TW Hydrae b
| Exoplanet | List of exoplanets | |
|---|---|---|
| [[Image:|300px]] |
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| Parent star | ||
| Star | TW Hydrae | |
| Constellation | Hydra | |
| Right ascension | (α) | 11h 01m 52s |
| Declination | (δ) | −34° 42′ 17″ |
| Apparent magnitude | (mV) | 11.72 |
| Distance | 176.245 ly (54 ± 5 pc) |
|
| Spectral type | K6 (PMS) | |
| Mass | (m) | 0.8 M☉ |
| Radius | (r) | 1.1 R☉ |
| Temperature | (T) | 4000 K |
| Age | 0.008 Gyr | |
| Physical characteristics | ||
| Mass | (m) | 23.72M⊕ |
| Radius | (r) | ~4.25 R⊕ |
| Temperature | (T) | ≥40 K (−233.2 °C; −387.7 °F) |
| Orbital elements | ||
| Semi-major axis | (a) | 22 AU |
| Discovery information | ||
| Discovery date | First: December 2007 (disproven) New study: September 2016 |
|
| Discoverer(s) | First: Setiawan et al. New study: Atacama Large Millimeter Array |
|
| Discovery site | First:  GermanyNew study:  Chile
|
|
| Discovery status | First: Disputed New study: Likely |
|
TW Hydrae b is a likely extrasolar planet orbiting the young T Tauri star TW Hydrae approximately 176 light-years (54 parsecs, or nearly 1.665×1016 km) away in the constellation of Hydra. It is likely a Neptune-like planet orbiting at a distance of nearly 22 AU from its star.
TW Hydrae b is an ice giant, an exoplanet with a radius and mass close to that of the ice giants Neptune and Uranus. It may have an equilibrium temperature of around 40 K (−233.2 °C; −387.7 °F). It has an estimated mass of around 22.72 M⊕ (or 1.5 MNeptune) and a possible radius of 4.25 R⊕.
The planet orbits a (K-type) T Tauri star named TW Hydrae. The star has a mass of 0.8 M☉ and a radius of 1.1 R☉. It has a temperature of 4000 K and is about 9 million years old. In comparison, the Sun is 4.6 billion years old and has a temperature of 5778 K. It's luminosity (L☉) is 28% of that of the Sun.
The star's apparent magnitude, or how bright it appears from Earth's perspective, is 11.27. Therefore, it is too dim to be seen with the naked eye.
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Wikipedia