Related papers: X-ray Ionization of Heavy Elements Applied to Prot…
Young planets with masses approaching Jupiter's have tides strong enough to clear gaps around their orbits in the protostellar disk. Gas flow through the gaps regulates the planets' further growth and governs the disks' evolution. Magnetic…
We calculate the abundances of electrons and ions in the hot (> 500 K), dusty parts of protoplanetary disks, treating for the first time the effects of thermionic and ion emission from the dust grains. High-temperature ionization modeling…
Although stars accrete mass throughout the first few Myr of their lives, the physical mechanism that drives disk accretion in the T Tauri phase is uncertain, and diagnostics that probe the nature of disk accretion have been elusive,…
We present the results of a theoretical study investigating the effects of photoionization and heating by X-rays on discs around low-mass stars. In particular we address the question of whether or not X-rays can drive a disc wind. First, we…
Cosmic-ray and X-ray heating are derived from the electron energy loss calculations of Dalgarno, Yan and Liu for hydrogen-helium gas mixtures. These authors treated the heating from elastic scattering and collisional de-excitation of…
Non-solar composition of the donor star in ultra-compact X-ray binaries may have a pronounced effect on the fluorescent lines appearing in their spectra due to reprocessing of primary radiation by the accretion disk and the white dwarf…
T Tauri stars are known to be magnetically active stars subject to strong flares observed in X-rays. These flares are likely due to intense magnetic reconnection events during which a part of the stored magnetic energy is converted into…
The evolution of protoplanetary disks is believed to be driven largely by angular momentum transport resulting from magnetized disk winds and turbulent viscosity. The ionization of the disk that is essential for these processes has been…
Electron-impact ionization of an atom or ion in the presence of a neighboring atom is studied. The latter is first collisionally excited by the incident electron, whose energy is assumed to be high but nonrelativistic. Afterwards, the…
We explore the interactions between Argon and extreme ultraviolet (XUV) laser pulses across photon energies of 200 eV, 260 eV, and 315 eV, scrutinizing the influence of photon energy on Argon ion yields and unraveling the associated…
While it may seem counterintuitive that X-ray astronomy should give any insights into low-temperature planetary systems, planets orbit stars whose magnetized surfaces divert a small fraction of the stellar energy into high energy products:…
Context. Planets are thought to eventually form from the mostly gaseous (~99% of the mass) disks around young stars. The density structure and chemical composition of protoplanetary disks are affected by the incident radiation field at…
Using a thermal-chemical model for the generic T-Tauri disk of D'Alessio et al. (1999), we estimate the strength of the fine-structure emission lines of NeII and NeIII at 12.81 and 15.55 microns that arise from the warm atmosphere of the…
We examine heating and cooling in protostellar disks using 3-D radiation-MHD calculations of a patch of the Solar nebula at 1 AU, employing the shearing-box and flux-limited radiation diffusion approximations. The disk atmosphere is ionized…
The vast majority of young stars hosting planet-forming disks exist within clustered environments, like the Orion Nebula, implying that seemingly `extreme' UV environments (10^4 G_0 and above) are not so atypical in the context of planet…
The model is constructed of the propagation of gamma-ray burst radiation through a dense molecular cloud. The main processes of the interaction of the radiation with the interstellar gas are taken into account in the simulations: the…
Most of the mass in protoplanetary disks is in the form of gas. The study of the gas and its diagnostics is of fundamental importance in order to achieve a detailed description of the thermal and chemical structure of the disk. The…
The theory of resonant Auger decay of atoms in a high intensity coherent X-ray pulse is presented. The theory includes the coupling between the ground state and the resonance due to an intense X-ray pulse, taking into account the decay of…
The deuterium enrichment of organics in the interstellar medium, protoplanetary disks and meteorites has been proposed to be the result of ionizing radiation. The goal of this study is to quantify the effects of soft X-rays (0.1 - 2 keV), a…
We present MOCASSIN 2D photoionisation and dust radiative transfer models of a prototypical T Tauri disk irradiated by X-rays from the young pre-main sequence star. The calculations demonstrate a layer of hot gas reaching temperatures of…