Statistical Properties of super-Earth and Neptune-mass Planets from the Harps Survey.
Statistical Properties of super-Earth and Neptune-mass Planets from the Harps Survey.
I will present the results of an 8-year survey carried out
at La Silla Observatory with the HARPS
spectrograph to detect and characterize planets in the super-earth and
Neptune-mass regime. The size of our star sample and the precision achieved with HARPS have led to the
detection of a sufficiently large number of low-mass planets to study the statistical properties of their
orbital elements, the correlation of the host star metallicity with the planet masses, as well as
the occurrence rate of planetary systems around solar-type stars.
To describe the difficulties to detect Earth-twins , I will discuss the case of
Alpha Cen B .
Despite its rather low level of magnetic activity that star exhibits radial
velocity jitter
with short (weeks) and very long (several years) time-scale. Thanks to our very large velocity measurements of Alpha Cen B, these magnetic phenomena have
been characterized. Do we still have the possibility to detect Earth-twins by
Doppler spectroscopy ?
