Related papers: Cosmic Hydrogen and Ice Loss Lines
The snow line in a protoplanetary disk demarcates regions with H$_2$O ice from regions with H$_2$O vapor. Where a planet forms relative to this location determines how much water and other volatiles it forms with. Giant planet formation may…
Recent observations have successfully detected UV or infrared flux from galaxies at the epoch of reionization. However, the origin of their radiative properties has not been fully understood yet. Combining cosmological hydrodynamic…
Strong atmospheric escape has been detected in several close-in exoplanets. As these planets consist mostly of hydrogen, observations in hydrogen lines, such as Ly-alpha and H-alpha, are powerful diagnostics of escape. Here, we simulate the…
We present chemical evolution models of the Galactic disk with different Z-dependent yields. We find that a moderate mass loss rate for massive stars of solar metallicity produces an excellent fit to the observed C/H and C/O gradients of…
CO is the most widely used gas tracer of protoplanetary disks. Its abundance is usually assumed to be an interstellar ratio throughout the warm molecular layer of the disk. But recent observations of low CO gas abundance in many…
Hydrogen emission lines can provide extensive information about star-forming galaxies in both the local and high-redshift Universe. We present a detailed Lyman continuum (LyC), Lyman-alpha (Ly{\alpha}), and Balmer line (H{\alpha} and…
Detailed models for the density and temperature profiles of gas and dust in protoplanetary disks are constructed by taking into account X-ray and ultraviolet (UV) irradiation from a central T Tauri star, as well as dust size growth and…
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 spatial distribution and lifetime of molecular gas in the inner regions of young circumstellar disks are key to understanding the formation of planetary systems. Gas-rich disks are observed to disperse in the first ~10 Myr, and recent…
Gas-giant exoplanets are test cases for theories of planet formation as their atmospheres are proposed to carry signatures of their formation within the protoplanetary disk. The metallicity and C/O are key diagnostics, allowing to…
The radius valley (or gap) in the observed distribution of exoplanet radii, which separates smaller super-Earths from larger sub-Neptunes, is a key feature that theoretical models must explain. Conventionally, it is interpreted as the…
Observations have revealed that the elemental abundances of carbon and oxygen in the warm molecular layers of some protoplanetary disks are depleted compared to those is the interstellar medium by a factor of ~10-100. Meanwhile, little is…
We re-examine the constraints provided by Herschel Space Observatory data regarding cold water emission from protoplanetary disks. Previous disk models that were used to interpret observed water emission concluded that oxygen (O/H) is…
Context. Ice lines are suggested to play a significant role in grain growth and planetesimal formation in protoplanetary disks. Evaporation fronts directly influence the gas and ice abundances of volatile species in the disk and therefore…
HI 21cm-line self-absorption (HISA) reveals the shape and distribution of cold atomic clouds in the Galactic disk. Many of these clouds lack corresponding CO emission, despite being colder than purely atomic gas in equilibrium models. HISA…
Studies of planetary atmospheric composition, variability, and evolution require appropriate theoretical and numerical tools to estimate key atmospheric parameters, among which the mass-loss rate is often the most important. In evolutionary…
The increased sensitivity of millimeter-wave facilities now makes possible the detection of low amounts of gas in debris disks. Some of the gas-rich debris disks harbor peculiar properties, with possible pristine gas and secondary generated…
We study the evolution of the cold gas content of galaxies by splitting the interstellar medium into its atomic and molecular hydrogen components, using the galaxy formation model GALFORM in the LCDM framework. We calculate the…
Planet formation models suggest that the small exoplanets that migrate from beyond the snowline of the protoplanetary disk likely contain water-ice-rich cores ($\sim 50\%$ by mass), also known as the water worlds. While the observed radius…
In the present chapter we present the results of evolutionary studies of exoplanetary atmospheres. We mostly focus on the sub- to super-Earth domain, although these methods are applicable to all types of exoplanets. We consider both thermal…