Related papers: The Origin of the Exoplanets
The Solar System includes two planets --- Mercury and Mars --- significantly less massive than Earth, and all evidence indicates that planets of similar size orbit many stars. In fact, one of the first exoplanets to be discovered is a…
Stars and planets both form by accreting material from a surrounding disk. Because they grow from the same material, theory predicts that there should be a relationship between their compositions. In this study, we search for a…
Exoplanet surveys have confirmed one of humanity's (and all teenagers') worst fears: we are weird. If our Solar System were observed with present-day Earth technology -- to put our system and exoplanets on the same footing -- Jupiter is the…
Exoplanets observed by the {\it Kepler} telescope exhibit a bi-modal, radius distribution, which is known as the radius gap. We explore an origin of the radius gap, focusing on multi-planet systems. Our simple theoretical argument predicts…
In order to gain a better understanding of planet formation and evolution, it is important to examine the statistics of exoplanets in the Galactic context. By combining information on stellar elemental abundances and kinematics, we…
The recent detection of planets around very low mass stars raises the question of the formation, composition and potential habitability of these objects. We use planetary system formation models to infer the properties, in particular their…
We suggest that planets, brown dwarfs, and even low mass stars can be formed by fragmentation of protoplanetary disks around very massive stars M>~100 solar masses. We discuss how fragmentation conditions make the formation of very massive…
The ubiquity of planets poses an interesting question: when first planets are formed in galaxies. We investigate this problem by adopting a theoretical model developed for understanding the statistical properties of exoplanets. Our model is…
Recent exoplanet surveys revealed that for solar-type stars, close-in Super-Earths are ubiquitous and many of them are in multi-planet systems. These systems are more compact than the Solar System's terrestrial planets. However, there have…
The timing of formation for the first planetesimals determines the mode of planetary accretion and their geophysical and compositional evolution. Astronomical observations of circumstellar discs and Solar System geochronology provide…
Kepler planets (including super-Earths and sub-Neptunes, from 1 to 4 Earth radii) are likely formed before the gaseous proto-planetary disks have dissipated, as are the Jovian planets. If the metal content in these disks resembles that in…
Approximately half of Sun-like stars harbor exoplanets packed within a radius of ~0.3 AU, but the formation of these planets and why they form in only half of known systems are still not well understood. We employ a one-dimensional steady…
We explore the relations between physical and orbital properties of planets and properties of their host stars to identify the main observable signatures of the formation and evolution processes of planetary systems. We use a large sample…
In this article, I examine several observational trends regarding protoplanetary disks, debris disks and exoplanets in binary systems in an attempt to constrain the physical mechanisms of planet formation in such a context. Binaries wider…
The nearly circular (mean eccentricity <e>~0.06) and coplanar (mean mutual inclination <i>~3 deg) orbits of the Solar System planets motivated Kant and Laplace to put forth the hypothesis that planets are formed in disks, which has…
One important property in studying the exoplanet population is the host star metallicity ([M/H]). In this study, we derived stellar metallicities and oxygen abundances for 48 M dwarf stars using the near-infrared high-resolution spectra…
Dozens of planets and brown dwarfs are known to orbit one component of tight stellar binaries ($a_{\rm bin} \lesssim 20$ au), despite circumstellar discs in such systems being truncated to radii of only $\sim (0.2-5)$ au. This presents a…
Most observed extrasolar planets have masses similar to, but orbits very different from, the gas giants of our solar system. Many are much closer to their parent stars than would have been expected and their orbits are often rather…
Extensive spectroscopic studies of stars with and without planets have concluded that stars hosting planets are significantly more metal-rich than those without planets. More subtle trends of different chemical elements begin to appear as…
Free-floating planets are a new class of planets recently discovered. These planets don't orbit within stellar systems, instead living a nomadic life within the galaxy. How such objects formed remains elusive. Numerous works have explored…