Romane Le Gal
A5000988859- Astrophysics and Star Formation Studies
- Molecular Spectroscopy and Structure
- Atmospheric Ozone and Climate
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Advanced Chemical Physics Studies
- Spectroscopy and Laser Applications
- Atmospheric chemistry and aerosols
- Solar and Space Plasma Dynamics
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Nuclear physics research studies
- Spacecraft and Cryogenic Technologies
- Atomic and Molecular Physics
- SAS software applications and methods
- Inorganic Fluorides and Related Compounds
- Thermodynamic properties of mixtures
- Nuclear Physics and Applications
- Phase Equilibria and Thermodynamics
- Structural and Chemical Analysis of Organic and Inorganic Compounds
- Radioactive Decay and Measurement Techniques
- 2D Materials and Applications
- Nuclear reactor physics and engineering
- Geophysics and Gravity Measurements
- Zeolite Catalysis and Synthesis
Institut de Planétologie et d'Astrophysique de Grenoble
2013-2024
Institut de Radioastronomie Millimétrique
2022-2024
Centre National de la Recherche Scientifique
2013-2024
Université Grenoble Alpes
2013-2024
Université de Toulouse
2021-2024
Institut de Recherche en Astrophysique et Planétologie
2021-2024
Centre National d'Études Spatiales
2024
Center for Astrophysics Harvard & Smithsonian
2017-2023
Ausonius Institut de Recherche sur l'Antiquité et le Moyen age
2021-2023
Université Toulouse III - Paul Sabatier
2021-2022
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...
Context . JWST has taken the sharpest and most sensitive infrared (IR) spectral imaging observations ever of Orion Bar photodis-sociation region (PDR), which is part nearest massive star-forming Nebula, often considered to be ‘prototypical’ strongly illuminated PDR. Aims We investigate impact radiative feedback from stars on their natal cloud focus transition H II atomic PDR – crossing ionisation front (IF) –, subsequent molecular dissociation (DF). Given prevalence PDRs in interstellar...
The L1544 pre-stellar core has been observed as part of the ASAI IRAM 30 m Large Program well follow-up programs. These observations have revealed chemical richness earliest phases low-mass star-forming regions. In this paper, we focus on 21 sulphur bearing species (ions, isotopomers, and deuteration) that detected in spectral-survey through 51 transitions: CS, CCS, C3S, SO, SO2, H2CS, OCS, HSCN, NS, HCS+, NS+, H2S. We also report tentative detection (4σ level) for methyl mercaptan (CH3SH)....
The aim of the present work is to perform a comprehensive analysis interstellar chemistry nitrogen, focussing on gas-phase formation smallest polyatomic species and in particular nitrogen hydrides. We new chemical network which kinetic rates critical reactions have been updated based recent experimental theoretical studies, including nuclear spin branching ratios. Our thus treats different symmetries hydrides self-consistently together with ortho para forms molecular hydrogen. This used...
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 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...
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...
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...
Abstract Massive stars disrupt their natal molecular cloud material through radiative and mechanical feedback processes. These processes have profound effects on the evolution of interstellar matter in our Galaxy throughout universe, from era vigorous star formation at redshifts 1–3 to present day. The dominant can be probed by observations Photo-Dissociation Regions (PDRs) where far-ultraviolet photons massive create warm regions gas dust neutral atomic gas. PDR emission provides a unique...
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...
(Abridged) Mid-infrared observations of photodissociation regions (PDRs) are dominated by strong emission features called aromatic infrared bands (AIBs). The most prominent AIBs found at 3.3, 6.2, 7.7, 8.6, and 11.2 $\mu$m. sensitive, highest-resolution spectral imaging data ever taken the prototypical PDR, Orion Bar, have been captured JWST. We provide an inventory in along with mid-IR template spectra from five distinct Bar: molecular atomic HII region. use JWST NIRSpec IFU MIRI MRS Bar...
Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict this FUV radiation produces photodissociation regions (PDRs) on the surfaces protoplanetary disks around affects planet formation within disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations a FUV-irradiated disk Orion Nebula. Emission lines detected from PDR; modeling their kinematics excitation...
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 We present the first detection of gas-phase S 2 H in Horsehead, a moderately UV-irradiated nebula. This confirms presence doubly sulfuretted species interstellar medium and opens new challenge for sulfur chemistry. The observed abundance is ∼5 × 10 −11 , only factor 4–6 lower than that widespread molecule. are efficiently formed on icy grain mantles. performed ice irradiation experiments to determine photodesorption yields. obtained values ∼1.2 −3 <1 −5 molecules per incident...
Abstract H 2 CO is one of the most abundant organic molecules in protoplanetary disks and can serve as a precursor to more complex chemistry. We present an Atacama Large Millimeter/submillimeter Array survey toward 15 covering range stellar spectral types, ages, dust continuum morphologies. detected 13 tentatively fourteenth. find both centrally peaked depressed emission morphologies, half show ring-like structures at or beyond expected snowline locations. Together these morphologies suggest...
Sulphur is one of the most abundant elements in Universe. Surprisingly, sulphuretted molecules are not as expected interstellar medium, and identity main sulphur reservoir still an open question. Our goal to investigate H$_{2}$S chemistry dark clouds, this stable molecule a potential reservoir. Using millimeter observations CS, SO, H$_{2}$S, their isotopologues, we determine physical conditions abundances along cores TMC 1-C, 1-CP, Barnard 1b. The gas-grain model Nautilus then used explore...
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,...
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...
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...