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Studying extrasolar planets with CoRoT

given by Eike Guenther (Thüringer Landessternwarte Tautenburg, DE)

Nov 29, 2012 from 02:00 PM to 05:00 PM

Where Seminars' room, floor -1, via Ranzani 1

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Studies of transiting extra-solar planets are of key importance for
understanding the nature of planets outside our solar system, because
their densities can be determined which tells us of what the
planets are made of.  In our solar-system we have basically two species of
planets: gas or ice giants which have masses larger than 15 MEarth and
densities  between 0.7 to 1.6 gcm-3, and rocky planets which have
densities from 3.7 to 5.5 gcm-3.  It is thus natural to
expect that planets outside the solar system should have the same
properties: Planets with more than 15 MEarth should have a low density,
and planets with the mass of the Earth should have a high density. The
CoRoT satellite has now discovered more than 26 transiting extrasolar
planets including the first rocky one, which allows to draw first
conclusions.
The first surprising results is  that planets of the same mass can have
different densities but there are still some trends:
Planets with more than 1000 MEarth have densities
larger than 6 gcm-3, and are preferentially found in stars
that are more massive than the Sun. All known planets in the
mass-range between 15 and 600 MEarth have densities of less
than 3 gcm^-3.  When going further down in the mass of the planets, the
density of planets increases but there is no sudden transition from
gaseous to rocky planets.

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