NASA (Exoplanet Catalog artwork)Gliese 436 b
A hot Neptune trailing a giant cloud of hydrogen
Overview
Gliese 436 b is a Neptune-sized exoplanet orbiting the red dwarf Gliese 436 (Noquisi), the only known planet in its system. It was the first hot Neptune discovered with certainty and was among the smallest-known transiting planets in mass and radius, until the much smaller Kepler exoplanet discoveries began circa 2010.
Source: Wikipedia
NASA: GJ 436 b is a Neptune-like exoplanet that orbits a M-type star. Its mass is 22.1 Earths, it takes 2.6 days to complete one orbit of its star, and is 0.0291 AU from its star. Its discovery was announced in 2004.
Why it matters
- Hubble found a comet-like hydrogen cloud 50 times the planet's size streaming behind it in 2015.
- Orbits over its star's poles on an unexpectedly eccentric 2.6-day orbit.
- Its atmosphere is strangely poor in methane and rich in carbon monoxide.
NASA puts it this way: “A close exoplanet with a secret: a lack of methane on this hot world. GJ 436 b is a Neptune-sized exoplanet that orbits an M-type star. Its mass is 22.1 Earths,”
Discovery & system
- Discovered
- 2004 · Radial Velocity · W. M. Keck Observatory
- Discovery paper
- Butler et al. 2004
- Discoverers
- Geoffrey Marcy
- Host star
- GJ 436 · M2.5 V · 3,586 K · 0.47 M☉
- System
- 1 known planet
The system
| World | Period | Distance | Radius | Mass | Temp. |
|---|---|---|---|---|---|
| GJ 436 b | 2.64 d | 0.029 AU | 0.37 R♃ | 22.1 M⊕ | 686 K |
By the numbers
- Radius
- 0.37 R♃4.2 R⊕
- Mass
- 22.1 M⊕131.99 ×10²⁴ kg
- Orbital period
- 2.64 d0.01 yr
- Distance from star
- 0.029 AU4.35 million km
- Eccentricity
- 0.138elliptical
- Equilibrium temp.
- 686 K413 °C
- Starlight received
- 29 × Earth
- Distance from Earth
- 31.8 ly9.8 pc
- Density
- 1.8 g/cm³0.33 × Earth
Sources
Image: NASA (Exoplanet Catalog artwork) · NASA media: generally free of copyright · image page
Text: Wikipedia (CC BY-SA 4.0). Taglines and highlights are editorial.