Related papers: The Hunt for Planet Nine: Atmosphere, Spectra, Evo…
Non-rocky sub-jovian exoplanets in high irradiation environments are rare. LTT 9979b, also known as TESS Object of Interest (TOI) 193.01, is one of the few such planets discovered to date, and the first example of an ultra-hot Neptune. The…
Emission from the molecular ion H$_3^+$ is a powerful diagnostic of the upper atmosphere of Jupiter, Saturn, and Uranus, but it remains undetected at Neptune. In search of this emission, we present near-infrared spectral observations of…
There are no planets intermediate in size between Earth and Neptune in our Solar System, yet these objects are found around a substantial fraction of other stars. Population statistics show that close-in planets in this size range bifurcate…
We use Keck/NIRSPEC to survey a sample of of young ($<$1 Gyr), short period mini Neptunes orbiting nearby K dwargs to measure their mass loss via the metastable helium line. We detect helium absorption from all four of the targets in our…
We generalize the problem of the semi-gray model to cases in which a non-negligible fraction of the stellar radiation falls on the long-wavelength range, and/or that the planetary long-wavelength emission penetrates into the transparent…
The TOI-421 planetary system contains two sub-Neptune-type planets and is a prime target to study the formation and evolution of planets and their atmospheres. The inner planet is especially interesting as the existence of a…
We present a search for helium in the upper atmospheres of three sub-Neptune size planets to investigate the origins of these ubiquitous objects. The detection of helium for a low density planet would be strong evidence for the presence of…
Motivated by recent detection of transiting high-density super-Earths, we explore the detectability of hot rocky super-Earths orbiting very close to their host stars. In the environment hot enough for their rocky surfaces to be molten, they…
Sub-Neptune planets are often modeled with a dense rocky or metal-rich interior beneath a thick hydrogen/helium (H/He) atmosphere; though their bulk densities could also be explained by a water-rich interior with a thin H/He atmosphere.…
Over the last decade, precise exoplanet transmission spectroscopy has revealed the atmospheres of dozens of exoplanets, driven largely by observatories like the Hubble Space Telescope. One major discovery has been the ubiquity of…
Photoevaporative models predict that the lower edge of the Neptune desert is sculpted by atmospheric mass loss. However, the stellar high energy fluxes that power hydrodynamic escape and set predicted mass loss rates can be uncertain by…
The atmospheric pressure-temperature profiles for transiting giant planets cross a range of chemical transitions. Here we show that the particular shape of these irradiated profiles for warm giant planets below 1300 K lead to striking…
We present the discovery of the Kepler-19 planetary system, which we first identified from a 9.3-day periodic transit signal in the Kepler photometry. From high-resolution spectroscopy of the star, we find a stellar effective temperature…
Planets residing within the hot-Neptune Desert are rare, and studying their atmospheres can provide valuable insights into their formation and evolutionary processes. We present the atmospheric characterization of the first known ultra-hot…
Neptune-size exoplanets are less studied as characterizing their atmospheres presents challenges due to their relatively small radius and atmospheric scale height. As the most common outcome of planet formation, these planets are crucial…
Constraining the composition of super-Earth-to-sub-Neptune-size planets is a priority to understand the processes of planetary formation and evolution. pi Men c represents a unique target for the atmospheric and compositional…
Spectral observations of Neptune made in 2019 with the MUSE instrument at the Very Large Telescope in Chile have been analysed to determine the spatial variation of aerosol scattering properties and methane abundance in Neptune's…
The nearby star GJ 1214 hosts a planet intermediate in radius and mass between Earth and Neptune, resulting in some uncertainty as to its nature. We have observed this planet, GJ 1214b, during transit with the high-resolution, near-infrared…
We use an extensive suite of numerical simulations to constrain the mass and orbit of Planet Nine, the recently proposed perturber in a distant eccentric orbit in the outer solar system. We compare our simulations to the observed population…
The recently discovered low-density "super-Earths" Kepler-11b, Kepler-11f, Kepler-11d, Kepler-11e, and planets such as GJ 1214b represent most likely planets which are surrounded by dense H/He envelopes or contain deep H2O oceans also…