T Tauri
  | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Taurus |
| Right ascension | 04h 21m 59.43445s |
| Declination | +19° 32′ 06.4182″ |
| Apparent magnitude (V) | 9.3 - 13.5 |
| Characteristics | |
| Spectral type | K0IV/Ve |
| 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 |
| Name | T Tau S |
| Period (P) | 558+4 −5 yr |
| Semi-major axis (a) | 0.793±0.004″ |
| Eccentricity (e) | 0.0 |
| Inclination (i) | 36.8+0.8 −0.7° |
| Longitude of the node (Ω) | 136.5+0.6 −0.7° |
| Orbit | |
| Primary | T Tau Sa |
| Name | T Tau Sb |
| Period (P) | 27.29±0.40 yr |
| Semi-major axis (a) | 84.36±0.77 mas |
| Eccentricity (e) | 0.547±0.017 |
| Inclination (i) | 17.3±3.4° |
| Longitude of the node (Ω) | 95.2±16.5° |
| Periastron epoch (T) | 1995.87±0.35 |
| Argument of periastron (ω) (secondary) | 43.6±17.5° |
| Details | |
| T Tau N | |
| Mass | 2.4±0.2 M☉ |
| Radius | 2.89+0.14 −0.21 R☉ |
| Luminosity | 5.11+0.76 −0.66 L☉ |
| Temperature | 5,112+99 −97 K |
| T Tau Sa | |
| Mass | 2.09±0.05 M☉ |
| Age | 0.4 Myr |
| T Tau Sb | |
| Mass | 0.40±0.05 M☉ |
| Other designations | |
| T Tau, AG+19°341, BD+19°706, HBC 35, HD 284419, HH 355, HIP 20390, VDB 28 | |
| Database references | |
| SIMBAD | data |
T Tauri is a trinary 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 318 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.
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.