Related papers: Disentangling protoplanetary disk gas mass and car…

H$_2$CO is one of the most abundant organic molecules in protoplanetary disks and can serve as a precursor to more complex organic chemistry. We present an ALMA survey of H$_2$CO towards 15 disks covering a range of stellar spectral types,…

Young and directly imaged exoplanets offer critical tests of planet-formation models that are not matched by RV surveys of mature stars. These targets have been extremely elusive to date, with no exoplanets younger than 10--20 Myr and only…

In the past decade, the Atacama Large Millimeter/submillimeter Array (ALMA) has revealed a plethora of substructures in the disks surrounding young stars. These substructures have several proposed formation mechanisms, with one leading…

To study the high-transition dense-gas tracers and their relationships to the star formation of the inner $\sim$ 2 kpc circumnuclear region of NGC253, we present HCN $J=4-3$ and HCO$^+ J=4-3$ maps obtained with the James Clerk Maxwell…

Aims: To constrain the ionization fraction in protoplanetary disks, we present new high-sensitivity interferometric observations of N$_2$H$^+$ in three disks surrounding DM Tau, LkCa 15, and MWC 480. Methods: We used the IRAM PdBI array to…

Recent measurements of carbon isotope ratios in both protoplanetary disks and exoplanet atmospheres have suggested a possible transfer of significant carbon isotope fractionation from disks to planets. For a clearer understanding of the…

We present models for the HI 21 cm emission from circumstellar disks and use them to convert observed upper limits on the HI 21 cm flux to limits on the total disk gas mass. The upper limits we use come from earlier Australia Telescope…

Transitional disks around young stars are promising candidates to look for recently formed, embedded planets. Planet-disk interaction models predict that planets clear a gap in the gas while trapping dust at larger radii. Other physical…

We present the first detection of 13CCH in a protoplanetary disk (TW Hya). Using observations of C2H we measure CCH/13CCH = 65 +/- 20 in gas with a CO isotopic ratio of 12CO/13CO = 21 +/- 5 (Yoshida et al. 2022a). The TW Hya disk exhibits a…

Protoplanetary disks are composed primarily of gas (99% of the mass). Nevertheless, relatively few observational constraints exist for the gas in disks. In this review, I discuss several observational diagnostics in the UV, optical,…

The composition of planetary solids and gases is largely rooted in the processing of volatile elements in protoplanetary disks. To shed light on the key processes, we carry out a comparative analysis of the gas-phase carbon abundance in two…

The chemical properties of protoplanetary disks are especially sensitive to their ionization environment. Sources of molecular gas ionization include cosmic rays, stellar X-rays and short-lived radionuclides, each of which varies with…

The origin and evolution of gas in debris disks is still not well understood. Secondary gas production from cometary material or a primordial origin have been proposed. So far, observations have mostly concentrated on CO, with only few C…

Protoplanetary disc mass is one of the most fundamental properties of a planet-forming system, as it sets the total mass budget available for planet formation. However, obtaining disc mass measurements remain challenging, since it is not…

Determining the gas density and temperature structures of protoplanetary disks is a fundamental task to constrain planet formation theories. This is a challenging procedure and most determinations are based on model-dependent assumptions.…

CO is one of the most abundant molecules in protoplanetary disks, and optically thin emission from its isotopologues has been detected in many of them. However, several past works have argued that reproducing the relatively low emission of…

The total disk mass sets the formation potential for exoplanets. Carbon-monoxide (CO) has been used as a gas mass tracer in T Tauri disks, but was found to be less abundant than expected due to freeze-out and chemical conversion of CO on…

We present molecular line observations of 13CO and C18O J=3-2, CN N = 3 - 2, and CS J=7-6 lines in the protoplanetary disk around TW Hya at a high spatial resolution of ~9 au (angular resolution of 0.15''), using the Atacama Large…

The spatial distribution of the chemical reservoirs in protoplanetary disks is key to elucidate the composition of planets, especially habitable ones. However, the partitioning of the main elements among the refractory and volatile phases…

The nature of the gas in CO-rich debris discs remains poorly understood, as it could either be a remnant from the earlier Class II phase or of secondary origin, driven by the destruction of icy planetesimals. The aim of this paper was to…