Related papers: CO destruction in protoplanetary disk midplanes: i…
CO is an important component of a protoplanetary disc as it is one of the most abundant gas phase species. Furthermore, observations of the CO transitions can be used as a diagnostic of the gas, tracing conditions in both the inner and…
Aims: To calculate chemistry and gas temperature of evolving protoplanetary disks with decreasing mass or dust settling, and to explore the sensitivity of gas-phase tracers. Methods: The density and dust temperature profiles for a range of…
The disk midplane temperature is potentially affected by the dust traps/rings. The dust depletion beyond the water snowline will cast a shadow. In this study, we adopt a detailed gas-grain chemical reaction network, and investigate the…
We carried out a 12CO(3-2) survey of 52 southern stars with a wide range of IR excesses (LIR/L*) using the single dish telescopes APEX and ASTE. The main aims were (1) to characterize the evolution of molecular gas in circumstellar disks…
In regions where stars form, variations in density and temperature can cause gas to freeze-out onto dust grains forming ice mantles, which influences the chemical composition of a cloud. The aim of this paper is to understand in detail the…
Protoplanetary discs around Very Low Mass Stars (VLMS) show hydrocarbon-rich MIR spectra indicative of C/O>1 in their inner discs, in contrast to discs around higher-mass hosts which mostly show O-bearing species. One scenario proposed to…
Potential signatures of proto-planets embedded in their natal protoplanetary disk are radial gaps or cavities in the continuum emission in the IR-mm wavelength range. ALMA observations are now probing spatially resolved rotational line…
Observations of CO isotopologue emission from protoplanetary disks at millimeter wavelengths are a powerful tool for probing the CO snowline, an important marker for disk chemistry, and also for estimating total disk gas mass, a key…
The total gas mass of a protoplanetary disk is a fundamental, but poorly determined, quantity. A new technique \citep{bergin+13} has been demonstrated to assess directly the bulk molecular gas reservoir of molecular hydrogen using the HD…
H$_2$CO ice on dust grains is an important precursor of complex organic molecules (COMs). H$_2$CO gas can be readily observed in protoplanetary disks and may be used to trace COM chemistry. However, its utility as a COM probe is currently…
We present ISO-SWS observations of H2 pure-rotational line emission from the disks around low and intermediate mass pre-main-sequence stars as well as from young stars thought to be surrounded by debris disks. We detect `warm' (T ~ 100-200…
(Abridged) Aims & Methods. A two-dimensional, semi-analytical model is presented that follows, for the first time, the chemical evolution from a collapsing molecular cloud (a pre-stellar core) to a protostar and circumstellar disk. The…
The evolution of the gas mass of planet-forming disks around young stars is crucial for our understanding of planet formation, yet it has proven hard to constrain observationally, due both to the difficulties of measuring gas masses and the…
This paper introduces a new disk code, called ProDiMo, to calculate the thermo-chemical structure of protoplanetary disks and to interpret gas emission lines from UV to sub-mm. We combine frequency-dependent 2D dust continuum radiative…
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…
The disks that surround young stars are mostly composed of molecular gas, which is harder to detect and interpret than the accompanying dust. Disk mass measurements have therefore relied on large and uncertain extrapolations from the dust…
Based on the interstellar CO/H2 ratio, carbon monoxide-based censuses of protoplanetary disks in Lupus, sigma Orionis, and Chamaeleon I found no disks more massive than the minimum-mass solar nebula, which is inconsistent with the existence…
The $\rm H_2$ mass of molecular clouds has traditionally been traced by the CO(J=1-0) rotational transition line. This said, CO is relatively easily photodissociated, and can also be destroyed by cosmic rays, thus rendering some fraction of…
We have investigated molecular distributions in protoplanetary disks, adopting a disk model with a temperature gradient in the vertical direction. The model produces sufficiently high abundances of gaseous CO and HCO+ to account for line…
CO is widely used as a tracer of molecular gas. However, there is now mounting evidence that gas phase carbon is depleted in the disk around TW Hya. Previous efforts to quantify this depletion have been hampered by uncertainties regarding…