Charles J. Law
A5077328003- Astrophysics and Star Formation Studies
- Molecular Spectroscopy and Structure
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Atmospheric Ozone and Climate
- Gamma-ray bursts and supernovae
- Spectroscopy and Laser Applications
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Advanced Chemical Physics Studies
- Astronomy and Astrophysical Research
- Spacecraft and Cryogenic Technologies
- Thermodynamic properties of mixtures
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Phase Equilibria and Thermodynamics
- Chemical Thermodynamics and Molecular Structure
- Pulsars and Gravitational Waves Research
- Cold Atom Physics and Bose-Einstein Condensates
- Methane Hydrates and Related Phenomena
- Career Development and Diversity
- Higher Education Research Studies
- Planetary Science and Exploration
- High-pressure geophysics and materials
- Space Exploration and Technology
University of Virginia
2023-2025
Center for Astrophysics Harvard & Smithsonian
2017-2024
Harvard University Press
2017
University of Amsterdam
2009
Planets form and obtain their compositions in dust gas-rich disks around young stars, the outcome of this process is intimately linked to disk chemical properties. The distributions molecules across regulate elemental planets, including C/N/O/S ratios metallicity (O/H C/H), as well access water prebiotically relevant organics. Emission from also encodes information on ionization levels, temperature structures, kinematics, gas surface densities, which are all key ingredients evolution planet...
Here we present high resolution (15-24 au) observations of CO isotopologue lines from the Molecules with ALMA on Planet-forming Scales (MAPS) Large Program. Our analysis employs $^{13}$CO and C$^{18}$O ($J$=2-1), (1-0), C$^{17}$O (1-0) line five protoplanetary disks. We retrieve gas density distributions, using three independent methods: (1) a thermo-chemical modeling framework based data, broadband spectral energy distribution, mm-continuum emission; (2) an empirical temperature...
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 protoplanetary disks around IM Lup, GM Aur, AS 209, HD 163296, MWC 480. By using asymmetry molecular line emission relative disk major axis, we infer height ($z$) above midplane as function radius ($r$). Using this method, measure emitting surfaces for suite CO isotopologues, HCN, C$_2$H. We find that $^{12}$CO traces...
Abstract 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 high angular resolution (0.″15 and 0.″30 beams for Bands 6 3, respectively) sensitivity (spanning 0.3–1.3 mJy beam −1 0.4–1.9 respectively). In this article, we describe multistage workflow—built around CASA tclean image deconvolution procedure—that used to generate core data product MAPS LP:...
The Molecules with ALMA at Planet-forming Scales (MAPS) Large Program provides a detailed, high resolution (${\sim}$10-20 au) view of molecular line emission in five protoplanetary disks spatial scales relevant for planet formation. Here, we present systematic analysis chemical substructures 18 lines toward the MAPS sources: IM Lup, GM Aur, AS 209, HD 163296, and MWC 480. We identify more than 200 substructures, which are found nearly all radii where is detected. A wide diversity radial...
Constraining dust properties of planet-forming disks via high angular resolution observations is fundamental to understanding how solids are trapped in substructures and growth may be favored or accelerated therein. We use ALMA continuum the Molecules with at Planet-forming Scales (MAPS) explore a large parameter space constrain radial distribution solid mass maximum grain size each disk, including excluding scattering. In nonscattering model, surface density profiles decrease from inner...
Abstract We explore the dynamical structure of protoplanetary disks surrounding HD 163296 and MWC 480 as part Molecules with ALMA at Planet-forming Scales (MAPS) large program. Using J = 2–1 transitions 12 CO, 13 C 18 O imaged spatial resolutions ∼0.″15 a channel spacing 200 m s −1 , we find perturbations from Keplerian rotation in projected velocity fields both (≲5% local velocity), suggestive large-scale (tens astronomical units size), coherent flows. By accounting for azimuthal dependence...
Abstract We report the discovery of a circumplanetary disk (CPD) candidate embedded in circumstellar T Tauri star AS 209 at radial distance about 200 au (on-sky separation 1.″4 from position angle 161°), isolated via 13 CO J = 2−1 emission. This is first instance CPD detection gaseous emission capable tracing overall mass. The spatially unresolved with 117 × 82 mas beam and manifests as point source CO, indicating that its diameter ≲14 au. within an annular gap previously identified using 12...
Abstract High spatial resolution CO observations of midinclination (≈30°–75°) protoplanetary disks offer an opportunity to study the vertical distribution emission and temperature. The asymmetry line relative disk major axis allows for a direct mapping height above midplane, optically thick, spatially resolved in LTE, intensity is measure local gas Our analysis Atacama Large Millimeter/submillimeter Array archival data yields surfaces, dynamically constrained stellar host masses, atmosphere...
Abstract The Atacama Large Millimeter/submillimeter Array (ALMA) can probe the molecular content of planet-forming disks with unprecedented sensitivity. These observations allow us to build up an inventory volatiles available for forming planets and comets. Herbig Ae transition are fruitful targets due thermal sublimation complex organic molecules (COMs) likely H 2 O-rich ices in these disks. IRS 48 disk shows a particularly rich chemistry that be directly linked its asymmetric dust trap....
Abstract Observations of disks with the Atacama Large Millimeter/submillimeter Array (ALMA) allow us to map chemical makeup nearby protoplanetary unprecedented spatial resolution and sensitivity. The typical outer Class II disk observed ALMA is one an elevated C/O ratio a lack oxygen-bearing complex organic molecules, but there are now some interesting exceptions: three transition around Herbig Ae stars all show oxygen-rich gas traced via unique detections molecules SO CH 3 OH. We present...
Abstract We present MIRI Medium-resolution Spectrograph observations of the large, multi-gapped protoplanetary disk around T Tauri star AS 209. The reveal hundreds water vapor lines from 4.9–25.5 μ m toward inner ∼1 au in disk, including first detection rovibrational emission this disk. spectrum is dominated by hot (∼800 K) and OH gas, with only marginal detections CO 2 , HCN, a possible colder component. Using slab models detailed treatment opacities line overlap, we retrieve column...
Abstract PDS 70 hosts two massive, still-accreting planets and the inclined orientation of its protoplanetary disk presents a unique opportunity to directly probe vertical gas structure planet-hosting disk. Here, we use high-spatial-resolution (≈0.″1; 10 au) observations in set CO isotopologue lines HCO + J = 4−3 map full 2D ( r , z ) from atmosphere, as traced by 12 CO, closer midplane, probed less abundant isotopologues . In disk, traces height / ≈ 0.3, 13 is found at 0.1, C 18 O...
The elemental composition of the gas and dust in a protoplanetary disk influences compositions planets that form it. We use Molecules with ALMA at Planet-forming Scales (MAPS) data to constrain locations potentially forming planets. abundances are inferred by comparing source-specific gas-grain thermochemical models, variable C/O ratios small-grain abundances, from DALI code CO C2H column densities derived high-resolution observations disks AS 209, HD 163296, MWC 480. Elevated (~2.0), even...
Small organic molecules, such as C2H, HCN, and H2CO, are tracers of the C, N, O budget in protoplanetary disks. We present high angular resolution (10-50 au) observations H2CO lines five disks from Molecules with ALMA at Planet-forming Scales (MAPS) Large Program. derive column density excitation temperature profiles for HCN find that emission arises a temperate (20-30 K) layer disk, while C2H is relatively warmer (20-60 layers. In case HD 163296, we decrease inside one dust gaps near 83 au,...
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, grain processing. Commonly detected diverse astrophysical objects, including the Solar System, their distribution remain, however, largely unknown planet-forming disks. We present CS ($2-1$) observations at $\sim0."3$ resolution performed within ALMA-MAPS Large Program toward five disks around IM Lup, GM Aur, AS 209, HD 163296,...
The precursors to larger, biologically-relevant molecules are detected throughout interstellar space, but determining the presence and properties of these during planet formation requires observations protoplanetary disks at high angular resolution sensitivity. Here we present 0.3" HC$_3$N, CH$_3$CN, $c$-C$_3$H$_2$ in five observed as part Molecules with ALMA Planet-forming Scales (MAPS) Large Program. We robustly detect all four (GM Aur, AS 209, HD 163296 MWC 480) tentative detections...
Abstract The concentric gaps and rings commonly observed in protoplanetary disks millimeter continuum emission have lent the impression that planet formation generally proceeds within orderly, isolated systems. While deep observations of spatially resolved molecular been comparatively limited, they are increasingly suggesting some interact with their surroundings while is underway. We present an analysis complex features identified around GM Aur 12 CO J = 2 − 1 images at a spatial resolution...
Abstract High-spatial-resolution observations of CO isotopologue line emission in protoplanetary disks at mid-inclinations (≈30°–75°) allow us to characterize the gas structure detail, including radial and vertical substructures, surface heights their dependencies on source characteristics, disk temperature profiles. By combining a suite isotopologues, we can map two-dimensional ( r , z ) from upper atmosphere, as traced by CO, near midplane, probed less abundant isotopologues. Here, present...
Abstract Planets form in dusty, gas-rich disks around young stars, while at the same time, planet formation process alters physical and chemical structure of disk itself. Embedded planets will locally heat sublimate volatile-rich ices, or extreme cases, result shocks that sputter heavy atoms such as Si from dust grains. This should cause asymmetries detectable molecular gas observations. Using high-angular-resolution ALMA archival data HD 169142 disk, we identify compact SO J = 8 − 7 SiS 19...
The composition of a forming planet is set by the material it accretes from its parent protoplanetary disk. Therefore, crucial to map chemical make-up gas in disks understand environment formation. This paper presents molecular line observations taken with Atacama Large Millimeter/submillimeter Array planet-hosting disk around young star HD 169142. We detect N 2 H + , CH 3 OH, [CI], DCN, CS, C 34 S, 13 CO, HC N, and c–C this system for first time. Combining these data recent detection SO...
Abstract We observed HCO + J = 1 − 0 and H 13 CO emission toward the five protoplanetary disks around IM Lup, GM Aur, AS 209, HD 163296, MWC 480 as part of MAPS project. is detected mapped at 0.″3 resolution in all disks, while (S/N > 6 σ ) Aur 163296 tentatively 3 other by a matched filter analysis. Inside radius R ∼ 100 au, column density flat or shows central dip. At outer radii (≳100 au), decreases outward, ratio /CO mostly range ∼10 −5 –10 −4 . derived abundance warm CO-rich layer,...
UV photochemistry in the surface layers of protoplanetary disks dramatically alters their composition relative to previous stages star formation. The abundance ratio CN/HCN has long been proposed trace field various astrophysical objects, however date relationship between CN, HCN, and remains ambiguous. As part ALMA Large Program MAPS (Molecules with at Planet-forming Scales), we present observations CN N=1-0 transitions 0.3'' resolution towards five disk systems. All show bright emission...
Abstract Gas mass remains one of the most difficult protoplanetary disk properties to constrain. With much too cold for main gas constituent, H 2 , emit, alternative tracers such as dust, CO, or isotopologue HD are used. However, relying on measurements from any single tracer requires assumptions about tracer’s abundance relative and temperature structure. Using new Atacama Large Millimeter/submillimeter Array (ALMA) observations Molecules with ALMA at Planet-forming Scales (MAPS) Program...
We study the kinematics of AS 209 disk using J=2-1 transitions $^{12}$CO, $^{13}$CO, and C$^{18}$O. derive radial, azimuthal, vertical velocity gas, taking into account lowered emission surface near annular gap at ~1.7 (200 au) within which a candidate circumplanetary disk-hosting planet has been reported previously. In $^{12}$CO we find coherent upward flow arising from gap. The gas is as fast $150~{\rm m~s}^{-1}$ in regions traced by emission, corresponds to about 50% local sound speed or...