Browsing by Author "Munoz-Romero, Carlos E."

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    Cold Deuterium Fractionation in the Nearest Planet-forming Disk
    (2023) Munoz-Romero, Carlos E.; Oberg, Karin I.; Law, Charles J.; Teague, Richard; Aikawa, Yuri; Bergner, Jennifer B.; Wilner, David J.; Huang, Jane; Guzman, Viviana V.; Cleeves, L. Ilsedore
    Deuterium fractionation provides a window into the thermal history of volatiles in the solar system and protoplanetary disks. While evidence of active molecular deuteration has been observed toward a handful of disks, it remains unclear whether this chemistry affects the composition of forming planetesimals due to limited observational constraints on the radial and vertical distribution of deuterated molecules. To shed light on this question, we introduce new Atacama Large Millimeter/submillimeter Array observations of DCO+ and DCN J = 2-1 at an angular resolution of 0.'' 5 (30 au) and combine them with archival data of higher energy transitions toward the protoplanetary disk around TW Hya. We carry out a radial excitation analysis assuming both LTE and non-LTE to localize the physical conditions traced by DCO+ and DCN emission in the disk, thus assessing deuterium fractionation efficiencies and pathways at different disk locations. We find similar disk-averaged column densities of 1.9 x 10(12) and 9.8 x 10(11) cm(-2) for DCO+ and DCN, with typical kinetic temperatures for both molecules of 20-30 K, indicating a common origin near the comet- and planet-forming midplane. The observed DCO+/DCN abundance ratio, combined with recent modeling results, provide tentative evidence of a gas-phase C/O enhancement within <40 au. Observations of DCO+ and DCN in other disks, as well as HCN and HCO+, will be necessary to place the trends exhibited by TW Hya in context, and fully constrain the main deuteration mechanisms in disks.
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    JWST-MIRI Spectroscopy of Warm Molecular Emission and Variability in the AS 209 Disk
    (2024) Munoz-Romero, Carlos E.; Oberg, Karin I.; Banzatti, Andrea; Pontoppidan, Klaus M.; Andrews, Sean M.; Wilner, David J.; Bergin, Edwin A.; Czekala, Ian; Law, Charles J.; Salyk, Colette; Teague, Richard; Qi, Chunhua; Bergner, Jennifer B.; Huang, Jane; Walsh, Catherine; Guzman, Viviana V.; Cleeves, L. Ilsedore; Aikawa, Yuri; Bae, Jaehan; Booth, Alice S.; Cataldi, Gianni; Ilee, John D.; Le Gal, Romane; Long, Feng; Loomis, Ryan A.; Menard, Francois; Liu, Yao
    We present MIRI Medium-resolution Spectrograph observations of the large, multi-gapped protoplanetary disk around the T Tauri star AS 209. The observations reveal hundreds of water vapor lines from 4.9-25.5 mu m toward the inner similar to 1 au in the disk, including the first detection of rovibrational water emission in this disk. The spectrum is dominated by hot (similar to 800 K) water vapor and OH gas, with only marginal detections of CO2, HCN, and a possible colder water vapor component. Using slab models with a detailed treatment of opacities and line overlap, we retrieve the column density, emitting area, and excitation temperature of water vapor and OH, and provide upper limits for the observable mass of other molecules. Compared to MIRI spectra of other T Tauri disks, the inner disk of AS 209 does not appear to be atypically depleted in CO2 nor HCN. Based on Spitzer Infrared Spectrograph observations, we further find evidence for molecular emission variability over a 10 yr baseline. Water, OH, and CO2 line luminosities have decreased by factors of 2-4 in the new MIRI epoch, yet there are minimal continuum emission variations. The origin of this variability is yet to be understood.