Janssen (exoplanet)

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Exoplanet
Janssen

The earth in comparison with Janssen

The earth in comparison with Janssen
Constellation cancer
Position
equinox : J2000.0
Right ascension 08h 52m 35.81093s
declination + 28 ° 19 ′ 50.9511 ″
Orbit data
Central star Copernicus A
Major semi-axis 0.015439 ± 0.000015 AU
eccentricity 0.028   +0.022−0.019
Period of circulation 0.736548   +0.0000016−0.0000012
Further data
radius 1.91 ± 0.08 R ⊕
Dimensions 8.08 ± 0.31 M ⊕
distance 12.5 pc
method Radial velocity method
Orbit inclination 90.36   +3.96−4.66 deg
history
discovery Barbara Mc Arthur et al.
Date of discovery 2004
Catalog names
55 Cancri e, HD 75732 e

Janssen ( 55 Cancri e ) is an exoplanet orbiting component A of the binary star system Copernicus . It is the innermost planet of its planetary system . Its rather low mass for an exoplanet and its extreme proximity to a star fuel speculation that it could be a massive terrestrial planet , a so-called super - earth . At the time of discovery, it was the lowest-mass known planet around a sun-like star.

discovery

Janssen was discovered using the radial velocity method. At the time this planet was discovered, three other planets were already known in the Copernicus A system. The planet was discovered by Barbara McArthur and co-workers through observations with the Hobby Eberly Telescope at the McDonald Observatory in Texas and published in 2004. Later observations confirm the discovery.

Circulation and mass

According to the Spitzer Space Telescope in 2011, the planet is extremely close to its star at a distance of 0.015 astronomical units , at least 26 times closer than Mercury . If the earth were in the same position, the soil would be heated to 1760 ° C. The planet completes an orbit every 18 hours and has 7.8 times the mass of the earth .

Physical Properties

With R p of about 2 earth radii, Janssen is about twice the size of the earth. With this size and mass, it falls into the super-earth category . The Spitzer data suggest that about a fifth of the planet's mass must consist of light elements and compounds, including water. Due to the intense heat and high pressure, to these materials probably know, the researchers suggest that the compounds in a supercritical fluid state exist. The mass and radius of the planet can also be explained by a carbon-rich interior, which consists of iron , carbon , silicon and / or silicates . The carbon could be in the form of diamond due to the temperature and pressure . This means that Janssen's composition would be completely different from that of the earth, which has practically no carbon inside.

The planet has unusually large temperature differences between day and night. Temperatures of up to 2400 degrees Celsius can be found on the day side of the planet, while a maximum of 1100 degrees is reached on the night side.

Origin of name

Like all exoplanets, Janssen was originally named with the star's official name and a lowercase letter, according to the order in which it was discovered. After a public IAU competition , it was officially named on December 15, 2015 after the Dutch optician Zacharias Janssen .

swell

Web links

Commons : 55 Cancri e  - collection of images, videos and audio files

Individual evidence

  1. ↑ Simbad
  2. ↑ a b c d e f Exoplanet.eu
  3. ↑ a b Nasa Exoplanet Archive
  4. ↑ N. Madhusudhan, KKM Lee, O. Mousis: A Possible Carbon-rich Interior in Super-Earth 55 Cancri e. The Astrophysical Journal , 759 (2012), L40. doi: 10.1088 / 2041-8205 / 759/2 / L40 , arxiv : 1210.2720
  5. ↑ Brice-Olivier Demory, Michael Gillon, Julien de Wit, et al .: A map of the large day-night temperature gradient of a super-Earth exoplanet. Nature (2016), doi: 10.1038 / nature17169
  6. ↑ International Astronomical Union: NameExoWorlds - The Approved Names. Retrieved January 3, 2016 .