TW Hydrae
TW Hydrae is a T Tauri star approximately 196 light-years away in the constellation of Hydra (the Sea Serpent). TW Hydrae is about 80% of the mass of the Sun, but is only about 5-10 million years old. The star appears to be accreting from a face-on protoplanetary disk of dust and gas, which has been resolved in images from the ALMA observatory. TW Hydrae is accompanied by about twenty other low-mass stars with similar ages and spatial motions, comprising the "TW Hydrae association" or TWA, one of the closest regions of recent "fossil" star-formation to the Sun.
Inner region of TW Hydrae protoplanetary disc Credit: S. Andrews, B. Saxton, ALMA (see description) | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Hydra |
| Right ascension | 11h 01m 51.9054s |
| Declination | −34° 42′ 17.0316″> |
| Apparent magnitude (V) | 11.27 ± 0.09 |
| Characteristics | |
| Evolutionary stage | Pre-main-sequence |
| Spectral type | K6 |
| U−B color index | -0.33 |
| B−V color index | 0.67 |
| J−H color index | 0.659 |
| J−K color index | 0.92 |
| Variable type | T Tauri |
| Astrometry | |
| Radial velocity (Rv) | 13.40 ± 0.8 km/s |
| Proper motion (μ) | RA: −68.389 ± 0.054 mas/yr Dec.: −14.016 ± 0.059 mas/yr |
| Parallax (π) | 16.6428 ± 0.0416 mas |
| Distance | 196.0 ± 0.5 ly (60.1 ± 0.2 pc) |
| Details | |
| Mass | 0.8 M☉ |
| Radius | 1.11 R☉ |
| Luminosity (bolometric) | 0.28 L☉ |
| Temperature | 4,000 K |
| Age | 8 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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