ERC FUNDED PROJECTS

"High-energy observations of our Galaxy offer a good, albeit not complete, picture of the X-ray source populations, in particular the accreting binary sources. Recent ability to study accreting binaries in nearby galaxies has shown that we would be short-sighted if we restricted ourselves to our Galaxy or to a few nearby ones. I propose an ambitious project that involves a comprehensive study of all the galaxies within 10 Mpc for which we can study in detail their X-ray sources and stellar populations. The study will combine data from a unique suite of observatories (Chandra, XMM-Newton, HST, Spitzer) with state-of-the-art theoretical modelling of binary systems. I propose a novel approach that links the accreting binary populations to their parent stellar populations and surpasses any current studies of X-ray binary populations, both in scale and in scope, by: (a) combining methods and results from several different areas of astrophysics (compact objects, binary systems, stellar populations, galaxy evolution); (b) using data from almost the whole electromagnetic spectrum (infrared to X-ray bands); (c) identifying and studying the different sub-populations of accreting binaries; and (d) performing direct comparison between observations and theoretical predictions, over a broad parameter space. The project: (a) will answer the long-standing question of the formation efficiency of accreting binaries in different environments; and (b) will constrain their evolutionary paths. As by-products the project will provide eagerly awaited input to the fields of gravitational-wave sources, γ-ray bursts, and X-ray emitting galaxies at cosmological distances and it will produce a heritage multi-wavelength dataset and library of models for future studies of galaxies and accreting binaries."

1 242 000 €

Start date: 2014-04-01, End date: 2019-03-31

A hot topic in today's debate on global warming is drag reduction in aeronautics. The most beneficial concept for drag reduction is to maintain the major portion of the airfoil laminar. Estimations show that the potential drag reduction can be as much as 15%, which would give a significant reduction of NOx and CO emissions in the atmosphere considering that the number of aircraft take offs, only in the EU, is over 19 million per year. An important element for successful flow control, which can lead to a reduced aerodynamic drag, is enhanced physical understanding of the transition to turbulence process. In previous wind tunnel measurements we have shown that roughness elements can be used to sensibly delay transition to turbulence. The result is revolutionary, since the common belief has been that surface roughness causes earlier transition and in turn increases the drag, and is a proof of concept of the passive control method per se. The beauty with a passive control technique is that no external energy has to be added to the flow system in order to perform the control, instead one uses the existing energy in the flow. In this project proposal, AFRODITE, we will take this passive control method to the next level by making it twofold, more persistent and more robust. Transition prevention is the goal rather than transition delay and the method will be extended to simultaneously control separation, which is another unwanted flow phenomenon especially during airplane take offs. AFRODITE will be a catalyst for innovative research, which will lead to a cleaner sky.

1 418 399 €

Start date: 2010-11-01, End date: 2015-10-31

Massive stars dominate their surroundings during their short lifetimes, while their explosive deaths impact the chemical evolution and spatial cohesion of their hosts. After birth, their evolution is largely dictated by their ability to remove layers of hydrogen from their envelopes. Multiple lines of evidence are pointing to violent, episodic mass-loss events being responsible for removing a large part of the massive stellar envelope, especially in low-metallicity galaxies. Episodic mass loss, however, is not understood theoretically, neither accounted for in state-of-the-art models of stellar evolution, which has far-reaching consequences for many areas of astronomy. We aim to determine whether episodic mass loss is a dominant process in the evolution of the most massive stars by conducting the first extensive, multi-wavelength survey of evolved massive stars in the nearby Universe. The project hinges on the fact that mass-losing stars form dust and are bright in the mid-infrared. We plan to (i) derive physical parameters of a large sample of dusty, evolved targets and estimate the amount of ejected mass, (ii) constrain evolutionary models, (iii) quantify the duration and frequency of episodic mass loss as a function of metallicity. The approach involves applying machine-learning algorithms to existing multi-band and time-series photometry of luminous sources in ~25 nearby galaxies. Dusty, luminous evolved massive stars will thus be automatically classified and follow-up spectroscopy will be obtained for selected targets. Atmospheric and SED modeling will yield parameters and estimates of time-dependent mass loss for ~1000 luminous stars. The emerging trend for the ubiquity of episodic mass loss, if confirmed, will be key to understanding the explosive early Universe and will have profound consequences for low-metallicity stars, reionization, and the chemical evolution of galaxies.

1 128 750 €

Start date: 2018-09-01, End date: 2023-08-31

ASTROFLOW aims to make ground-breaking progress in our physical understanding of exoplanetary mass loss, by quantifying the influence of stellar outflows on atmospheric escape of close-in exoplanets. Escape plays a key role in planetary evolution, population, and potential to develop life. Stellar irradiation and outflows affect planetary mass loss: irradiation heats planetary atmospheres, which inflate and more likely escape; outflows cause pressure confinement around otherwise freely escaping atmospheres. This external pressure can increase, reduce or even suppress escape rates; its effects on exoplanetary mass loss remain largely unexplored due to the complexity of such interactions. I will fill this knowledge gap by developing a novel modelling framework of atmospheric escape that will, for the first time, consider the effects of realistic stellar outflows on exoplanetary mass loss. My expertise in stellar wind theory and 3D magnetohydrodynamic simulations is crucial for producing the next-generation models of planetary escape. My framework will consist of state-of-the-art, time-dependent, 3D simulations of stellar outflows (Method 1), which will be coupled to novel 3D simulations of atmospheric escape (Method 2). My models will account for the major underlying physical processes of mass loss. With this, I will determine the response of planetary mass loss to realistic stellar particle, magnetic and radiation environments and will characterise the physical conditions of the escaping material. I will compute how its extinction varies during transit and compare synthetic line profiles to atmospheric escape observations from, eg, Hubble and our NASA cubesat CUTE. Strong synergy with upcoming observations (JWST, TESS, SPIRou, CARMENES) also exists. Determining the lifetime of planetary atmospheres is essential to understanding populations of exoplanets. ASTROFLOW’s work will be the foundation for future research of how exoplanets evolve under mass-loss processes.

1 999 956 €

Start date: 2019-09-01, End date: 2024-08-31