Related papers: An Earth-sized exoplanet with a Mercury-like compo…
The bulk composition of an exoplanet is commonly inferred from its average density. For small planets, however, the average density is not unique within the range of compositions. Variations of a number of important planetary…
High-precision planetary densities are key to derive robust atmospheric properties for extrasolar planets. Measuring precise masses is the most challenging part, especially in multi-planetary systems. We measure the masses and densities of…
The Kepler mission has revealed that Earth-sized planets are common, and dozens have been discovered to orbit in or near their host star's habitable zone. A major focus in astronomy is to determine which of these exoplanets are likely to…
One of the unique aspects of Earth is that it has a fractionally large Moon, which is thought to have formed from a Moon-forming disk generated by a giant impact. The Moon stabilizes the Earth's spin axis at least by several degrees and…
The Earth-Moon system is unusual in several respects. The Moon is roughly 1/4 the radius of the Earth - a larger satellite-to-planet size ratio than all known satellites other than Pluto's Charon. The Moon has a tiny core, perhaps with only…
The Kepler planetary system consists of two exoplanets at similar separations (0.115 & 0.128 AU), which have dramatically different densities. The inner planet has a density consistent with an Earth-like composition, while the outer planet…
Atmospheric metal enrichment (i.e., elements heavier than helium, also called "metallicity") is a key diagnostic of the formation of giant planets. The giant planets of the solar system exhibit an inverse relationship between mass and both…
Modeling the interior of exoplanets is essential to go further than the conclusions provided by mean density measurements. In addition to the still limited precision on the planets' fundamental parameters, models are limited by the…
The size distribution of exoplanets is a bimodal division into two groups: Rocky planet (<2 Earth radii) and water-rich planet (>2 Earth radii) with or without gaseous envelope.
Mercury is the target of two space missions: MESSENGER (NASA) which orbit insertion is planned for March 2011, and ESA/JAXA BepiColombo, that should be launched in 2014. Their instruments will observe the surface of the planet with a high…
We know that giant planets played a crucial role in the making of our Solar System. The discovery of giant planets orbiting other stars is a formidable opportunity to learn more about these objects, what is their composition, how various…
Constraining the planetary composition is essential for exoplanetary characterization. In this paper, we use a statistical analysis to determine the characteristic maximum (threshold) radii for various compositions for exoplanets with…
Over the past two years, the search for low-mass extrasolar planets has led to the detection of seven so-called 'hot Neptunes' or 'super-Earths' around Sun-like stars. These planets have masses 5-20 times larger than the Earth and are…
Royal Society Discussion Meeting (2013) `Characterizing exoplanets'. Of the 900+ confirmed exoplanets discovered since 1995 for which we have constraints on their mass (i.e., not including Kepler candidates), 75% have masses larger than…
Metal-rich asteroids and iron meteorites are considered core remnants of differentiated planetesimals and or products of oxygen-depleted accretion. Investigating the origins of iron-rich planetesimals could provide key insights into planet…
To first order, the Earth as well as other rocky planets in the Solar System and rocky exoplanets orbiting other stars, are refractory pieces of the stellar nebula out of which they formed. To estimate the chemical composition of rocky…
Recent studies regarding the habitability, observability, and possible orbital evolution of the indirectly detected exoplanet Proxima b have mostly assumed a planet with $M \sim 1.3$ $M_\oplus$, a rocky composition, and an Earth-like…
A circumsolar dust ring has been recently discovered close to the orbit of Mercury. There are currently no hypotheses for the origin of this ring in the literature, so we explore four different origin scenarios here: the dust originated…
Mercury is notoriously difficult to form in solar system simulations, due to its small mass and iron-rich composition. Smooth particle hydrodynamics simulations of collisions have found that a Mercury-like body could be formed by one or…
Probing the interiors of the gas giant planets in our Solar System is not an easy task. It requires a set of accurate measurements combined with theoretical models that are used to infer the planetary composition and its depth dependence.…