Exoplanets with a radius smaller than 3 Earth radii span a wide range of characteristics. In fact, both low density sub-Neptunian and high-density Earth- and Mercury-like planets have been observed with such a radius. This diversity suggests that these planets, despite being formed in a similar way, followed different evolutionary patterns depending on the characteristics of their host stars, the
Super-Earths are exoplanets with radii between that of the Earth and that of Neptune (about 4 times the radius of the Earth), and with orbital periods smaller than 100 days. Although the Solar System does not host a similar planet, super-Earths are actually common in the Milky Way. This type of exoplanet is also interesting since they populate a gap
In our Galaxy, a large fraction of stars is part of binary systems. For instance, the study of Duquennoy & Mayor (1991) suggests a binary fraction of 57% for solar type stars. A slightly smaller binary fraction is expected for less massive stars. Among pre-Main Sequence stars, several binary systems are known to host a circumbinary disk. These disks are
The search of exoplanets relies mainly on two techniques: transits and radial velocity. With the former method exoplanets are revealed thanks to small and periodic dimming of the light of stars when their planets orbit across the stellar disk, producing a small eclipse. The method of radial velocity consists in revealing the oscillations of stars around the center of mass
The discovery of hot Jupiters (Jupiter-like exoplanets in close orbits) has changed our view of planet formation. It is still debated whether hot Jupiters form in the present-day orbits or they form at large distances from their star and then they migrate inward. (e.g. Maldonado et al. 2018). Planetary migration can be induced by several effects, mainly interaction between
The analysis of radial velocity is one of the two main methods used to detect exoplanets. This method consists in measuring the Doppler effect on stellar spectra deriving the velocity component along the line of sight (the radial velocity). If the star has a planet, they both orbit around the common center of mass, producing periodic oscillations of the osberved
di Mario Giuseppe Guarcello ( segui mguarce) A guardare il nostro Sistema Solare, sembrerebbe che il destino di un pianeta sia quello di girare attorno la sua stella in un’orbita stabile ed imperturbata. Ma se c’è una cosa che la ricerca sui pianeti extrasolari ci ha insegnato, è che non è affatto così. Soprattutto nelle sue prime
Exoplanets research has a wide appeal on the public and the scientific community. This mainly thanks to the results of successful missions such as CoRoT and Kepler, which allowed us to identify to date 3610 exoplanets, with more than 2000 candidates (link). However, the search for exoplanets is only part of this important branch of astrophysics, which faces several important questions still without answer:
