A5081820942- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Molecular Spectroscopy and Structure
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- Astrophysical Phenomena and Observations
- Solar and Space Plasma Dynamics
- Spectroscopy and Laser Applications
- Astronomy and Astrophysical Research
- Fluid Dynamics Simulations and Interactions
- Spacecraft and Cryogenic Technologies
- Advanced Combustion Engine Technologies
- Atomic and Molecular Physics
- Phase Equilibria and Thermodynamics
- Fluid Dynamics and Turbulent Flows
Imperial College London
2023-2025
Queen Mary University of London
2020-2024
University of Leicester
2018-2021
We present Phantom, a fast, parallel, modular and low-memory smoothed particle hydrodynamics magnetohydrodynamics code developed over the last decade for astrophysical applications in three dimensions. The has been with focus on stellar, galactic, planetary high energy astrophysics already used widely studies of accretion discs turbulence, from birth planets to how black holes accrete. Here we describe test core algorithms as well modules magnetohydrodynamics, self-gravity, sink particles,...
Abstract Understanding when and how circumstellar disks disperse is crucial to constrain planet formation migration. Thermal winds powered by high-energy stellar photons have long been theorized drive disk dispersal. However, evidence for these currently based only on small (∼3–6 km s −1 ) blueshifts in [Ne ii ] 12.81 μ m lines, which does not exclude MHD winds. We report JWST MIRI MRS spectro-imaging of T Cha, a with large dust gap (∼30 au radius) blueshifted emission. detect four forbidden...
Abstract [Ne ii ] 12.81 μ m emission is a well-used tracer of protoplanetary disk winds due to its blueshifted line profile. Mid-Infrared Instrument (MIRI)-Medium Resolution Spectrometer (MRS) recently observed T Cha, detecting this along with lines iii ], [Ar and the found be extended while was not. In complementary work, we use these address long-debated questions about regarding their mass-loss rate, origin ionization, role magnetically driven as opposed photoevaporation. To end, perform...
Atmospheric escape is now considered the major contributing factor in shaping demographic of detected exoplanets. However, inferences about exoplanet populations strongly depend on accuracy models. Direct observational tests atmospheric models are still their infancy. Helium from planetary atmospheres has rapidly become primary probe, already observed $\gtrsim$20 Grounding our understanding basic physics escape, we present a new theoretical model to predict excess absorption helium line. We...
Abstract Atmospheric escape is now considered the major contributing factor in shaping demographic of detected exoplanets. However, inferences about exoplanet populations strongly depend on accuracy models. Direct observational tests atmospheric models are still their infancy. Helium from planetary atmospheres has rapidly become primary probe, already observed ≳20 Grounding our understanding basic physics escape, we present a new theoretical model to predict excess absorption helium line. We...
Recent years have seen a surge of interest in the community studying effect ultraviolet radiation environment, predominantly set by OB stars, on protoplanetary disc evolution and planet formation. This is important because significant fraction planetary systems, potentially including our own, formed close proximity to stars. rapidly developing field, with broad range observations across many regions recently obtained or scheduled. In this paper, stimulated series workshops topic, we take...
A recent survey of the inner $0.35\times0.35$pc NGC 2024 star forming region revealed two distinct millimetre continuum disc populations that appear to be spatially segregated by boundary a dense cloud. The eastern (and more embedded) population is $\sim0.2-0.5$Myr old, with an ALMA mm detection rate about $45\,$per cent. However this drops only $\sim15$per cent in 1Myr western population. When presenting result, van Terwisga et al. (2020) suggested main UV sources, IRS 1 (a B0.5V region)...
We describe a new implementation of the one-fluid method in SPH code Phantom to simulate dynamics dust grains gas protoplanetary discs. revise and extend previously developed algorithms by computing evolution fluid quantity that produces more accurate numerically controlled dynamics. Moreover, limiting stopping time uncoupled violate assumptions terminal velocity approximation, we avoid fatal numerical errors mass conservation. test validate our algorithm running 3D simulations large range...
ABSTRACT Photoevaporation driven by high-energy radiation from the central star plays an important role in evolution of protoplanetary discs. Photoevaporative winds have been unambiguously detected through blue-shifted emission lines, but their detailed properties remain uncertain. Here we present a new empirical approach to make observational predictions these thermal winds, seeking fill gap between theory and observations. We use self-similar model isothermal wind compute line profiles...
Misalignments within protoplanetary discs are now commonly observed, and features such as shadows in scattered light images indicate departure from a co-planar geometry. VLT/SPHERE observations of the disc around HD 143006 show large-scale asymmetry, two narrow dark lanes which indicative shadowing. ALMA also reveal presence rings gaps disc, along with bright arc at large radii. We present new hydrodynamic simulations 143006, that configuration both strongly inclined binary an outer...
ABSTRACT We present Very Large Telescope/Multi-Unit Spectroscopic Explorer Narrow Field Mode observations of a pair disc-bearing young stellar objects towards the Orion Bar: 203–504 and 203–506. Both these discs are subject to external photoevaporation, where winds launched from their outer regions due environmental irradiation. Intriguingly, despite having projected separation one another only 1.65 arcsec(660 au at 400 pc), has classic teardrop shaped ‘proplyd’ morphology pointing θ2 Ori A...
We study the utility of [OI] 6300$\mathring{\mathrm A}$ forbidden line for identifying and interpreting externally driven photoevaporative winds in different environments at a range distances. Thermally excited is well known tracer inner disc winds, so any external contribution needs to be distinguishable. In not thermally instead results from dissociation OH we how luminosity resulting that process scales with disc/environmental parameters. find increases dramatically FUV radiation field...
Abstract We analyze high-resolution (Δ v ≤ 10 km s −1 ) optical and infrared spectra covering the [O i ] λ 6300 [Ne ii 12.81 μ m lines from a sample of 31 disks in different evolutionary stages. Following work at wavelengths, we use Gaussian profiles to fit classify them into high-velocity component (HVC) or low-velocity (LVC) if line centroid is more less blueshifted than 30 with respect stellar radial velocity, respectively. Unlike for ], where an HVC often accompanied by LVC, all 17...
We used the Atacama Pathfinder Experiment (APEX) telescope to search for CI 1-0 (492.16GHz) emission towards 8 proplyds in NGC 1977, which is an FUV radiation environment two orders of magnitude weaker than that irradiating Orion Nebular Cluster (ONC) proplyds. expected enable us probe wind launching region externally photoevaporating discs. Of targets observed, no 3$\sigma$ detections line were made despite reaching sensitivities deeper anticipated requirement detection from prior APEX...
Understanding when and how circumstellar disks disperse is crucial to constrain planet formation migration. Thermal winds powered by high-energy stellar photons have long been theorized drive disk dispersal. However, evidence for these currently based only on small (~3-6 km/s) blue-shifts in [Ne II] 12.81 um lines, which does not exclude MHD winds. We report JWST MIRI MRS spectro-imaging of T Cha, a with large dust gap (~30 au radius) blue-shifted emission. detect four forbidden noble gas...
[Ne II] 12.81 $\mu\mathrm{m}$ emission is a well-used tracer of protoplanetary disk winds due to its blueshifted line profile. MIRI-MRS recently observed T Cha, detecting this along with lines III], [Ar and the III] found be extended while was not. In complementary work, we use these address long-debated questions about regarding their mass-loss rate, origin ionization, role magnetically-driven as opposed photoevaporation. To end, perform photoionization radiative transfer on simple...
We present JWST/MIRI observations of T~Cha, a highly variable ($\Delta V \sim$3-5\,mag) accreting Sun-like star surrounded by disk with large ($\sim 15$\,au) dust gap. find that the JWST mid-infrared spectrum is signiticantly different from {\it Spitzer} obtained 17 years before, where emission at short wavelengths ($5-10 \mu m$) has decreased $\sim 2/3$ while longer ($15-25 it increased up to factor 3$. This 'seesaw' behavior contemporary fairly constant higher optical captured All Sky...
The evolution of protoplanetary disks in regions with massive OB stars is influenced by externally driven winds that deplete the outer parts these disks. have previously been studied via forbidden oxygen emission lines, which also arise isolated low-mass star-forming (SFRs) weak external UV fields photoevaporative or magnetic (internal) disk winds. It crucial to determine how disentangle from internal ones. Here, we report a proxy for unambiguously identifying line neutral atomic carbon We...
The evolution of protoplanetary disks in regions with massive OB stars is influenced by externally driven winds that deplete the outer parts disks. These have previously been studied via forbidden oxygen emission lines, which also arise isolated low-mass star forming-regions (SFRs) weak external UV fields photoevaporative or magnetic (internal) disk winds. It crucial to determine how disentangle from internal ones. Here, we report a proxy for unambiguously identifying line neutral atomic...
Disk winds play a crucial role in the evolution of protoplanetary disks. Typical conditions for star and planet formation are regions with intermediate or strong UV radiation fields produced by massive stars. In these environments, internally externally driven can occur. The is ideal site to study disk under conditions; its outer parts, exposed only mild fields, be used evolution, while innermost effect external irradiation. Our goal looking at properties optical forbidden lines, comparing...
Disk winds play a crucial role in the evolution of protoplanetary disks. Typical conditions for star and planet formation are regions with intermediate or strong UV radiation fields produced by massive stars. The $\sigma$-Orionis cluster is ideal site to study disk under these conditions; its outer parts can be used evolution, while innermost effect external irradiation. For this, we analyze $\rm [OI]\,\lambda$6300, [NII]\,\lambda$6583, [SII]\,\lambda$6731,$\lambda$6716 lines using...
Abstract We analyze JWST/MIRI observations of T Cha, a highly variable (Δ V ∼ 3–5 mag) accreting Sun-like star surrounded by disk with large (∼15 au) dust gap. find that the JWST mid-IR spectrum is significantly different from Spitzer obtained 17 yr before—the emission at short wavelengths (5–10 μ m) has decreased ∼2/3 while longer (15–25 increased up to factor ∼3. The contemporaneous fairly constant higher optical captured All Sky Automated Survey. After analyzing and modeling both spectral...
We present VLT/MUSE Narrow Field Mode (NFM) observations of a pair disc-bearing young stellar objects towards the Orion Bar: 203-504 and 203-506. Both these discs are subject to external photoevaporation, where winds launched from their outer regions due environmental irradiation. Intriguingly, despite having projected separation one another only 1.65{\arcsec} (660au at 400pc), has classic teardrop shaped ``proplyd'' morphology pointing $\theta^2$Ori A (indicating irradiation by EUV that...