55 Cancri e

55 Cancri e is an extrasolar planet orbiting the component A of the binary system 55 Cancri. He is the innermost planet, its planetary system. Its a rather small mass exoplanets and the extreme proximity to a star nourish speculation that it could be a massive terrestrial planet, a so-called super-Earth. At the time of discovery it was the least massive known planet around a Sun-like star.

Discovery

As the majority of exoplanets was also discovered 55 Cancri e using the radial velocity method. At the time of the discovery of this planet three other planets in the 55 Cancri - A system, were already known. The planet was discovered by Barbara McArthur and staff through observations with the Hobby - Eberly Telescope at McDonald Observatory in Texas and published in 2004. Later observations confirm the discovery.

Circulation and mass

The planet is - after observing the Spitzer Space Telescope of 2011 - with a distance of 0.015 astronomical units extremely close to its star, at least 26 times closer than Mercury. Would be the earth at the same position of the base would be heated to 1760 ° C. The planet completes one revolution every 18 hours and has the 7.8 times Earth's mass.

Physical Properties

55 Cancri e is with Rp = 2.173 ± 0.09 Earth radii slightly more than twice as large as the Earth. With this size and mass, it falls in the category of super-Earths. The Spitzer data suggest that about a fifth of the planet mass of light elements and compounds - there must be - including water. Because of the intense heat and high pressure, the materials are likely to discover this, the researchers assume that the compounds exist in a supercritical fluid state. But mass and radius of the planet can also be explained by a carbon-rich interior that is made of iron, carbon, silicon and / or silicates. The carbon may be present due to the temperature and pressure in the form of diamond. Thus, the composition of 55 Cancri e would be completely different than that of the Earth, which has virtually no carbon in its interior.

Swell

  • B. McArthur et al.: Detection of a Neptune -mass planet in the ρ1 Cnc system using the Hobby - Eberly Telescope. The Astrophysical Journal, 614 (2004), pp. L81 - L84. doi: 10.1086/425561, arXiv: astro-ph/0408585
  • Debra A. Fischer et al.: Five Planets Orbiting 55 Cancri. The Astrophysical Journal, 675 (2008), pp. 790-801. doi: 10.1086/525512, arXiv: 0712.3917
  • Michaël Gillon et al.: Improved precision on the radius of the nearby super- Earth 55 Cnc e Astronomy & Astrophysics, 539 (2012), A28. doi: 10.1051/0004-6361/201118309, arXiv: 1110.4783
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