A5046128744- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Geophysics and Gravity Measurements
- Geomagnetism and Paleomagnetism Studies
- Planetary Science and Exploration
- Solar Radiation and Photovoltaics
- Atmospheric Ozone and Climate
- Electric and Hybrid Vehicle Technologies
- Particle Accelerators and Free-Electron Lasers
- Real-time simulation and control systems
- Geological and Geophysical Studies
- Hydraulic and Pneumatic Systems
- Drilling and Well Engineering
- Reservoir Engineering and Simulation Methods
- Superconducting Materials and Applications
- Optical measurement and interference techniques
- Spacecraft and Cryogenic Technologies
- Gamma-ray bursts and supernovae
- Infrared Target Detection Methodologies
- Calibration and Measurement Techniques
- solar cell performance optimization
KU Leuven
2020-2024
Ames Research Center
2010-2022
University College London
2018-2020
Search for Extraterrestrial Intelligence
2010
Weatherford (Switzerland)
2005
Petroleum of Venezuela (Venezuela)
2002
We have studied solar-like oscillations in ~800 red-giant stars using Kepler long-cadence photometry. The sample includes ranging evolution from the lower part of branch to Helium main sequence. investigate relation between large frequency separation (Delta nu) and maximum power (nu_max) show that it is different for red giants than main-sequence stars, which consistent with evolutionary models scaling relations. distributions nu_max Delta nu are qualitative agreement a simple stellar...
Solar Orbiter is the first space mission observing solar plasma both in situ and remotely, from a close distance, out of ecliptic. The ultimate goal to understand how Sun produces controls heliosphere, filling System driving planetary environments. With six remote-sensing four in-situ instrument suites, coordination planning operations are essential address following top-level science questions: (1) What drives wind where does coronal magnetic field originate? (2) How do transients drive...
L 98-59 (TIC 307210830, TOI-175) is a nearby M3 dwarf around which TESS revealed three terrestrial-sized transiting planets (0.80, 1.35, 1.57 Earth radii) in compact configuration with orbital periods shorter than 7.5 days. Here we aim to measure the masses of known this system using precise radial velocity (RV) measurements taken HARPS spectrograph. We consider both trained and untrained Gaussian process regression models stellar activity simultaneously model RV data planetary signals. Our...
Context. Prominences and coronal rain are two forms of condensations for which we still lack satisfactory details on the formation pathways conditions under come to exist. Even more so, it is unclear why prominences filaments appear in so many different shapes sizes, with a vertical rather than horizontal structure or vice-versa. It also not clear present some cases others. Aims. Our aim understand process detail by exploring what influence specific heating prescriptions can have resulting...
We present the confirmation and characterisation of GJ 3473 b (G 50--16, TOI-488.01), a hot Earth-sized planet orbiting an M4 dwarf star, whose transiting signal ($P=1.1980035\pm0.0000018\mathrm{\,d}$) was first detected by Transiting Exoplanet Survey Satellite (TESS). Through joint modelling follow-up radial velocity observations with CARMENES, IRD, HARPS together extensive ground-based photometric LCOGT, MuSCAT, MuSCAT2, we determined precise planetary mass, $M_b =...
Prominences in the solar atmosphere represent an intriguing and delicate balance of forces thermodynamics evolving magnetic topology. How this relatively cool material comes to reside at coronal heights, what drives its evolution prior to, during, after appearance remains area full open questions. We deliberately focus on levitation-condensation scenario, where a flux rope forms eventually demonstrates in-situ condensations, revisiting it extreme resolutions down order 6 km scale. perform...
We describe a partial filament eruption on 11 December 2011 which demonstrates that the inclusion of mass is an important next step for understanding solar eruptions. Observations from \textit{Solar Terrestrial Relations Observatory Behind} (STEREO-B) and Dynamics Observatory} (SDO) spacecraft were used to remove line-of-sight projection effects in motion correlate effect plasma dynamics with evolution height. Flux cancellation nearby flux emergence are shown have played role increasing...
Abstract Solar prominences observed close to the limb commonly include a bright feature that, from perspective of observer, runs along interface between itself and underlying chromosphere. Despite several idealized models being proposed explain physics, more general approach remains outstanding. In this manuscript we demonstrate as proof concept first steps in applying Lightweaver radiative transfer framework’s 2.5D extension “toy” model prominence + VAL3C chromosphere, inspired by recent...
Abstract Quiescent solar prominences are observed within the atmosphere for up to several rotations. Their eruption is commonly preceded by a slow increase in height that can last from hours days. This prominence believed be due their host magnetic flux rope transitioning through series of neighboring quasi-equilibria before main loss equilibrium drives eruption. Recent work suggests removal mass stable, quiescent one possible cause this change height. However, these conclusions drawn...
Aims. We begin by exploring the influence of two classes commonly adopted heating models on formation behaviour solar prominences. These consider either an exponential variation dependent height alone, or local density and magnetic field conditions. highlight address some limitations inherent to these early approximations proposing a new, dynamic 2D flux rope model that qualitatively accounts for 3D topology twisted field. Methods. performed 2.5D grid-adaptive numerical simulations...
Abstract Coronal cavities have previously been observed to be associated with long-lived quiescent filaments and are thought correspond the magnetic flux rope. Although standard flare model predicts a coronal cavity corresponding erupting rope, these only using broadband imaging data, restricting an analysis plane-of-sky. We present unique set of spectroscopic observations active region filament seen at solar limb in extreme ultraviolet. The erupted expanded rapidly, change rise phase...
We report the discovery of TOI-1268b, a transiting Saturn-mass planet from TESS space mission. With an age less than one Gyr, derived various indicators, TOI-1268b is youngest known to date and contributes small sample well characterised young planets. It has orbital period $P\,=\,8.1577080\pm0.0000044$ days, transits early K dwarf star with mass $M_\star$ = $ 0.96 \pm 0.04$ $M_{\odot}$, radius $R_\star$ 0.92 0.06$ $R_{\odot}$, effective temperature $T_\mathrm{eff}\,=\,5300\pm100$ K,...
Aims. We here demonstrate how the recently developed Lightweaver framework makes non-LTE (NLTE) spectral synthesis feasible on a new 3D ab-initio magnetohydrodynamic (MHD) filament/prominence simulation, in post-processing step. Methods. clarify need to introduce filament/prominent-specific boundary conditions that accurately model incident chromospheric radiation, and include self-consistent smoothly varying limb darkening function. Results. Progressing from isothermal/isobaric models...
Context. The tearing instability plays a major role in the disruption of current sheets, whereas thermal modes can be responsible for condensation phenomena (forming prominences and coronal rain) solar atmosphere. However, how sheets made unstable by combined evolve within atmosphere has received limited attention to date. Aims. We numerically explore that causes break up an idealized sheet component leads formation localized, cool condensations otherwise 3D reconnecting magnetic topology....
Abstract Freely propagating global waves in the solar atmosphere are commonly observed using extreme ultraviolet passbands (EUV or “EIT waves”), and less regularly H-alpha (Moreton–Ramsey waves). Despite decades of research, joint observations EUV Moreton–Ramsey remain rare, complicating efforts to quantify connection between these phenomena. We present four homologous originating from same active region 2014 March 28 30 both data. Each wave was by Solar Dynamics Observatory , with...
Aims. Accurately and rapidly classifying exoplanet candidates from transit surveys is a goal of growing importance as the data rates space-based survey missions increase. This especially true for NASA TESS mission which generates thousands new each month. Here we created first deep-learning model capable planet candidates. Methods. We adapted an existing neural network then trained tested this updated on four sectors high-fidelity, pixel-level simulations using Lilith simulator processed...
Context. We study a fragment of large quiescent filament observed on May 29, 2017 by the Interferometric BIdimensional Spectropolarimeter (IBIS) mounted at Dunn Solar Telescope. focus its stage prior to eruption. Aims. analyse spectral observations obtained in H α line derive thermodynamic properties plasma filament. Methods. used 2D model employing radiative transfer computations under conditions that depart from local equilibrium. employed forward modelling technique which we produce...
Abstract The full 3D vector magnetic field of a solar filament prior to eruption is presented. was observed with the Facility Infrared Spectropolarimeter at Dunn Solar Telescope in chromospheric He i line 10830 Å on 2017 May 29 and 30. We inverted spectropolarimetric observations Hanle Zeeman Light code obtain field. A bimodal distribution strength found or near filament. average 24 Gauss, but we find 90th percentile 435 Gauss for 29. inclination about 67° from vertical. azimuth made an...
WASP-148 is a recently announced extra-solar system harbouring at least two giant planets. The inner planet transits its host star. planets travel on eccentric orbits and are near the 4:1 mean-motion resonance, which implies significant mutual gravitational interactions. In particular, this causes transit-timing variations of few minutes, were detected based ground-based photometry. This made one cases where such phenomenon was without space-based Here, we present self-consistent model that...
Solar prominences represent large-scale condensations suspended against gravity within the solar atmosphere. The Rayleigh-Taylor (RT) instability is proposed to be one of important fundamental processes leading generation dynamics at many spatial and temporal scales these long-lived, cool, dense structures amongst corona. We run 2.5D ideal magnetohydrodynamic (MHD) simulations with open-source MPI-AMRVAC code far into nonlinear evolution an RT perturbed prominence-corona interface. Our...
Abstract Pressured Mud Cap Drilling (PMCD) is an advanced technique to control wells which encounter heavy mud losses and has been applied on onshore offshore with surface wellheads. The key successfully apply the use of a Rotating Control Device (RCD), technology taken from Under Balanced (UBD). PMCD not date subsea as rigging up RCD drilling riser brings additional challenges compared wells. Three were drilled Offshore Sarawak, utilizing technique. A detailed review was made rig...
Abstract Solar filaments exist as stable structures for extended periods of time before many them form the core a coronal mass ejection (CME). We examine properties an erupting filament on 2017 May 29–30 with high-resolution He i 10830 Å and H α spectra from Dunn Telescope, full-disk Dopplergrams Chromospheric EUV coronograph data SDO STEREO. Pre-eruption line-of-sight velocities inversion HAZEL code exhibit coherent patches 5 Mm extent that indicate counter-streaming and/or buoyant...