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Browsing by Author "Long, Feng"

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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.
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.
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.
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.
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.
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
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.
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.
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.
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.
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.
Molecules with ALMA at Planet-forming Scales (MAPS). XIV. Revealing Disk Substructures in Multiwavelength Continuum Emission
(2021) Sierra, Anibal; Perez, Laura M.; Zhang, Ke; Law, Charles J.; Guzman, Viviana V.; Qi, Chunhua; Bosman, Arthur D.; Oberg, Karin, I; Andrews, Sean M.; Long, Feng; Teague, Richard; Booth, Alice S.; Walsh, Catherine; Wilner, David J.; Menard, Francois; Cataldi, Gianni; Czekala, Ian; Bae, Jaehan; Huang, Jane; Bergner, Jennifer B.; Ilee, John D.; Benisty, Myriam; Le Gal, Romane; Loomis, Ryan A.; Tsukagoshi, Takashi; Liu, Yao; Yamato, Yoshihide; Aikawa, Yuri
Constraining dust properties of planet-forming disks via high-angular-resolution observations is fundamental to understanding how solids are trapped in substructures and how dust growth may be favored or accelerated therein. We use ALMA dust continuum observations of the Molecules with ALMA at Planet-forming Scales (MAPS) disks and explore a large parameter space to constrain the radial distribution of solid mass and maximum grain size in each disk, including or excluding dust scattering. In the nonscattering model, the dust surface density and maximum grain size profiles decrease from the inner disks to the outer disks, with local maxima at the bright ring locations, as expected from dust trapping models. The inferred maximum grain sizes from the inner to outer disks decrease from 1 cm to 1 mm. For IM Lup, HD 163296, and MWC 480 in the scattering model, two solutions are compatible with their observed inner disk emission: one solution corresponding to a maximum grain size of a few millimeters (similar to the nonscattering model), and the other corresponding to a size of a few hundred micrometers. Based on the estimated Toomre parameter, only IM Lup-which shows a prominent spiral morphology in millimeter dust-is found to be gravitationally unstable. The estimated maximum Stokes number in all the disks lies between 0.01 and 0.3, and the estimated turbulence parameters in the rings of AS 209 and HD 163296 are close to the threshold where dust growth is limited by turbulent fragmentation. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
Molecules with ALMA at Planet-forming Scales (MAPS). XIX. Spiral Arms, a Tail, and Diffuse Structures Traced by CO around the GM Aur Disk
(2021) Huang, Jane; Bergin, Edwin A.; Oberg, Karin, I; Andrews, Sean M.; Teague, Richard; Law, Charles J.; Kalas, Paul; Aikawa, Yuri; Bae, Jaehan; Bergner, Jennifer B.; Booth, Alice S.; Bosman, Arthur D.; Calahan, Jenny K.; Cataldi, Gianni; Cleeves, L. Ilsedore; Czekala, Ian; Ilee, John D.; Le Gal, Romane; Guzman, Viviana V.; Long, Feng; Loomis, Ryan A.; Menard, Francois; Nomura, Hideko; Qi, Chunhua; Schwarz, Kamber R.; Tsukagoshi, Takashi; van't Hoff, Merel L. R.; Walsh, Catherine; Wilner, David J.; Yamato, Yoshihide; Zhang, Ke
The concentric gaps and rings commonly observed in protoplanetary disks in millimeter continuum emission have lent the impression that planet formation generally proceeds within orderly, isolated systems. While deep observations of spatially resolved molecular emission have been comparatively limited, they are increasingly suggesting that some disks interact with their surroundings while planet formation is underway. We present an analysis of complex features identified around GM Aur in (CO)-C-12 J = 2 - 1 images at a spatial resolution of similar to 40 au. In addition to a Keplerian disk extending to a radius of similar to 550 au, the CO emission traces flocculent spiral arms out to radii of similar to 1200 au, a tail extending similar to 1800 au southwest of GM Aur, and diffuse structures extending from the north side of the disk up to radii of similar to 1900 au. The diffuse structures coincide with a "dust ribbon" previously identified in scattered light. The large-scale asymmetric gas features present a striking contrast with the mostly axisymmetric, multi-ringed millimeter continuum tracing the pebble disk. We hypothesize that GM Aur's complex gas structures result from late infall of remnant envelope or cloud material onto the disk. The morphological similarities to the SU Aur and AB Aur systems, which are also located in the L1517 cloud, provide additional support to a scenario in which interactions with the environment are playing a role in regulating the distribution and transport of material in all three of these Class II disk systems. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
Molecules with ALMA at Planet-forming Scales (MAPS). XV. Tracing Protoplanetary Disk Structure within 20 au
(2021) Bosman, Arthur D.; Bergin, Edwin A.; Loomis, Ryan A.; Andrews, Sean M.; Van't Hoff, Merel L. R.; Teague, Richard; Oberg, Karin, I; Guzman, Viviana V.; Walsh, Catherine; Aikawa, Yuri; Alarcon, Felipe; Bae, Jaehan; Bergner, Jennifer B.; Booth, Alice S.; Cataldi, Gianni; Cleeves, L. Ilsedore; Czekala, Ian; Huang, Jane; Ilee, John D.; Law, Charles J.; Le Gal, Romane; Liu, Yao; Long, Feng; Menard, Francois; Nomura, Hideko; Perez, Laura M.; Qi, Chunhua; Schwarz, Kamber R.; Sierra, Anibal; Tsukagoshi, Takashi; Yamato, Yoshihide; Wilner, David J.; Zhang, Ke
Constraining the distribution of gas and dust in the inner 20 au of protoplanetary disks is difficult. At the same time, this region is thought to be responsible for most planet formation, especially around the water ice line at 3-10 au. Under the assumption that the gas is in a Keplerian disk, we use the exquisite sensitivity of the Molecules with ALMA at Planet-forming Scales (MAPS) ALMA large program to construct radial surface brightness profiles with a similar to 3 au effective resolution for the CO isotopologue J = 2-1 lines using the line velocity profile. IM Lup reveals a central depression in (CO)-C-13 and (CO)-O-18 that is ascribed to a pileup of similar to 500 M (circle plus) of dust in the inner 20 au, leading to a gas-to-dust ratio of around <10. This pileup is consistent with an efficient drift of grains (greater than or similar to 100 M (circle plus) Myr(-1)) and a local gas-to-dust ratio that suggests that the streaming instability could be active. The CO isotopologue emission in the GM Aur disk is consistent with a small (similar to 15 au), strongly depleted gas cavity within the similar to 40 au dust cavity. The radial surface brightness profiles for both the AS 209 and HD 163296 disks show a local minimum and maximum in the (CO)-O-18 emission at the location of a known dust ring (similar to 14 au) and gap (similar to 10 au), respectively. This indicates that the dust ring has a low gas-to-dust ratio (>10) and that the dust gap is gas-rich enough to have optically thick (CO)-O-18. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
Molecules with ALMA at Planet-forming Scales (MAPS). XVI. Characterizing the Impact of the Molecular Wind on the Evolution of the HD 163296 System
(2021) Booth, Alice S.; Tabone, Benoit; Ilee, John D.; Walsh, Catherine; Aikawa, Yuri; Andrews, Sean M.; Bae, Jaehan; Bergin, Edwin A.; Bergner, Jennifer B.; Bosman, Arthur D.; Calahan, Jenny K.; Cataldi, Gianni; Cleeves, L. Ilsedore; Czekala, Ian; Guzman, Viviana V.; Huang, Jane; Law, Charles J.; Le Gal, Romane; Long, Feng; 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
During the main phase of evolution of a protoplanetary disk, accretion regulates the inner-disk properties, such as the temperature and mass distribution, and in turn, the physical conditions associated with planet formation. The driving mechanism behind accretion remains uncertain; however, one promising mechanism is the removal of a fraction of angular momentum via a magnetohydrodynamic (MHD) disk wind launched from the inner tens of astronomical units of the disk. This paper utilizes CO isotopologue emission to study the unique molecular outflow originating from the HD 163296 protoplanetary disk obtained with the Atacama Large Millimeter/submillimeter Array. HD 163296 is one of the most well-studied Class II disks and is proposed to host multiple gas-giant planets. We robustly detect the large-scale rotating outflow in the (CO)-C-12 J = 2 - 1 and the (CO)-C-13 J = 2 - 1 and J = 1 - 0 transitions. We constrain the kinematics, the excitation temperature of the molecular gas, and the mass-loss rate. The high ratio of the rates of ejection to accretion (5-50), together with the rotation signatures of the flow, provides solid evidence for an MHD disk wind. We find that the angular momentum removal by the wind is sufficient to drive accretion though the inner region of the disk; therefore, accretion driven by turbulent viscosity is not required to explain HD 163296's accretion. The low temperature of the molecular wind and its overall kinematics suggest that the MHD disk wind could be perturbed and shocked by the previously observed high-velocity atomic jet. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
Molecules with ALMA at Planet-forming Scales (MAPS). XVII. Determining the 2D Thermal Structure of the HD 163296 Disk
(2021) Calahan, Jenny K.; Bergin, Edwin A.; Zhang, Ke; Schwarz, Kamber R.; Oberg, Karin, I; Guzman, Viviana V.; Walsh, Catherine; Aikawa, Yuri; Alarcon, Felipe; Andrews, Sean M.; Bae, Jaehan; Bergner, Jennifer B.; Booth, Alice S.; Bosman, Arthur D.; Cataldi, Gianni; Czekala, Ian; Huang, Jane; Ilee, John D.; Law, Charles J.; Le Gal, Romane; Long, Feng; Loomis, Ryan A.; Menard, Francois; Nomura, Hideko; Qi, Chunhua; Teague, Richard; van't Hoff, Merel L. R.; Wilner, David J.; Yamato, Yoshihide
Understanding the temperature structure of protoplanetary disks is key to interpreting observations, predicting the physical and chemical evolution of the disk, and modeling planet formation processes. In this study, we constrain the two-dimensional thermal structure of the disk around the Herbig Ae star HD 163296. Using the thermochemical code RAC2D, we derive a thermal structure that reproduces spatially resolved Atacama Large Millimeter/submillimeter Array observations (similar to 0.'' 12 (13 au)-0.'' 25 (26 au)) of (CO)-C-12 J = 2 - 1, (CO)-C-13 J = 1 - 0, 2 - 1, (CO)-O-18 J = 1 - 0, 2 - 1, and (CO)-O-17 J = 1 - 0, the HD J = 1 - 0 flux upper limit, the spectral energy distribution (SED), and continuum morphology. The final model incorporates both a radial depletion of CO motivated by a timescale shorter than typical CO gas-phase chemistry (0.01 Myr) and an enhanced temperature near the surface layer of the the inner disk (z/r >= 0.21). This model agrees with the majority of the empirically derived temperatures and observed emitting surfaces derived from the J = 2 - 1 CO observations. We find an upper limit for the disk mass of 0.35 M (circle dot), using the upper limit of the HD J = 1 - 0 and J = 2 - 1 flux. With our final thermal structure, we explore the impact that gaps have on the temperature structure constrained by observations of the resolved gaps. Adding a large gap in the gas and small dust additionally increases gas temperature in the gap by only 5%-10%. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
Molecules with ALMA at Planet-forming Scales (MAPS). XVIII. Kinematic Substructures in the Disks of HD 163296 and MWC 480
(2021) Teague, Richard; Bae, Jaehan; Aikawa, Yuri; Andrews, Sean M.; Bergin, Edwin A.; Bergner, Jennifer B.; Boehler, Yann; Booth, Alice S.; Bosman, Arthur D.; Cataldi, Gianni; Czekala, Ian; Guzman, Viviana V.; Huang, Jane; Ilee, John D.; Law, Charles J.; Le Gal, Romane; Long, Feng; Loomis, Ryan A.; Menard, Francois; Oberg, Karin, I; Perez, Laura M.; Schwarz, Kamber R.; Sierra, Anibal; Walsh, Catherine; Wilner, David J.; Yamato, Yoshihide; Zhang, Ke
We explore the dynamical structure of the protoplanetary disks surrounding HD 163296 and MWC 480 as part of the Molecules with ALMA at Planet-forming Scales (MAPS) large program. Using the J = 2-1 transitions of (CO)-C-12, (CO)-C-13, and (CO)-O-18 imaged at spatial resolutions of similar to 0.'' 15 and with a channel spacing of 200 m s(-1), we find perturbations from Keplerian rotation in the projected velocity fields of both disks (less than or similar to 5% of the local Keplerian velocity), suggestive of large-scale (tens of astronomical units in size), coherent flows. By accounting for the azimuthal dependence on the projection of the velocity field, the velocity fields were decomposed into azimuthally averaged orthogonal components, v ( phi ), v ( r ), and v ( z ). Using the optically thick (CO)-C-12 emission as a probe of the gas temperature, local variations of approximate to 3 K (approximate to 5% relative changes) were observed and found to be associated with the kinematic substructures. The MWC 480 disk hosts a suite of tightly wound spiral arms. The spirals arms, in conjunction with the highly localized perturbations in the gas velocity structure (kinematic planetary signatures), indicate a giant planet, similar to 1 M (Jup), at a radius of approximate to 245 au. In the disk of HD 163296, the kinematic substructures were consistent with previous studies of Pinte et al. and Teague et al. advocating for multiple similar to 1 M (Jup) planets embedded in the disk. These results demonstrate that molecular line observations that characterize the dynamical structure of disks can be used to search for the signatures of embedded planets. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
Molecules with ALMA at Planet-forming Scales (MAPS): A Circumplanetary Disk Candidate in Molecular-line Emission in the AS 209 Disk
(2022) Bae, Jaehan; Teague, Richard; Andrews, Sean M.; Benisty, Myriam; Facchini, Stefano; Galloway-Sprietsma, Maria; Loomis, Ryan A.; Aikawa, Yuri; Alarcon, Felipe; Bergin, Edwin; Bergner, Jennifer B.; Booth, Alice S.; Cataldi, Gianni; Cleeves, L. Ilsedore; Czekala, Ian; Guzman, Viviana V.; Huang, Jane; Ilee, John D.; Kurtovic, Nicolas T.; Law, Charles J.; Le Gal, Romane; Liu, Yao; Long, Feng; Menard, Francois; Oberg, Karin, I; Perez, Laura M.; Qi, Chunhua; Schwarz, Kamber R.; Sierra, Anibal; Walsh, Catherine; Wilner, David J.; Zhang, Ke
We report the discovery of a circumplanetary disk (CPD) candidate embedded in the circumstellar disk of the T Tauri star AS 209 at a radial distance of about 200 au (on-sky separation of 1.'' 4 from the star at a position angle of 161 degrees), isolated via (CO)-C-13 J = 2-1 emission. This is the first instance of CPD detection via gaseous emission capable of tracing the overall CPD mass. The CPD is spatially unresolved with a 117 x 82 mas beam and manifests as a point source in (CO)-C-13, indicating that its diameter is less than or similar to 14 au. The CPD is embedded within an annular gap in the circumstellar disk previously identified using (CO)-C-12 and near-infrared scattered-light observations and is associated with localized velocity perturbations in (CO)-C-12. The coincidence of these features suggests that they have a common origin: an embedded giant planet. We use the (CO)-C-13 intensity to constrain the CPD gas temperature and mass. We find that the CPD temperature is greater than or similar to 35 K, higher than the circumstellar disk temperature at the radial location of the CPD, 22 K, suggesting that heating sources localized to the CPD must be present. The CPD gas mass is greater than or similar to 0.095 M (Jup) similar or equal to 30 M (circle plus) adopting a standard (CO)-C-13 abundance. From the nondetection of millimeter continuum emission at the location of the CPD (3 sigma flux density less than or similar to 26.4 mu Jy), we infer that the CPD dust mass is less than or similar to 0.027 M (circle plus) similar or equal to 2.2 lunar masses, indicating a low dust-to-gas mass ratio of less than or similar to 9 x 10(-4). We discuss the formation mechanism of the CPD-hosting giant planet on a wide orbit in the framework of gravitational instability and pebble accretion.
Molecules with ALMA at Planet-forming Scales (MAPS): Complex Kinematics in the AS 209 Disk Induced by a Forming Planet and Disk Winds
(2023) Galloway-Sprietsma, Maria; Bae, Jaehan; Teague, Richard; Benisty, Myriam; Facchini, Stefano; Aikawa, Yuri; Alarcon, Felipe; Andrews, Sean M.; Bergin, Edwin; Cataldi, Gianni; Cleeves, L. Ilsedore; Czekala, Ian; Guzman, Viviana V.; Huang, Jane; Law, Charles J.; Le Gal, Romane; Liu, Yao; Long, Feng; Menard, Francois; Oberg, Karin I.; Walsh, Catherine; Wilner, David J.
We study the kinematics of the AS 209 disk using the J = 2-1 transitions of (CO)-C-12, (CO)-C-13, and (CO)-O-18. We derive the radial, azimuthal, and vertical velocity of the gas, taking into account the lowered emission surface near the annular gap at similar or equal to 1.'' 7 (200 au) within which a candidate circumplanetary-disk-hosting planet has been reported previously. In (CO)-C-12 and (CO)-C-13, we find a coherent upward flow arising from the gap. The upward gas flow is as fast as 150 m s(-1) in the regions traced by (CO)-C-12 emission, which corresponds to about 50% of the local sound speed or 6% of the local Keplerian speed. Such an upward gas flow is difficult to reconcile with an embedded planet alone. Instead, we propose that magnetically driven winds via ambipolar diffusion are triggered by the low gas density within the planet-carved gap, dominating the kinematics of the gap region. We estimate the ambipolar Elsasser number, Am, using the HCO+ column density as a proxy for ion density and find that Am is similar to 0.1 at the radial location of the upward flow. This value is broadly consistent with the value at which numerical simulations find that ambipolar diffusion drives strong winds. We hypothesize that the activation of magnetically driven winds in a planet-carved gap can control the growth of the embedded planet. We provide a scaling relationship that describes the wind-regulated terminal mass: adopting parameters relevant to 100 au from a solar-mass star, we find that the wind-regulated terminal mass is about one Jupiter mass, which may help explain the dearth of directly imaged super-Jovian-mass planets.
The ASAS-SN bright supernova catalogue - I. 2013-2014
(OXFORD UNIV PRESS, 2017) Holoien, T. W. S.; Stanek, K. Z.; Kochanek, C. S.; Shappee, B. J.; Prieto, J. L.; Brimacombe, J.; Bersier, D.; Bishop, D. W.; Dong, Subo; Brown, J. S.; Danilet, A. B.; Simonian, G. V.; Basu, U.; Beacom, J. F.; Falco, E.; Pojmanski, G.; Skowron, D. M.; Wozniak, P. R.; Avila, C. G.; Conseil, E.; Contreras, C.; Cruz, I.; Fernandez, J. M.; Koff, R. A.; Guo, Zhen; Herczeg, G. J.; Hissong, J.; Hsiao, E. Y.; Jose, J.; Kiyota, S.; Long, Feng; Monard, L. A. G.; Nicholls, B.; Nicolas, J.; Wiethoff, W. S.
We present basic statistics for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) during its first year-and-a-half of operations, spanning 2013 and 2014. We also present the same information for all other bright (mV <= 17), spectroscopically confirmed supernovae discovered from 2014 May 1 through the end of 2014, providing a comparison to the ASAS-SN sample starting from the point where ASAS-SN became operational in both hemispheres. In addition, we present collected redshifts and near-UV through IR magnitudes, where available, for all host galaxies of the bright supernovae in both samples. This work represents a comprehensive catalogue of bright supernovae and their hosts from multiple professional and amateur sources, allowing for population studies that were not previously possible because the all-sky emphasis of ASAS-SN redresses many previously existing biases. In particular, ASAS-SN systematically finds bright supernovae closer to the centres of host galaxies than either other professional surveys or amateurs, a remarkable result given ASAS-SN's poorer angular resolution. This is the first of a series of yearly papers on bright supernovae and their hosts that will be released by the ASAS-SN team.

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