Astrometry | |
| Radial velocity (Rv) | +24.6 km/s |
| Proper motion (μ) | RA: +15.51 mas/yr Dec.: -13.67 mas/yr |
| Parallax (π) | 6.9290 ± 0.0583 mas |
| Distance | 471 ± 4 ly (144 ± 1 pc) |
| Orbit | |
| Primary | T Tau N |
| Companion | T Tau S |
| Period (P) | 4200+5000 −3400 yr |
| Semi-major axis (a) | 2.9+5.4 −1.7″ |
| Eccentricity (e) | 0.7+0.2 −0.4 |
| Inclination (i) | 52+4 −5° |
| Longitude of the node (Ω) | 156 ± 11° |
| Periastron epoch (T) | B 1967+25 −47 |
| Argument of periastron (ω) (secondary) | 48+34 −25° |
| Orbit | |
| Primary | T Tau Sa |
| Companion | T Tau Sb |
| Period (P) | 27 ± 2 yr |
| Semi-major axis (a) | 85+4 −2 mas |
| Eccentricity (e) | 0.56+0.07 −0.09 |
| Inclination (i) | 20+10 −6° |
| Longitude of the node (Ω) | 92+26 −36° |
| Periastron epoch (T) | JD 2450131+208 −288 (1996 Feb 17) |
| Argument of periastron (ω) (secondary) | 48+34 −25° |
| Details | |
| T Tau Sa | |
| Mass | 2.12 ± 0.10 M☉ |
| Age | 0.4 Myr |
| T Tau Sb | |
| Mass | 0.53 ± 0.06 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
Although this system is considered to be the prototype of T Tauri stars, a later phase in a protostar's formation, it is a very atypical T Tauri star.
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