Wednesday, March 31, 2021

55 Cancri

55 Cancri e is an exoplanet discovered in 2004 that orbits a Sun-like star 40 light-years away from Earth.

Being so close to our planet 55 Cancri e is one of the most studied exoplanets.

55 Cancri e was discovered by the method of radial velocities, which made it possible to accurately determine its mass. The exoplanet turned out to be eight times more massive than the Earth, nearly half as massive as Neptune.

For some years it was not known whether 55 Cancri e was a mini gas giant or a Super Earth, until it was observed with the transit method, which allowed to determine its diameter (2.3 times that of the Earth) and consequently its density. 55 Cancri e was found to be one of the densest known planets.

The exoplanet orbits its star at a distance of only 0.015 AU. As a result, the temperatures on its surface are very high. For several years it was believed that due to its density and high temperatures 55 Cancri e was a planet consisting predominantly of carbon.

The data obtained in 2016 by the Hubble Telescope, however, have made this hypothesis fall. In fact, new research on its atmosphere has revealed large variations in temperature between the two hemispheres of the planet. It has been speculated that these differences can be explained through volcanic activity. On the hemisphere facing the star, temperatures reach 2500 Kelvin and it is believed that in this region there are many active volcanoes. On the shady hemisphere, temperatures are instead around 1600 Kelvin and it is believed that the surface here is made up of solidified lava.

Credit: ESA, Hubble. 

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