Related papers: An Oxidation Gradient Straddling the Small Planet …
Close-in planets smaller than Neptune form two distinct populations composed of rocky super-Earths and sub-Neptunes that may host primordial H/He envelopes. The origin of the radius valley separating these two planet populations remains an…
The recent discovery and initial characterization of sub-Neptune-sized exoplanets that receive stellar irradiance of approximately Earth's raised the prospect of finding habitable planets in the coming decade, because some of these…
The nature of sub-Neptunes remains unknown due to degeneracies in interior structure solutions. However, a statistical set of small planets with measured masses and radii can be used to test the planet formation theory prediction of large…
The magma ocean period was a critical phase determining how Earth atmosphere developed into habitability. However there are major uncertainties in the role of key processes such as outgassing from the planetary interior and escape of…
Rocky planets may acquire a primordial atmosphere by outgassing of volatiles from their magma ocean. The distribution of O between H$_2$O, CO and CO$_2$ in chemical equilibrium subsequently changes significantly with decreasing temperature.…
Here we investigate how small amounts of hydrogen (much smaller than the mass of the exoplanet) above a magma ocean on a rocky exoplanet may modify the atmospheric chemistry and atmospheric escape.We use a chemical model of a magma ocean…
The geology of Earth and super-Earth sized planets will, in many cases, only be observable via their atmospheres. Here, we investigate secondary volcanic atmospheres as a key base case of how atmospheres may reflect planetary geochemistry.…
The observed masses and radii of sub-Neptunes are typically explained by the gas dwarf and the water world scenarios. While their evolutionary history on a population level has been proposed as a method to distinguish between these…
The low mean densities of sub-Neptunes imply that they formed within a few million years and accreted primordial envelopes. Because these planets receive a total X-ray and extreme ultra-violet flux that is comparable to the gravitational…
The evolution of exoplanetary atmospheres is strongly influenced by atmospheric escape, particularly for close-in planets. Fractionation during atmospheric loss can preferentially remove lighter elements such as hydrogen, while retaining…
Absorption of high-energy radiation in planetary thermospheres is believed to lead to the formation of planetary winds. The resulting mass-loss rates can affect the evolution, particularly of small gas planets. We present 1D, spherically…
The recent JWST detections of carbon-bearing molecules in a habitable-zone sub-Neptune have opened a new era in the study of low-mass exoplanets. The sub-Neptune regime spans a wide diversity of planetary interiors and atmospheres not…
Planet atmospheric escape induced by high-energy stellar irradiation is a key phenomenon shaping the structure and evolution of planetary atmospheres. Therefore, the present-day properties of a planetary atmosphere are intimately connected…
Here we discuss the current state of knowledge on how atmospheric escape processes can fractionate noble gas isotopes and moderately volatile rock-forming elements that populate primordial atmospheres, magma ocean related environments, and…
Warm Neptune- and sub-Neptune-sized exoplanets in orbits smaller than Mercury's are thought to have experienced extensive atmospheric evolution. Here we propose that a potential outcome of this atmospheric evolution is the formation of…
Low-gravity waterworlds ($M\lesssim 0.1 M_{\oplus}$) are of interest for their potential habitability. The weakly bound atmospheres of such worlds have proportionally larger radiative surfaces and are more susceptible to escape. We conduct…
Low-mass low-density planets discovered by Kepler in the super-Earth mass regime typically have large radii for their inferred masses, implying the presence of H$_2$-He atmospheres. These planets are vulnerable to atmospheric mass loss due…
Sub-Neptunes (planets with radii between 2 and 4 R$_{\oplus}$) are abundant around M-dwarf stars, yet the atmospheric dynamics of these planets is relatively unexplored. In this paper, we aim to provide a basic underpinning of the dry…
Understanding the planetary envelope composition of sub-Neptune-type exoplanets is challenging due to the inherent degeneracy in their interior composition scenarios. Particularly, the planetary envelope's H2O/H2 ratio, which can also be…
Super-Earths and sub-Neptunes are the most common exoplanets, with a "radius valley" suggesting that super-Earths may form by shedding sub-Neptunes' gaseous envelopes. Exoplanets that lie closer to the super-Earth side of the valley are…