A5080103143- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Solar and Space Plasma Dynamics
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Historical Astronomy and Related Studies
- Numerical methods for differential equations
- Space Exploration and Technology
- Cryospheric studies and observations
- AI-based Problem Solving and Planning
- Control and Stability of Dynamical Systems
- Geophysics and Gravity Measurements
- Arctic and Antarctic ice dynamics
- Dynamics and Control of Mechanical Systems
- Robot Manipulation and Learning
Leiden University
2023-2025
University of Southern Queensland
2018-2024
Leiden Observatory
2024
Science and Technology Corporation (Norway)
2016
We report the discovery of a warm sub-Saturn, TOI-257b (HD 19916b), based on data from NASA's Transiting Exoplanet Survey Satellite (TESS). The transit signal was detected by TESS and confirmed to be planetary origin radial velocity observations. An analysis photometry, Minerva-Australis, FEROS, HARPS velocities, asteroseismic stellar oscillations reveals that has mass $M_P=0.138\pm0.023$\,$\rm{M_J}$ ($43.9\pm7.3$\,$M_{\rm \oplus}$), radius $R_P=0.639\pm0.013$\,$\rm{R_J}$...
Understanding atmospheric escape over geological timescales is essential for constraining a planet's capacity to retain its atmosphere and sustain life. Earth’s has drastically changed in composition, with significant increase oxygen occurring during the Great Oxidation Event (GOE) 2.45 Gyr ago. Atmospheric can be ionized energized by solar radiation plasma interactions involving wind, magnetosphere, ionosphere, eventually leading into space either as neutral or an O+...
ABSTRACT Solar-type stars, which shed angular momentum via magnetized stellar winds, enter the main sequence with a wide range of rotational periods Prot. This initially contracts and has mostly vanished by age $t\sim {0.6}\, {\rm Gyr}$, after stars spin according to Skumanich relation $P_\text{rot}\propto \sqrt{t}$. Magnetohydrodynamic wind models can improve our understanding this convergence rotation periods. We present 15 young aged ∼24 Myr ∼0.13 Gyr. With previous ∼0.26 ∼0.6 Gyr we...
Context. The accurate characterisation of the stellar magnetism planetary host stars has been gaining momentum, especially in context transmission spectroscopy investigations exoplanets. Indeed, magnetic field regulates amount energetic radiation and wind impinging on planets, as well presence inhomogeneities surface that hinder precise extraction atmospheric absorption signal. Aims. We initiated a spectropolarimetric campaign to unveil properties known exoplanet hosting included current...
ABSTRACT AB Dor is a young solar-type star with surface large-scale magnetic field $10^2$ to $10^3$ times stronger than the that of Sun. Although strong fields are thought inhibit coronal mass ejections (CMEs), dimming signatures typically associated an eruptive CME were recently observed in Dor. The uninterrupted, long-duration signal suggests took place at high latitude, where it remained view as rotates. A high-latitude also consistent observations indicate hosts polar active regions. To...
ABSTRACT Stellar winds govern the spin-down of Solar-type stars as they age, and play an important role in determining planetary habitability, powerful can lead to atmospheric erosion. We calculate 3D stellar wind models for five young Hyades cluster, using TOUPIES survey magnetograms state-of-the-art Alfvén wave-driven modelling. The have same 0.6 Gyr age similar fundamental parameters, we account uncertainty underestimation absolute field strength inherent Zeeman–Doppler imaging by...
We have observed the active star $\xi$ Boo A (HD 131156A) with high precision broadband linear polarimetry contemporaneously circular spectropolarimetry. find both signals are modulated by 6.43 day rotation period of A. The from two techniques 0.25 out phase, consistent polarization resulting differential saturation spectral lines in global transverse magnetic field. mean magnitude signal is ~4 ppm/G but its structure complex and amplitude variations suppressed relative to longitudinal...
We present high-precision linear polarization observations of four bright hot Jupiter systems ($τ$ Boo, HD 179949, 189733 and 51 Peg) use the data to search for polarized reflected light from planets. The Peg are consistent with a signal at about level expected 2.8$σ$ significance false alarm probability 1.9 per cent. More will be needed confirm detection in this system. shows highly variable that appears most likely result magnetic activity host star. This masks any due light, but $\sim$20...
ABSTRACT We present wind models of 10 young Solar-type stars in the Hercules-Lyra association and Coma Berenices cluster aged around ∼0.26 ∼0.58 Gyr, respectively. Combined with five previously modelled Hyades cluster, ∼0.63 we obtain a large atlas 15 observationally based models. find varied geometries, multi-armed structures equatorial plane, greater spread quantities such as angular momentum loss. In our models, infer variation factor ∼6 loss $\dot{J}$ ∼2 mass-loss $\dot{M}$ on magnetic...
ABSTRACT F stars lie in the transition region between cool with dynamo generated fields and hot star fossil offer an interesting window into generation of magnetic shallow convection zones. In this paper, we investigate field mature F7V primary bright χ Draconis system. Dra was observed circularly polarized light at four epochs from 2014 through to 2019 using NARVAL spectropolarimeter Téléscope Bernard Lyot. Using technique least-squares deconvolution, created high signal-to-noise line...
The accurate characterisation of the stellar magnetism planetary host stars has been gaining momentum, especially in context transmission spectroscopy investigations exoplanets. Indeed, magnetic field regulates amount energetic radiation and wind impinging on planets, as well presence inhomogeneities surface that hinder precise extraction atmospheric absorption signal. We initiated a spectropolarimetric campaign to unveil properties known exoplanet hosting included current list potential...
ABSTRACT Mapping the large-scale magnetic field in late F-type stars is important for understanding nature of stellar dynamo and dynamics thin outer convection zones. We use Zeeman Doppler Imaging to produce multi-epoch maps surface two mature stars: β Virginis (F9V) θ Draconis (F8IV). also provide a magnetohydrodynamic model winds from corona inner astrosphere, which exists an environment at hot end habitability exoplanets. Our results show that either simple or complex fields are present...
The recent past has seen robots develop into autonomous artificial agents capable of executing complex tasks. In the near future, will likely ability to adapt and learn from their surroundings. Robots have self-reliance, accuracy, can operate in hostile environments - all attributes well suited for space exploration. also reduce mission costs, increase design flexibility, maximize data production. On other hand, when faced with new scenarios unexpected events, pale comparison intuitive...
AB Dor is a young solar-type star with surface large-scale magnetic field $10^2$ to $10^3$ times stronger than the that of Sun. Although strong fields are thought inhibit coronal mass ejections (CMEs), dimming signatures typically associated an eruptive CME were recently observed in Dor. The uninterrupted, long-duration signal suggests took place at high latitude, where it remained view as rotates. A high-latitude also consistent observations indicate hosts polar active regions. To...
ABSTRACT Observations of polarization position angle ($\theta$) standards made from 2014 to 2023 with the High Precision Polarimetric Instrument (HIPPI) and other HIPPI-class polarimeters in both hemispheres are used investigate their variability. Multiband data were first thoroughly recalibrate instrument performance by bench-marking against carefully selected literature data. A novel co-ordinate difference matrix (CDM) approach – which combines pairs points was then amalgamate...
Solar-type stars form with a wide range of rotation rates. A persists until stellar age 0.6 Gyr, after which solar-type exhibit Skumanich spin-down. Rotational evolution models incorporating polytropic winds struggle to simultaneously reproduce these two regimes, namely the initially and spin-down without imposing an a-priori cap on wind mass-loss rate. We show that three-dimensional model driven by Alfv\'en waves observational data yields torques agree observed distribution In our Sun...
Solar-type stars, which shed angular momentum via magnetised stellar winds, enter the main sequence with a wide range of rotational periods $P_\text{rot}$. This initially contracts and has mostly vanished by age $t\sim0.6$ Gyr, after stars spin according to Skumanich relation $P_\text{rot}\propto\sqrt t$. Magnetohydrodynamic wind models can improve our understanding this convergence rotation periods. We present fifteen young aged from 24 Myr 0.13 Gyr. With previous 0.26 Gyr 0.6 we obtain...