Browsing by Author "Huang, Jane"

Now showing 1 - 20 of 39
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    A Dust-trapping Ring in the Planet-hosting Disk of Elias 2-24
    (2024) Carvalho, Adolfo S.; Perez, Laura M.; Sierra, Anibal; Mellado, Maria Jesus; Hillenbrand, Lynne A.; Andrews, Sean; Benisty, Myriam; Birnstiel, Tilman; Carpenter, John M.; Guzman, Viviana V.; Huang, Jane; Isella, Andrea; Kurtovic, Nicolas; Ricci, Luca; Wilner, David J.
    Rings and gaps are among the most widely observed forms of substructure in protoplanetary disks. A gap-ring pair may be formed when a planet carves a gap in the disk, which produces a local pressure maximum following the gap that traps inwardly drifting dust grains and appears as a bright ring owing to the enhanced dust density. A dust-trapping ring would provide a promising environment for solid growth and possibly planetesimal production via the streaming instability. We present evidence of dust trapping in the bright ring of the planet-hosting disk Elias 2-24, from the analysis of 1.3 and 3 mm Atacama Large Millimeter/submillimeter Array observations at high spatial resolution (0.'' 029, 4.0 au). We leverage the high spatial resolution to demonstrate that larger grains are more efficiently trapped and place constraints on the local turbulence (8 x 10(-4) < alpha( turb) < 0.03) and the gas-to-dust ratio (Sigma (g) /Sigma (d) < 30) in the ring. Using a scattering-included marginal probability analysis, we measure a total dust disk mass of M-dust=13.8(-0.5)+0.7x10(-4)M(circle dot) . We also show that at the orbital radius of the proposed perturber the gap is cleared of material down to a flux contrast of 10(-3) of the peak flux in the disk.
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    ALMA Observations of the Epoch of Planet Formation
    (2018) Andrews, Sean M.; Huang, Jane; Pérez, Laura M.; Isella, Andrea; Dullemond, Cornelis P.; Kurtovic, Nicolás T.; Guzmán Veloso, Viviana Gabriela; Carpenter, John M.; Wilner, David J.; Zhang, Shangjia; Birnstiel, Tilman; Bai, Xue-Ning; Benisty, Myriam; Hughes, A. Meredith; Öberg, Karin I.; Ricci, Luca
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    An ALMA Survey of H2CO in Protoplanetary Disks
    (IOP PUBLISHING LTD, 2020) Pegues, Jamila; Oberg, Karin I.; Bergner, Jennifer B.; Loomis, Ryan A.; Qi, Chunhua; Le Gal, Romane; Cleeves, L. Ilsedore; Guzman, Viviana V.; Huang, Jane; Jorgensen, Jes K.; Andrews, Sean M.; Blake, Geoffrey A.; Carpenter, John M.; Schwarz, Kamber R.; Williams, Jonathan P.; Wilner, David J.
    H2CO 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 Atacama Large Millimeter/submillimeter Array survey of H2CO toward 15 disks covering a range of stellar spectral types, stellar ages, and dust continuum morphologies. H2CO is detected toward 13 disks and tentatively detected toward a fourteenth. We find both centrally peaked and centrally depressed emission morphologies, and half of the disks show ring-like structures at or beyond expected CO snowline locations. Together these morphologies suggest that H2CO in disks is commonly produced through both gas-phase and CO-ice-regulated grain-surface chemistry. We extract disk-averaged and azimuthally-averaged H2CO excitation temperatures and column densities for four disks with multiple H2CO line detections. The temperatures are between 20-50 K, with the exception of colder temperatures in the DM Tau disk. These temperatures suggest that H2CO emission in disks generally emerges from the warm molecular layer, with some contributions from the colder midplane. Applying the same H2CO excitation temperatures to all disks in the survey, we find that H2CO column densities span almost three orders of magnitude (similar to 5 x 10(11) -5 x 10(14) cm(-2)). The column densities appear uncorrelated with disk size and stellar age, but Herbig Ae disks may have less H2CO compared to T Tauri disks, possibly because of less CO freeze-out. More H2CO observations toward Herbig Ae disks are needed to confirm this tentative trend, and to better constrain under which disk conditions H2CO and other oxygen-bearing organics efficiently form during planet formation.
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    An Atacama Large Millimeter/submillimeter Array Survey of Chemistry in Disks around M4-M5 Stars
    (2021) Pegues, Jamila; Oberg, Karin I.; Bergner, Jennifer B.; Huang, Jane; Pascucci, Ilaria; Teague, Richard; Andrews, Sean M.; Bergin, Edwin A.; Cleeves, L. Ilsedore; Guzman, Viviana V.; Long, Feng; Qi, Chunhua; Wilner, David J.
    M-stars are the most common hosts of planetary systems in the Galaxy. Protoplanetary disks around M-stars thus offer a prime opportunity to study the chemistry of planet-forming environments. We present an Atacama Large Millimeter/submillimeter Array survey of molecular line emission toward a sample of five protoplanetary disks around M4-M5 stars (FP Tau, J0432+1827, J1100-7619, J1545-3417, and Sz 69). These observations can resolve chemical structures down to tens of astronomical units. Molecular lines of (CO)-C-12, (CO)-C-13, (CO)-O-18, C2H, and HCN are detected toward all five disks. Lines of H2CO and DCN are detected toward 2/5 and 1/5 disks, respectively. For disks with resolved (CO)-O-18, C2H, HCN, and H2CO emission, we observe substructures similar to those previously found in disks around solar-type stars (e.g., rings, holes, and plateaus). C2H and HCN excitation conditions estimated interior to the pebble disk edge for the bright disk J1100-7619 are consistent with previous measurements around solar-type stars. The correlation previously found between C2H and HCN fluxes for solar-type disks extends to our M4-M5 disk sample, but the typical C2H/HCN ratio is higher for the M4-M5 disk sample. This latter finding is reminiscent of the hydrocarbon enhancements found by previous observational infrared surveys in the innermost (<10 au) regions of M-star disks, which is intriguing since our disk-averaged fluxes are heavily influenced by flux levels in the outermost disk, exterior to the pebble disk edge. Overall, most of the observable chemistry at 10-100 au appears similar for solar-type and M4-M5 disks, but hydrocarbons may be more abundant around the cooler stars.
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    CO Line Emission Surfaces and Vertical Structure in Midinclination Protoplanetary Disks
    (2022) Law, Charles J.; Crystian, Sage; Teague, Richard; Oberg, Karin, I; Rich, Evan A.; Andrews, Sean M.; Bae, Jaehan; Flaherty, Kevin; Guzman, Viviana V.; Huang, Jane; Ilee, John D.; Kastner, Joel H.; Loomis, Ryan A.; Long, Feng; Perez, Laura M.; Perez, Sebastian; Qi, Chunhua; Rosotti, Giovanni P.; Ruiz-Rodriguez, Dary; Tsukagoshi, Takashi; Wilner, David J.
    High spatial resolution CO observations of midinclination (approximate to 30 degrees-75 degrees) protoplanetary disks offer an opportunity to study the vertical distribution of CO emission and temperature. The asymmetry of line emission relative to the disk major axis allows for a direct mapping of the emission height above the midplane, and for optically thick, spatially resolved emission in LTE, the intensity is a measure of the local gas temperature. Our analysis of Atacama Large Millimeter/submillimeter Array archival data yields CO emission surfaces, dynamically constrained stellar host masses, and disk atmosphere gas temperatures for the disks around the following: HD 142666, MY Lup, V4046 Sgr, HD 100546, GW Lup, WaOph 6, DoAr 25, Sz 91, CI Tau, and DM Tau. These sources span a wide range in stellar masses (0.50-2.10 M (circle dot)), ages (similar to 0.3-23 Myr), and CO gas radial emission extents (approximate to 200-1000 au). This sample nearly triples the number of disks with mapped emission surfaces and confirms the wide diversity in line emitting heights (z/r approximate to 0.1 to greater than or similar to 0.5) hinted at in previous studies. We compute the radial and vertical CO gas temperature distributions for each disk. A few disks show local temperature dips or enhancements, some of which correspond to dust substructures or the proposed locations of embedded planets. Several emission surfaces also show vertical substructures, which all align with rings and gaps in the millimeter dust. Combining our sample with literature sources, we find that CO line emitting heights weakly decline with stellar mass and gas temperature, which, despite large scatter, is consistent with simple scaling relations. We also observe a correlation between CO emission height and disk size, which is due to the flared structure of disks. Overall, CO emission surfaces trace approximate to 2-5x gas pressure scale heights (H-g) and could potentially be calibrated as empirical tracers of H-g.
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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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    Detection of Dimethyl Ether in the Central Region of the MWC 480 Protoplanetary Disk
    (2024) Yamato, Yoshihide; Aikawa, Yuri; Guzman, Viviana V.; Furuya, Kenji; Notsu, Shota; Cataldi, Gianni; Oeberg, Karin I.; Qi, Chunhua; Law, Charles J.; Huang, Jane; Teague, Richard; Le Gal, Romane
    Characterizing the chemistry of complex organic molecules (COMs) at the epoch of planet formation provides insights into the chemical evolution of the interstellar medium (ISM) and the origin of organic materials in our solar system. We report a detection of dimethyl ether (CH3OCH3) in the disk around the Herbig Ae star MWC 480 with sensitive Atacama Large Millimeter/submillimeter Array observations. This is the first detection of CH3OCH3 in a nontransitional Class II disk. The spatially unresolved, compact (less than or similar to 25 au in radius) nature, broad line width (similar to 30 km s-1), and high excitation temperature (similar to 200 K) indicate the sublimation of COMs in the warm inner disk. Despite the detection of CH3OCH3, methanol (CH3OH), the most abundant COM in the ISM, has not been detected, from which we constrain the column density ratio of CH3OCH3/CH3OH greater than or similar to 7. This high ratio may indicate the reprocessing of COMs during the disk phase, as well as the effect of the physical structure in the inner disk. We also find that this ratio is higher than in COM-rich transition disks recently discovered. This may indicate that in the full disk of MWC 480, COMs have experienced substantial chemical reprocessing in the innermost region, while the COM emission in the transition disks predominantly traces the inherited ice sublimating at the dust cavity edge located at larger radii (greater than or similar to 20 au).
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    Exploring the Complex Ionization Environment of the Turbulent DM Tau Disk
    (2024) Long, Deryl E.; Cleeves, L. Ilsedore; Adams, Fred C.; Andrews, Sean; Bergin, Edwin A.; Guzman, Viviana V.; Huang, Jane; Hughes, A. Meredith; Qi, Chunhua; Schwarz, Kamber; Simon, Jacob B.; Wilner, David
    Ionization drives important chemical and dynamical processes within protoplanetary disks, including the formation of organics and water in the cold midplane and the transportation of material via accretion and magnetohydrodynamic flows. Understanding these ionization-driven processes is crucial for understanding disk evolution and planet formation. We use new and archival Atacama Large Millimeter/submillimeter Array observations of HCO+, H13CO+, and N2H+ to produce the first forward-modeled 2D ionization constraints for the DM Tau protoplanetary disk. We include ionization from multiple sources and explore the disk chemistry under a range of ionizing conditions. Abundances from our 2D chemical models are postprocessed using non-LTE radiative transfer, visibility sampling, and imaging, and are compared directly to the observed radial emission profiles. The observations are best fit by a modestly reduced cosmic-ray ionization rate (zeta CR similar to 10-18 s-1) and a hard X-ray spectrum (hardness ratio = 0.3), which we associate with stellar flaring conditions. Our best-fit model underproduces emission in the inner disk, suggesting that there may be an additional mechanism enhancing ionization in DM Tau's inner disk. Overall, our findings highlight the complexity of ionization in protoplanetary disks and the need for high-resolution multiline studies.
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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.
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    Molecules with ALMA at Planet-forming Scales (MAPS). I. Program Overview and Highlights
    (2021) Oberg, Karin, I; Guzman, Viviana V.; Walsh, Catherine; Aikawa, Yuri; Bergin, Edwin A.; Law, Charles J.; Loomis, Ryan A.; Alarcon, Felipe; Andrews, Sean M.; Bae, Jaehan; Bergner, Jennifer B.; Boehler, Yann; Booth, Alice S.; Bosman, Arthur D.; Calahan, Jenny K.; Cataldi, Gianni; Cleeves, L. Ilsedore; Czekala, Ian; Furuya, Kenji; Huang, Jane; Ilee, John D.; Kurtovic, Nicolas T.; Le Gal, Romane; Liu, Yao; Long, Feng; Menard, Francois; Nomura, Hideko; Perez, Laura M.; Qi, Chunhua; Schwarz, Kamber R.; Sierra, Anibal; Teague, Richard; Tsukagoshi, Takashi; Yamato, Yoshihide; van't Hoff, Merel L. R.; Waggoner, Abygail R.; Wilner, David J.; Zhang, Ke
    Planets form and obtain their compositions in dust- and gas-rich disks around young stars, and the outcome of this process is intimately linked to the disk chemical properties. The distributions of molecules across disks regulate the elemental compositions of planets, including C/N/O/S ratios and metallicity (O/H and C/H), as well as access to water and prebiotically relevant organics. Emission from molecules also encodes information on disk ionization levels, temperature structures, kinematics, and gas surface densities, which are all key ingredients of disk evolution and planet formation models. The Molecules with ALMA at Planet-forming Scales (MAPS) ALMA Large Program was designed to expand our understanding of the chemistry of planet formation by exploring disk chemical structures down to 10 au scales. The MAPS program focuses on five disks-around IM Lup, GM Aur, AS 209, HD 163296, and MWC 480-in which dust substructures are detected and planet formation appears to be ongoing. We observed these disks in four spectral setups, which together cover similar to 50 lines from over 20 different species. This paper introduces the Astrophysical Journal Supplement's MAPS Special Issue by presenting an overview of the program motivation, disk sample, observational details, and calibration strategy. We also highlight key results, including discoveries of links between dust, gas, and chemical substructures, large reservoirs of nitriles and other organics in the inner disk regions, and elevated C/O ratios across most disks. We discuss how this collection of results is reshaping our view of the chemistry of planet formation.
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    Molecules with ALMA at Planet-forming Scales (MAPS). II. CLEAN Strategies for Synthesizing Images of Molecular Line Emission in Protoplanetary Disks
    (2021) Czekala, Ian; Loomis, Ryan A.; Teague, Richard; Booth, Alice S.; Huang, Jane; Cataldi, Gianni; Ilee, John D.; Law, Charles J.; Walsh, Catherine; Bosman, Arthur D.; Guzman, Viviana V.; Gal, Romane Le; Oberg, Karin I.; Yamato, Yoshihide; Aikawa, Yuri; Andrews, Sean M.; Bae, Jaehan; Bergin, Edwin A.; Bergner, Jennifer B.; Cleeves, L. Ilsedore; Kurtovic, Nicolas T.; Menard, Francois; Nomura, Hideko; Perez, Laura M.; Qi, Chunhua; Schwarz, Kamber R.; Tsukagoshi, Takashi; Waggoner, Abygail R.; Wilner, David J.; Zhang, Ke
    The Molecules with ALMA at Planet-forming Scales Large Program (MAPS LP) surveyed the chemical structures of five protoplanetary disks across more than 40 different spectral lines at high angular resolution (0.'' 15 and 0.'' 30 beams for Bands 6 and 3, respectively) and sensitivity (spanning 0.3-1.3 mJy beam(-1) and 0.4-1.9 mJy beam(-1) for Bands 6 and 3, respectively). In this article, we describe the multistage workflow-built around the CASA tclean image deconvolution procedure-that we used to generate the core data product of the MAPS LP: the position-position-velocity image cubes for each spectral line. Owing to the expansive nature of the survey, we encountered a range of imaging challenges: some are familiar to the submillimeter protoplanetary disk community, like the need to use an accurate CLEAN mask, and others are less well known, like the incorrect default flux scaling of the CLEAN residual map first described by Jorsater & van Moorsel (the "JvM effect"). We distill lessons learned into recommended workflows for synthesizing image cubes of molecular emission. In particular, we describe how to produce image cubes with accurate fluxes via "JvM correction," a procedure that is generally applicable to any image synthesized via CLEAN deconvolution but is especially critical for low signal-to-noise ratio (S/N) emission. We further explain how we used visibility tapering to promote a common, fiducial beam size and contextualize the interpretation of S/N when detecting molecular emission from protoplanetary disks. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
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    Molecules with ALMA at Planet-forming Scales (MAPS). III. Characteristics of Radial Chemical Substructures
    (2021) Law, Charles J.; Loomis, Ryan A.; Teague, Richard; Oberg, Karin, I; Czekala, Ian; Andrews, Sean M.; Huang, Jane; Aikawa, Yuri; Alarcon, Felipe; Bae, Jaehan; Bergin, Edwin A.; Bergner, Jennifer B.; Boehler, Yann; Booth, Alice S.; Bosman, Arthur D.; Calahan, Jenny K.; Cataldi, Gianni; Cleeves, L. Ilsedore; Furuya, Kenji; Guzman, Viviana V.; Ilee, John D.; Le Gal, Romane; Liu, Yao; Long, Feng; Menard, Francois; Nomura, Hideko; Qi, Chunhua; Schwarz, Kamber R.; Sierra, Anibal; Tsukagoshi, Takashi; Yamato, Yoshihide; van't Hoff, Merel L. R.; Walsh, Catherine; Wilner, David J.; Zhang, Ke
    The Molecules with ALMA at Planet-forming Scales (MAPS) Large Program provides a detailed, high-resolution (similar to 10-20 au) view of molecular line emission in five protoplanetary disks at spatial scales relevant for planet formation. Here we present a systematic analysis of chemical substructures in 18 molecular lines toward the MAPS sources: IM Lup, GM Aur, AS 209, HD 163296, and MWC 480. We identify more than 200 chemical substructures, which are found at nearly all radii where line emission is detected. A wide diversity of radial morphologies-including rings, gaps, and plateaus-is observed both within each disk and across the MAPS sample. This diversity in line emission profiles is also present in the innermost 50 au. Overall, this suggests that planets form in varied chemical environments both across disks and at different radii within the same disk. Interior to 150 au, the majority of chemical substructures across the MAPS disks are spatially coincident with substructures in the millimeter continuum, indicative of physical and chemical links between the disk midplane and warm, elevated molecular emission layers. Some chemical substructures in the inner disk and most chemical substructures exterior to 150 au cannot be directly linked to dust substructure, however, which indicates that there are also other causes of chemical substructures, such as snowlines, gradients in UV photon fluxes, ionization, and radially varying elemental ratios. This implies that chemical substructures could be developed into powerful probes of different disk characteristics, in addition to influencing the environments within which planets assemble. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
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    Molecules with ALMA at Planet-forming Scales (MAPS). IV. Emission Surfaces and Vertical Distribution of Molecules
    (2021) Law, Charles J.; Teague, Richard; Loomis, Ryan A.; Bae, Jaehan; Oberg, Karin, I; Czekala, Ian; Andrews, Sean M.; Aikawa, Yuri; Alarcon, Felipe; Bergin, Edwin A.; Bergner, Jennifer B.; Booth, Alice S.; Bosman, Arthur D.; Calahan, Jenny K.; Cataldi, Gianni; Cleeves, L. Ilsedore; Furuya, Kenji; Guzman, Viviana V.; Huang, Jane; Ilee, John D.; Le Gal, Romane; Liu, Yao; Long, Feng; Menard, Francois; Nomura, Hideko; Perez, Laura M.; Qi, Chunhua; Schwarz, Kamber R.; Soto, Daniela; Tsukagoshi, Takashi; Yamato, Yoshihide; 't Hoff, Merel L. R. van; Walsh, Catherine; Wilner, David J.; Zhang, Ke
    The Molecules with ALMA at Planet-forming Scales (MAPS) Large Program provides a unique opportunity to study the vertical distribution of gas, chemistry, and temperature in the protoplanetary disks around IM Lup, GM Aur, AS 209, HD 163296, and MWC 480. By using the asymmetry of molecular line emission relative to the disk major axis, we infer the emission height (z) above the midplane as a function of radius (r). Using this method, we measure emitting surfaces for a suite of CO isotopologues, HCN, and C2H. We find that (CO)-C-12 emission traces the most elevated regions with z/r> 0.3
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    Molecules with ALMA at Planet-forming Scales (MAPS). IX. Distribution and Properties of the Large Organic Molecules HC3N, CH3CN, and c-C3H2
    (2021) Ilee, John D.; Walsh, Catherine; Booth, Alice S.; Aikawa, Yuri; Andrews, Sean M.; Bae, Jaehan; Bergin, Edwin A.; Bergner, Jennifer B.; Bosman, Arthur D.; Cataldi, Gianni; Cleeves, L. Ilsedore; Czekala, Ian; Guzman, Viviana V.; Huang, Jane; Law, Charles J.; Le Gal, Romane; Loomis, Ryan A.; Menard, Francois; Nomura, Hideko; Oberg, Karin, I; Qi, Chunhua; Schwarz, Kamber R.; Teague, Richard; Tsukagoshi, Takashi; Wilner, David J.; Yamato, Yoshihide; Zhang, Ke
    The precursors to larger, biologically relevant molecules are detected throughout interstellar space, but determining the presence and properties of these molecules during planet formation requires observations of protoplanetary disks at high angular resolution and sensitivity. Here, we present 0.'' 3 observations of HC3N, CH3CN, and c-C3H2 in five protoplanetary disks observed as part of the Molecules with ALMA at Planet-forming Scales (MAPS) Large Program. We robustly detect all molecules in four of the disks (GM Aur, AS 209, HD 163296, and MWC 480) with tentative detections of c-C3H2 and CH3CN in IM Lup. We observe a range of morphologies-central peaks, single or double rings-with no clear correlation in morphology between molecule or disk. Emission is generally compact and on scales comparable with the millimeter dust continuum. We perform both disk-integrated and radially resolved rotational diagram analysis to derive column densities and rotational temperatures. The latter reveals 5-10 times more column density in the inner 50-100 au of the disks when compared with the disk-integrated analysis. We demonstrate that CH3CN originates from lower relative heights in the disks when compared with HC3N, in some cases directly tracing the disk midplane. Finally, we find good agreement between the ratio of small to large nitriles in the outer disks and comets. Our results indicate that the protoplanetary disks studied here are host to significant reservoirs of large organic molecules, and that this planet- and comet-building material can be chemically similar to that in our own solar system. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
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    Molecules with ALMA at Planet-forming Scales (MAPS). V. CO Gas Distributions
    (2021) Zhang, Ke; Booth, Alice S.; Law, Charles J.; Bosman, Arthur D.; Schwarz, Kamber R.; Bergin, Edwin A.; Oberg, Karin, I; Andrews, Sean M.; Guzman, Viviana V.; Walsh, Catherine; Qi, Chunhua; van 't Hoff, Merel L. R.; Long, Feng; Wilner, David J.; Huang, Jane; Czekala, Ian; Ilee, John D.; Cataldi, Gianni; Bergner, Jennifer B.; Aikawa, Yuri; Teague, Richard; Bae, Jaehan; Loomis, Ryan A.; Calahan, Jenny K.; Alarcon, Felipe; Menard, Francois; Le Gal, Romane; Sierra, Anibal; Yamato, Yoshihide; Nomura, Hideko; Tsukagoshi, Takashi; Perez, Laura M.; Trapman, Leon; Liu, Yao; Furuya, Kenji
    Here we present high-resolution (15-24 au) observations of CO isotopologue lines from the Molecules with ALMA on Planet-forming Scales (MAPS) ALMA Large Program. Our analysis employs observations of the (J = 2-1) and (1-0) lines of (CO)-C-13 and (CO)-O-18 and the (J = 1-0) line of (CO)-O-17 for five protoplanetary disks. We retrieve CO gas density distributions, using three independent methods: (1) a thermochemical modeling framework based on the CO data, the broadband spectral energy distribution, and the millimeter continuum emission; (2) an empirical temperature distribution based on optically thick CO lines; and (3) a direct fit to the (CO)-O-17 hyperfine lines. Results from these methods generally show excellent agreement. The CO gas column density profiles of the five disks show significant variations in the absolute value and the radial shape. Assuming a gas-to-dust mass ratio of 100, all five disks have a global CO-to-H-2 abundance 10-100 times lower than the interstellar medium ratio. The CO gas distributions between 150 and 400 au match well with models of viscous disks, supporting the long-standing theory. CO gas gaps appear to be correlated with continuum gap locations, but some deep continuum gaps do not have corresponding CO gaps. The relative depths of CO and dust gaps are generally consistent with predictions of planet-disk interactions, but some CO gaps are 5-10 times shallower than predictions based on dust gaps. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
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    Molecules with ALMA at Planet-forming Scales (MAPS). VI. Distribution of the Small Organics HCN, C2H, and H2CO
    (2021) Guzman, Viviana V.; Bergner, Jennifer B.; Law, Charles J.; Oberg, Karin I.; Walsh, Catherine; Cataldi, Gianni; Aikawa, Yuri; Bergin, Edwin A.; Czekala, Ian; Huang, Jane; Andrews, Sean M.; Loomis, Ryan A.; Zhang, Ke; Le Gal, Romane; Alarcon, Felipe; Ilee, John D.; Teague, Richard; Cleeves, L. Ilsedore; Wilner, David J.; Long, Feng; Schwarz, Kamber R.; Bosman, Arthur D.; Perez, Laura M.; Menard, Francois; Liu, Yao
    Small organic molecules, such as C2H, HCN, and H2CO, are tracers of the C, N, and O budget in protoplanetary disks. We present high-angular-resolution (10-50 au) observations of C2H, HCN, and H2CO lines in five protoplanetary disks from the Molecules with ALMA at Planet-forming Scales (MAPS) ALMA Large Program. We derive column density and excitation temperature profiles for HCN and C2H, and find that the HCN emission arises in a temperate (20-30 K) layer in the disk, while C2H is present in relatively warmer (20-60 K) layers. In the case of HD 163296, we find a decrease in column density for HCN and C2H inside one of the dust gaps near similar to 83 au, where a planet has been proposed to be located. We derive H2CO column density profiles assuming temperatures between 20 and 50 K, and find slightly higher column densities in the colder disks around T Tauri stars than around Herbig Ae stars. The H2CO column densities rise near the location of the CO snowline and/or millimeter dust edge, suggesting an efficient release of H2CO ices in the outer disk. Finally, we find that the inner 50 au of these disks are rich in organic species, with abundances relative to water that are similar to cometary values. Comets could therefore deliver water and key organics to future planets in these disks, similar to what might have happened here on Earth. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
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    Molecules with ALMA at Planet-forming Scales (MAPS). VII. Substellar O/H and C/H and Superstellar C/O in Planet-feeding Gas
    (2021) Bosman, Arthur D.; Alarcon, Felipe; Bergin, Edwin A.; Zhang, Ke; Van't Hoff, Merel L. R.; Oberg, Karin I.; Guzman, Viviana V.; Walsh, Catherine; Aikawa, Yuri; Andrews, Sean M.; Bergner, Jennifer B.; Booth, Alice S.; Cataldi, Gianni; Cleeves, L. Ilsedore; Czekala, Ian; Furuya, Kenji; Huang, Jane; Ilee, John D.; Law, Charles J.; Le Gal, Romane; Liu, Yao; Long, Feng; Loomis, Ryan A.; Menard, Francois; Nomura, Hideko; Qi, Chunhua; Schwarz, Kamber R.; Teague, Richard; Tsukagoshi, Takashi; Yamato, Yoshihide; Wilner, David J.
    The elemental composition of the gas and dust in a protoplanetary disk influences the compositions of the planets that form in it. We use the Molecules with ALMA at Planet-forming Scales (MAPS) data to constrain the elemental composition of the gas at the locations of potentially forming planets. The elemental abundances are inferred by comparing source-specific gas-grain thermochemical models with variable C/O ratios and small-grain abundances from the DALI code with CO and C2H column densities derived from the high-resolution observations of the disks of AS 209, HD 163296, and MWC 480. Elevated C/O ratios (similar to 2.0), even within the CO ice line, are necessary to match the inferred C2H column densities over most of the pebble disk. Combined with constraints on the CO abundances in these systems, this implies that both the O/H and C/H ratios in the gas are substellar by a factor of 4-10, with the O/H depleted by a factor of 20-50, resulting in the high C/O ratios. This necessitates that even within the CO ice line, most of the volatile carbon and oxygen is still trapped on grains in the midplane. Planets accreting gas in the gaps of the AS 209, HD 163296, and MWC 480 disks will thus acquire very little carbon and oxygen after reaching the pebble isolation mass. In the absence of atmosphere-enriching events, these planets would thus have a strongly substellar O/H and C/H and superstellar C/O atmospheric composition. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
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    Molecules with ALMA at Planet-forming Scales (MAPS). X. Studying Deuteration at High Angular Resolution toward Protoplanetary Disks
    (2021) Cataldi, Gianni; Yamato, Yoshihide; Aikawa, Yuri; Bergner, Jennifer B.; Furuya, Kenji; Guzman, Viviana V.; Huang, Jane; Loomis, Ryan A.; Qi, Chunhua; Andrews, Sean M.; Bergin, Edwin A.; Booth, Alice S.; Bosman, Arthur D.; Cleeves, L. Ilsedore; Czekala, Ian; Ilee, John D.; Law, Charles J.; Le Gal, Romane; Liu, Yao; Long, Feng; Menard, Francois; Nomura, Hideko; Oberg, Karin, I; Schwarz, Kamber R.; Teague, Richard; Tsukagoshi, Takashi; Walsh, Catherine; Wilner, David J.; Zhang, Ke
    Deuterium fractionation is dependent on various physical and chemical parameters. Thus, the formation location and thermal history of material in the solar system is often studied by measuring its D/H ratio. This requires knowledge about the deuteration processes operating during the planet formation era. We aim to study these processes by radially resolving the DCN/HCN (at 0.'' 3 resolution) and N2D+/N2H+ (similar to 0.'' 3-0.'' 9) column density ratios toward the five protoplanetary disks observed by the Molecules with ALMA at Planet-forming scales (MAPS) Large Program. DCN is detected in all five sources, with one newly reported detection. N2D+ is detected in four sources, two of which are newly reported detections. We derive column density profiles that allow us to study the spatial variation of the DCN/HCN and N2D+/N2H+ ratios at high resolution. DCN/HCN varies considerably for different parts of the disks, ranging from 10(-3) to 10(-1). In particular, the inner-disk regions generally show significantly lower HCN deuteration compared with the outer disk. In addition, our analysis confirms that two deuterium fractionation channels are active, which can alter the D/H ratio within the pool of organic molecules. N2D+ is found in the cold outer regions beyond similar to 50 au, with N2D+/N2H+ ranging between 10(-2) and 1 across the disk sample. This is consistent with the theoretical expectation that N2H+ deuteration proceeds via the low-temperature channel only. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
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    Molecules with ALMA at Planet-forming Scales (MAPS). XI. CN and HCN as Tracers of Photochemistry in Disks
    (2021) Bergner, Jennifer B.; Oberg, Karin I.; Guzman, Viviana V.; Law, Charles J.; Loomis, Ryan A.; Cataldi, Gianni; Bosman, Arthur D.; Aikawa, Yuri; Andrews, Sean M.; Bergin, Edwin A.; Booth, Alice S.; Cleeves, L. Ilsedore; Czekala, Ian; Huang, Jane; Ilee, John D.; Le Gal, Romane; Long, Feng; Nomura, Hideko; Menard, Francois; Qi, Chunhua; Schwarz, Kamber R.; Teague, Richard; Tsukagoshi, Takashi; Walsh, Catherine; Wilner, David J.; Yamato, Yoshihide
    UV photochemistry in the surface layers of protoplanetary disks dramatically alters their composition relative to previous stages of star formation. The abundance ratio CN/HCN has long been proposed to trace the UV field in various astrophysical objects; however, to date the relationship between CN, HCN, and the UV field in disks remains ambiguous. As part of the ALMA Large Program MAPS (Molecules with ALMA at Planet-forming Scales), we present observations of CN N = 1-0 transitions at 0.'' 3 resolution toward five disk systems. All disks show bright CN emission within similar to 50-150 au, along with a diffuse emission shelf extending up to 600 au. In all sources we find that the CN/HCN column density ratio increases with disk radius from about unity to 100, likely tracing increased UV penetration that enhances selective HCN photodissociation in the outer disk. Additionally, multiple millimeter dust gaps and rings coincide with peaks and troughs, respectively, in the CN/HCN ratio, implying that some millimeter substructures are accompanied by changes to the UV penetration in more elevated disk layers. That the CN/HCN ratio is generally high (>1) points to a robust photochemistry shaping disk chemical compositions and also means that CN is the dominant carrier of the prebiotically interesting nitrile group at most disk radii. We also find that the local column densities of CN and HCN are positively correlated despite emitting from vertically stratified disk regions, indicating that different disk layers are chemically linked. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
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    Molecules with ALMA at Planet-forming Scales (MAPS). XII. Inferring the C/O and S/H Ratios in Protoplanetary Disks with Sulfur Molecules
    (2021) Le Gal, Romane; Oberg, Karin, I; Teague, Richard; Loomis, Ryan A.; Law, Charles J.; Walsh, Catherine; Bergin, Edwin A.; Menard, Francois; Wilner, David J.; Andrews, Sean M.; Aikawa, Yuri; Booth, Alice S.; Cataldi, Gianni; Bergner, Jennifer B.; Bosman, Arthur D.; Cleeves, L. Ilsedore; Czekala, Ian; Furuya, Kenji; Guzman, Viviana V.; Huang, Jane; Ilee, John D.; Nomura, Hideko; Qi, Chunhua; Schwarz, Kamber R.; Tsukagoshi, Takashi; Yamato, Yoshihide; Zhang, Ke
    Sulfur-bearing molecules play an important role in prebiotic chemistry and planet habitability. They are also proposed probes of chemical ages, elemental C/O ratio, and grain chemistry processing. Commonly detected in diverse astrophysical objects, including the solar system, their distribution and chemistry remain, however, largely unknown in planet-forming disks. We present CS (2 - 1) observations at similar to 0.'' 3 resolution performed within the ALMA MAPS Large Program toward the five disks around IM Lup, GM Aur, AS 209, HD 163296, and MWC 480. CS is detected in all five disks, displaying a variety of radial intensity profiles and spatial distributions across the sample, including intriguing apparent azimuthal asymmetries. Transitions of C2S and SO were also serendipitously covered, but only upper limits are found. For MWC 480, we present complementary ALMA observations at similar to 0.'' 5 of CS, (CS)-C-13, (CS)-S-34, H2CS, OCS, and SO2. We find a column density ratio N(H2CS)/N(CS) similar to 2/3, suggesting that a substantial part of the sulfur reservoir in disks is in organic form (i.e., C (x) H (y) S (z) ). Using astrochemical disk modeling tuned to MWC 480, we demonstrate that N(CS)/N(SO) is a promising probe for the elemental C/O ratio. The comparison with the observations provides a supersolar C/O. We also find a depleted gas-phase S/H ratio, suggesting either that part of the sulfur reservoir is locked in solid phase or that it remains in an unidentified gas-phase reservoir. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.