Exoplanetary Scratchpad

[SysBP Img]

The second known red dwarf planetary system. Contains one of the first Neptunians discovered. Planet b temporarily later found to be the smallest exoplanet (about Uranus' diameter, though over 50% its mass) known to transit its host star and is currently the nearest (33 ly). Its temperature (712K) was measured to be higher than what it would be purely from radiation (520K), perhaps due to a greenhouse effect, somewhat higher than Venus. It was originally thought to have a layer of "hot ice", water solidified due to high pressures. It turned out that it was larger than thought and hot ice was not needed. It could still be a rocky super-Earth. It was later found to have a remarkably low levels of Methane and high levels of Carbon Monoxide for its 800K temperature. Possible explanations include Methane being changed into hydrocarbon polymers due to its star's ultraviolet radiation, CO being drafted upwards with winds, or observational defects. It's significant eccentricity suggests a possible neighboring planet. Planet c was announced to be the smallest known exoplanet (1.5 Earth's diameter), but was later retracted because variations in transit timing of the first planet did not occur and the proposed orbit would be unstable. It is still thought that a second planet of some kind is possible in the system.

Gliese 436 System Web Pages

Gliese 436 System Artwork

  • Painting of planet b after discovery.
  • Possible sizes when discovered.
  • Possible terminator habitable zone (obsolete).
  • Illustration of terminator HZ.
  • Artwork of planet and transit.
  • Interior diagram of planet.

Gliese 436 System In the News

Neptunian Planet b Discovered (Sep 2004)

The second/third Neptunian is detected (along with 55 Cancri e, making Gliese 436 the second known red dwarf to harbor planets.

Controversy Over First Neptunian Discovered (Sep 2004)

Planet Made of "Hot Ice" (May 2007)

Planet b becomes the smallest exoplanet known to transit its host star and the nearest. It has been characterized by having a steamy atmosphere and "hot ice".

New Spitzer Radius Measurements (Jul 2007)

Spitzer Transit and Secondary Eclipse Photometry (Jul 2007)

Superearth Planet Suspected (Jan 2008)

New Hubble Transit Light Curve (Apr 2008)

Planet c Confirmed (Apr 2008)

Planet c Retracted (May 2008)

Low Levels of Methane and High Levels of Carbon Monoxide Detected (Apr 2010)

Still Puzzling over Low Methane Level (Sep 2010)

Alien Planets with No Spin May be Too Harsh for Life (Dec 2011)

Gliese 436 System Fun Links

  • article - Is the planet Republican or Democrat?