A5020516122- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- History and Developments in Astronomy
- High-pressure geophysics and materials
- Adaptive optics and wavefront sensing
- Geophysics and Gravity Measurements
- Spectroscopy and Chemometric Analyses
- Computational Physics and Python Applications
- Spacecraft and Cryogenic Technologies
- Radio Astronomy Observations and Technology
- Planetary Science and Exploration
- Innovative Microfluidic and Catalytic Techniques Innovation
- Modern American Literature Studies
- Fluid Dynamics and Vibration Analysis
- Seismic Waves and Analysis
- Gaussian Processes and Bayesian Inference
- Parallel Computing and Optimization Techniques
- Experimental and Theoretical Physics Studies
Lund University
2014-2023
Lund Science (Sweden)
2022
University of Copenhagen
2020
Max Planck Institute for Astronomy
2019
Max Planck Society
2019
Monash University
2006-2018
University of Cambridge
2005-2014
Australian Astronomical Observatory
2013
University of Bonn
2010-2013
Université Libre de Bruxelles
2010
Abstract The Laser Interferometer Space Antenna (LISA) will be a transformative experiment for gravitational wave astronomy, and, as such, it offer unique opportunities to address many key astrophysical questions in completely novel way. synergy with ground-based and space-born instruments the electromagnetic domain, by enabling multi-messenger observations, add further discovery potential of LISA. next decade is crucial prepare community LISA’s first observations. This review outlines...
We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for four-metre-class Visible and Infrared Survey Astronomy (VISTA) at Paranal. Its key specifications are: large field of view (FoV) 4.2 square degrees high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs ($R = λ/Δλ\sim 6500$), 812 transferring light to high-resolution spectrograph \sim 20\,000$). After...
The planet candidates discovered by the Kepler mission provide a rich sample to constrain architectures and relative inclinations of planetary systems within approximately 0.5 AU their host stars. We use triple-transit from 16-months data as templates for physical triple-planet perform synthetic transit observations. find that all double-transit can be produced templates, given low mutual inclination around five degrees. Our analysis shows contains population planets larger than four Earth...
We perform hydrodynamic simulations of mass transfer in binaries that contain a white dwarf and neutron star (WD–NS binaries), measure the specific angular momentum material lost from binary disc winds. By incorporating our results within long-term evolution model, we stability these binaries. find only containing helium dwarfs (WDs) with masses less than critical MWD, crit = 0.2 M⊙ undergo stable evolve into ultracompact X-ray Systems higher WDs experience unstable transfer, which leads to...
The stars that populate the solar neighbourhood were formed in stellar clusters. Through N-body simulations of these clusters, we measure rate close encounters between stars. By monitoring interaction histories each star, investigate singleton fraction neighbourhood. A is a star which as single has never experienced any with other or binaries, undergone an exchange encounter binary. We find that, stars, significant not singletons once clusters have dispersed. If some had planetary systems,...
In recent years much interest has been shown in the process of thermohaline mixing red giants. low- and intermediate-mass stars this mechanism first activates at position bump luminosity function, identified as a likely candidate for driving slow inferred to occur these stars. One particularly important consequence process, which is driven by molecular weight inversion, destruction lithium. We show that degree lithium destruction, or some cases production, extremely sensitive numerical...
Instabilities in planetary systems can result the ejection of planets from their host system, resulting free-floating (FFPs). If this occurs a star cluster, FFP may remain bound to cluster for some time and interact with other members until it is ejected. Here, we use $N$-body simulations characterise close star-planet planet-planet encounters dynamical fate population clusters containing $500-2000$ single or binary members. We find that FFPs ejected system at low velocities typically leave...
We analyse N-body simulations of star-forming regions to investigate the effects external far and extreme ultra-violet photoevaporation from massive stars on protoplanetary discs. By varying initial conditions simulated regions, such as spatial distribution, net bulk motion (virial ratio), density, we which parameters most affect rate at discs are dispersed due photoevaporation. find that disc dispersal is faster in highly substructured than smooth centrally concentrated regions. Sub-virial...
Context. Binary stellar systems form a large fraction of the Galaxy’s stars. They are useful as laboratories for studying physical processes taking place within stars, and must be correctly taken into account when observations stars used to study structure evolution Galaxy. The advent large-scale spectroscopic photometric surveys allows us obtain samples binaries that permit characterising their populations. Aims. We aim sample double-lined (SB2s) by analysis spectra from GALAH survey in...
ABSTRACT We conduct the first 3D hydrodynamic simulations of oxygen–neon white dwarf–neutron star/black hole mergers (ONe WD–NS/BH mergers). Such constitute a significant fraction, and may even dominate, inspiral rates all WD–NS binaries. post-process our to obtain nuclear evolution these systems couple results supernova spectral synthesis code light curves spectra for transients. find that amount 56Ni synthesized in grows as strong function WD mass, reaching typically 0.05 up $0.1\, {\rm...
There is an apparent dichotomy between the metal-poor ([Fe/H] <= -2) yet carbon-normal giants and their carbon-rich counterparts. The former undergo significant depletion of carbon on red giant branch after they have undergone first dredge-up, whereas latter do not appear to experience depletion. We investigate this in context that extra mixing occurs via thermohaline instability arises due burning helium-3. present evolution [C/Fe], [N/Fe] carbon-12/carbon-13 for three models: a star,...
We show that collisions with stellar-mass black holes can partially explain the absence of bright giant stars in Galactic Centre, first noted by Genzel et al. missing objects are low-mass giants and asymptotic branch range 1–3 M⊙. Using detailed stellar evolution calculations, we find to prevent these from evolving become visible depleted K bands, require they suffer on red branch, calculate fractional envelope mass losses required. a combination smoothed particle hydrodynamic restricted...
It is now widely accepted that globular cluster red giant branch (RGB) stars owe their strange abundance patterns to a combination of pollution from progenitor and in situ extra mixing. In this hybrid theory first generation imprints into the gas which second forms. The suggests mixing operating both populations we use variation [C/Fe] with luminosity examine how efficient is. We investigate observed RGBs M3, M13, M92, M15, NGC 5466 as means test thermohaline parameter pair M3 M13 are...
We use N-body simulations of star cluster evolution to explore the hypothesis that short-lived radioactive isotopes found in meteorites, such as 26Al, were delivered Sun's protoplanetary disc from a supernova at epoch Solar system formation. cover range formation parameter space and model both clusters with primordial substructure those smooth profiles. also adopt different initial virial ratios – cool, collapsing warm, expanding associations. In each cluster, we place same stellar...
We present the observed offsets of short-duration gamma-ray bursts (SGRBs) from their putative host galaxies and compare them to expected distributions merging compact object binaries, given properties hosts. find that for all but one burst in our sample are consistent with this model. For case massive elliptical galaxies, circular velocities hosts' haloes exceed natal almost binaries. Hence extents predicted offset determined largely by spatial extents. In contrast, spiral hosts galactic...
We present deep VLT and HST observations of the nearest examples calcium-rich 'gap' transients -- rapidly evolving transient events, with a luminosity intermediate between novae supernovae. These sources are frequently found at large galactocentric offsets, their progenitors remain mysterious. Our find no convincing underlying quiescent coincident locations these transients, allowing us to rule out number potential progenitor systems. The presence surviving massive-star binary companions (or...
HR 8799 is a star accompanied by four massive planets on wide orbits. The observed planetary configuration has been shown to be unstable timescale much shorter than the estimated age of system (~ 30 Myr) unless are locked into mean motion resonances. This condition characterised small-amplitude libration one or more resonant angles that stabilise preventing close encounters. We simulate systems similar system, exploring parameter space in separation between orbits, masses and distance from...
Could the velocity spread, increasing with time, in Galactic disk be explained as a result of gravitational interactions stars giant molecular clouds (GMCs) and spiral arms? Do old open clusters high above plane provide clues to this question? We explore effects on stellar orbits scattering by inhomogeneities potential due GMCs, arms bar, whether high-altitude could have formed closer later been scattered. Simulations test-particle motions are performed realistic potential. The internal...
In the era of large-scale surveys stars in Milky Way, stellar ages are crucial for studying evolution Galaxy. But determining field is notoriously difficult; therefore, we attempt to determine benchmark extensively studied Gaia which can be used validation purposes. By searching literature age estimates from different methods and deriving new based on Bayesian isochrone fitting, able put reliable limits 16 out 33 stars. The giants with well-defined all young, an expansion sample include...
The Laser Interferometer Space Antenna (LISA) will be a transformative experiment for gravitational wave astronomy, and, as such, it offer unique opportunities to address many key astrophysical questions in completely novel way. synergy with ground-based and space-born instruments the electromagnetic domain, by enabling multi-messenger observations, add further discovery potential of LISA. next decade is crucial prepare community LISA's first observations. This review outlines extensive...
The formation mechanism of the barium stars is thought to be well understood. Barium-rich material, lost in a stellar wind from thermally-pulsing asymptotic-giant branch star binary system, accreted by its companion main-sequence star. Now, many millions years later, primary an unseen white dwarf and secondary has itself evolved into giant which displays absorption lines spectrum what we call A similar wind-accretion also form low-metallicity CH carbon-enhanced metal-poor stars....
We review the observational evidence for extra mixing in stars on red giant branch (RGB) and discuss why thermohaline is a strong candidate mechanism. recall simple phenomenological description of aspects general. use observations M3 to constrain form diffusion coefficient any associated free parameters. This done by matching [C/Fe] [N/Fe] along RGB M3. After taking into account presumed initial primordial bimodality CN-weak CN-strong stars, our models can explain full spread [C/Fe]....
Calcium-rich supernovae represent a significant challenge for our understanding of the fates stellar systems. They are less luminous than other supernova (SN) types and they evolve more rapidly to reveal nebular spectra dominated by strong calcium lines with weak or absent signatures intermediate- iron-group elements, which seen in SNe. Strikingly, their explosion sites also mark them out as distinct from SN types. Their galactocentric offset distribution is strongly skewed very large...
ESA recently called for new "Science Ideas" to be investigated in terms of feasibility and technological developments -- technologies not yet sufficiently mature. These ideas may the future become candidates M or L class missions within Science Program. With launch Gaia December 2013, Europe entered a era space astrometry following footsteps very successful Hipparcos mission from early 1990s. is successor Hipparcos, both which operated optical wavelengths, two orders magnitude more accurate...