Project acronym ASSESS
Project Episodic Mass Loss in the Most Massive Stars: Key to Understanding the Explosive Early Universe
Researcher (PI) Alceste BONANOS
Host Institution (HI) NATIONAL OBSERVATORY OF ATHENS
Call Details Consolidator Grant (CoG), PE9, ERC-2017-COG
Summary 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.
Summary
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.
Max ERC Funding
1 128 750 €
Duration
Start date: 2018-09-01, End date: 2023-08-31
Project acronym MINATRAN
Project Probing the Micro-Nano Transition: Theoretical and Experimental Foundations, Simulations and Applications
Researcher (PI) Aikaterini Aifanti
Host Institution (HI) ARISTOTELIO PANEPISTIMIO THESSALONIKIS
Call Details Starting Grant (StG), PE6, ERC-2007-StG
Summary The objective is to develop a robust multifunctional framework/probe for capturing the evolution of deformation and failure in a variety of processes at the micro-nano transition regime. An interdisciplinary approach will be pursued based on fundamental theory and experiment, in conjunction with multiscale simulations for micro/nanotechnology applications. The approach is unconventional as it ventures to extend continuum mechanics down to the micro/nano regime and verify this through nanoindentation and atomic force microscopy techniques. It is also unique as the new phenomenology introduced for establishing this extension (higher order gradients accounting for microscopic processes and interfacial energy terms accounting for nanoscopic phenomena) will be substantiated through hybrid (ab initio-atomistic-defect-finite element) simulations. The framework will be employed to consider fracture and size effects in a number of micro-nano scale transition configurations ranging from nanograined aggregates and nanolayered structures to nanotubes and micropillars, and from Li-ion battery electrodes to bioactive interfaces. Other micro/nano objects such as quantum dots, nanowires and NEMS/MEMS devices, as well as biomolecular microcrystalline membranes leading to living cell division will be considered. In a sense this “scale” transition theory is reminiscent in scope to Landau’s “phase” transition theory where a variety of different physical phenomena can be treated within a common framework. This optimism stems from the PI’s previous success with this approach, as well as Smalley’s remark that the “laws of continuum mechanics are amazingly robust for treating even intrinsically discrete objects only a few atoms in diameter”. A good mix of young researchers and mature scholars will be employed, thus connecting people and ideas through joint publications and scholarly activities in a critical area of fundamental and applied research.
Summary
The objective is to develop a robust multifunctional framework/probe for capturing the evolution of deformation and failure in a variety of processes at the micro-nano transition regime. An interdisciplinary approach will be pursued based on fundamental theory and experiment, in conjunction with multiscale simulations for micro/nanotechnology applications. The approach is unconventional as it ventures to extend continuum mechanics down to the micro/nano regime and verify this through nanoindentation and atomic force microscopy techniques. It is also unique as the new phenomenology introduced for establishing this extension (higher order gradients accounting for microscopic processes and interfacial energy terms accounting for nanoscopic phenomena) will be substantiated through hybrid (ab initio-atomistic-defect-finite element) simulations. The framework will be employed to consider fracture and size effects in a number of micro-nano scale transition configurations ranging from nanograined aggregates and nanolayered structures to nanotubes and micropillars, and from Li-ion battery electrodes to bioactive interfaces. Other micro/nano objects such as quantum dots, nanowires and NEMS/MEMS devices, as well as biomolecular microcrystalline membranes leading to living cell division will be considered. In a sense this “scale” transition theory is reminiscent in scope to Landau’s “phase” transition theory where a variety of different physical phenomena can be treated within a common framework. This optimism stems from the PI’s previous success with this approach, as well as Smalley’s remark that the “laws of continuum mechanics are amazingly robust for treating even intrinsically discrete objects only a few atoms in diameter”. A good mix of young researchers and mature scholars will be employed, thus connecting people and ideas through joint publications and scholarly activities in a critical area of fundamental and applied research.
Max ERC Funding
1 128 400 €
Duration
Start date: 2008-10-01, End date: 2013-09-30
Project acronym PAGE
Project The role of mRNA-processing bodies in ageing
Researcher (PI) Popi Syntichaki
Host Institution (HI) IDRYMA IATROVIOLOGIKON EREUNON AKADEMIAS ATHINON
Call Details Starting Grant (StG), LS3, ERC-2007-StG
Summary Recently, we and others have revealed that, in the nematode Caenorhabditis elegans, reduction of protein synthesis rates in somatic cells extends lifespan. Based on this, we postulate that the molecular factors and mechanisms that control the mRNA metabolism in post-mitotic cells are critical determinants of ageing. This project will validate this hypothesis using C. elegans as main model system, but parallel studies in Saccharomyces cerevisiae and Drosophila melanogaster will prove the conservation of our observations. The cellular factors involved in mRNA metabolism (degradation/storage) are localized at specific particles in the cytoplasm of all eukaryotic cells, termed mRNA processing (P) bodies. Additionally, stress granules are cytoplasmic sites of mRNA-metabolism that are formed under stress conditions in mammalian cells. The objectives of this project include: -Monitoring of both P bodies and stress granules in adult worms and characterization of the age-related alterations in their profile, by immunostaining and real-time fluorescence imaging -Direct alterations in the expression of genes encoding factors of each particle in wild-type worms and analysis of the effects on lifespan and stress resistance -Comparison of the age-related changes in the profile of P bodies and stress granules between wild-type and long- or short-lived mutant worms -Direct alterations in the expression of genes encoding factors of each particle in worms with altered lifespan and investigation of the effects on lifespan and stress resistance -Observation of the age-related alterations in the profile of P bodies in yeast and flies, both in wild-type and long-lived strains. The rationale for this project is to provide insight into the modulation of ageing and stress resistance at the level of mRNA metabolism, which is a yet unexplored field of the biology of ageing and global stress response.
Summary
Recently, we and others have revealed that, in the nematode Caenorhabditis elegans, reduction of protein synthesis rates in somatic cells extends lifespan. Based on this, we postulate that the molecular factors and mechanisms that control the mRNA metabolism in post-mitotic cells are critical determinants of ageing. This project will validate this hypothesis using C. elegans as main model system, but parallel studies in Saccharomyces cerevisiae and Drosophila melanogaster will prove the conservation of our observations. The cellular factors involved in mRNA metabolism (degradation/storage) are localized at specific particles in the cytoplasm of all eukaryotic cells, termed mRNA processing (P) bodies. Additionally, stress granules are cytoplasmic sites of mRNA-metabolism that are formed under stress conditions in mammalian cells. The objectives of this project include: -Monitoring of both P bodies and stress granules in adult worms and characterization of the age-related alterations in their profile, by immunostaining and real-time fluorescence imaging -Direct alterations in the expression of genes encoding factors of each particle in wild-type worms and analysis of the effects on lifespan and stress resistance -Comparison of the age-related changes in the profile of P bodies and stress granules between wild-type and long- or short-lived mutant worms -Direct alterations in the expression of genes encoding factors of each particle in worms with altered lifespan and investigation of the effects on lifespan and stress resistance -Observation of the age-related alterations in the profile of P bodies in yeast and flies, both in wild-type and long-lived strains. The rationale for this project is to provide insight into the modulation of ageing and stress resistance at the level of mRNA metabolism, which is a yet unexplored field of the biology of ageing and global stress response.
Max ERC Funding
1 080 000 €
Duration
Start date: 2008-09-01, End date: 2014-08-31
Project acronym PASIPHAE
Project Overcoming the Dominant Foreground of Inflationary B-modes: Tomography of Galactic Magnetic Dust via Measurements of Starlight Polarization
Researcher (PI) Konstantinos TASSIS
Host Institution (HI) IDRYMA TECHNOLOGIAS KAI EREVNAS
Call Details Consolidator Grant (CoG), PE9, ERC-2017-COG
Summary An inflation-probing B-mode signal in the polarization of the cosmic microwave background (CMB) would be a discovery of utmost importance in physics. While such a signal is aggressively pursued by experiments around the world, recent Planck results have showed that this breakthrough is still out of reach, because of contamination from Galactic dust. To get to the primordial B-modes, we need to subtract polarized emission of magnetized interstellar dust with high accuracy. A critical piece of this puzzle is the 3D structure of the magnetic field threading dust clouds, which cannot be accessed through microwave observations alone, since they record integrated emission along the line of sight. Instead, observations of a large number of stars at known distances in optical polarization, tracing the same CMB-obscuring dust, can map the magnetic field between them. The Gaia mission is measuring distances to a billion stars, providing an opportunity to produce, the first-ever tomographic map of the Galactic magnetic field, using optical polarization of starlight. Such a map would not only boost CMB polarization foreground removal, but it would also have a profound impact in a wide range of astrophysical research, including interstellar medium physics, high-energy astrophysics, and galactic evolution. Taking advantage of our privately-funded, novel-technology, high-accuracy WALOP optopolarimeters currently under construction, we propose an ambitious optopolarimetric program of unprecedented scale that can meet this challenge: a survey of both northern and southern Galactic polar regions targeted by CMB experiments, covering >10,000 square degrees, which will measure linear optical polarization at 0.2% accuracy of over 360 stars per square degree (over 3.5M stars, a 1000-fold increase over the state of the art), combining wide-field-optimized instruments and an extraordinary commitment of observing time by Skinakas Observatory and the South African Astronomical Observatory.
Summary
An inflation-probing B-mode signal in the polarization of the cosmic microwave background (CMB) would be a discovery of utmost importance in physics. While such a signal is aggressively pursued by experiments around the world, recent Planck results have showed that this breakthrough is still out of reach, because of contamination from Galactic dust. To get to the primordial B-modes, we need to subtract polarized emission of magnetized interstellar dust with high accuracy. A critical piece of this puzzle is the 3D structure of the magnetic field threading dust clouds, which cannot be accessed through microwave observations alone, since they record integrated emission along the line of sight. Instead, observations of a large number of stars at known distances in optical polarization, tracing the same CMB-obscuring dust, can map the magnetic field between them. The Gaia mission is measuring distances to a billion stars, providing an opportunity to produce, the first-ever tomographic map of the Galactic magnetic field, using optical polarization of starlight. Such a map would not only boost CMB polarization foreground removal, but it would also have a profound impact in a wide range of astrophysical research, including interstellar medium physics, high-energy astrophysics, and galactic evolution. Taking advantage of our privately-funded, novel-technology, high-accuracy WALOP optopolarimeters currently under construction, we propose an ambitious optopolarimetric program of unprecedented scale that can meet this challenge: a survey of both northern and southern Galactic polar regions targeted by CMB experiments, covering >10,000 square degrees, which will measure linear optical polarization at 0.2% accuracy of over 360 stars per square degree (over 3.5M stars, a 1000-fold increase over the state of the art), combining wide-field-optimized instruments and an extraordinary commitment of observing time by Skinakas Observatory and the South African Astronomical Observatory.
Max ERC Funding
1 887 500 €
Duration
Start date: 2018-06-01, End date: 2023-05-31
Project acronym RIMACO
Project Rigorous Mathematical Connections between the Theory of Computations and Statistical Physics
Researcher (PI) Dimitris Achlioptas
Host Institution (HI) INSTITOUTO TECHNOLOGIAS YPOLOGISTONKAI EKDOSEON DIOFANTOS
Call Details Starting Grant (StG), PE1, ERC-2007-StG
Summary The proposed research aims to enhance the study of randomness in computation by using ideas of statistical physics. In particular, it aims to place the connection between computation and statistical physics --- the subject of wide heuristic discussion for more than three decades --- on rigorous mathematical ground. Its main methodological vehicle is the study of random Constraint Satisfaction Problems (CSPs). CSPs are the common abstraction of numerous real-life problems and occur in areas ranging from aerospace design to biochemistry. Their ubiquity makes the design of efficient algorithms for CSPs extremely important. At the foundation of this endeavor lies the question of why certain CSP instances are exceptionally hard while other, seemingly similar, instances are easy. Probability distributions over instances allow us to study this phenomenon in a principled way, with each CSP distribution controlled by its ratio of constrains to variables (known as constraint density). By now, it has been established that random CSPs have solutions at densities much beyond the reach of any known efficient algorithm. Understanding the origin of this gap and designing algorithms that overcome it is the main focus of the proposed research. Ideas from statistical physics will play an important role here. Specifically, in recent years, physicists have proposed a heuristic but deep theory for the evolution of the solution-space geometry of random CSPs according to which algorithmic barriers correspond to phase transitions in this evolution. Examining the validity of the physics theory is a major research undertaking that must develop and reconcile notions shared by computation and statistical physics, e.g., the role of long-range correlations. A rigorous mathematical theory of such notions will enable a much more energetic exchange of ideas between the two fields, and has the potential to bring substantial fresh ideas to the study of efficient computation.
Summary
The proposed research aims to enhance the study of randomness in computation by using ideas of statistical physics. In particular, it aims to place the connection between computation and statistical physics --- the subject of wide heuristic discussion for more than three decades --- on rigorous mathematical ground. Its main methodological vehicle is the study of random Constraint Satisfaction Problems (CSPs). CSPs are the common abstraction of numerous real-life problems and occur in areas ranging from aerospace design to biochemistry. Their ubiquity makes the design of efficient algorithms for CSPs extremely important. At the foundation of this endeavor lies the question of why certain CSP instances are exceptionally hard while other, seemingly similar, instances are easy. Probability distributions over instances allow us to study this phenomenon in a principled way, with each CSP distribution controlled by its ratio of constrains to variables (known as constraint density). By now, it has been established that random CSPs have solutions at densities much beyond the reach of any known efficient algorithm. Understanding the origin of this gap and designing algorithms that overcome it is the main focus of the proposed research. Ideas from statistical physics will play an important role here. Specifically, in recent years, physicists have proposed a heuristic but deep theory for the evolution of the solution-space geometry of random CSPs according to which algorithmic barriers correspond to phase transitions in this evolution. Examining the validity of the physics theory is a major research undertaking that must develop and reconcile notions shared by computation and statistical physics, e.g., the role of long-range correlations. A rigorous mathematical theory of such notions will enable a much more energetic exchange of ideas between the two fields, and has the potential to bring substantial fresh ideas to the study of efficient computation.
Max ERC Funding
749 996 €
Duration
Start date: 2008-07-01, End date: 2014-06-30
Project acronym TRICEPS
Project Time-resolved Ring-Cavity-Enhanced Polarization Spectroscopy: Breakthroughs in measurements of a) Atomic Parity Violation, b) Protein conformation and biosensing and c) surface and thin film dynamics
Researcher (PI) Theodore Peter Rakitzis
Host Institution (HI) FOUNDATION FOR RESEARCH AND TECHNOLOGY HELLAS
Call Details Starting Grant (StG), PE2, ERC-2007-StG
Summary Polarimetry is a crucial tool in both fundamental and applied physics, ranging from the measurement of parity nonconservation (PNC) in atoms, to the determination of biomolecule structure, and the probing of interfaces. These measurements tend to be extremely challenging as the change of the polarization of light is usually extremely small; typical differences in polarization states are of the order of 10^-5 to 10^-8. Current experimental techniques often require acquisition times of the order of seconds or, in the case of PNC, even many days, limiting the possibilities of time-resolved measurements. Here, I propose to develop optical-cavity-based techniques which will enhance measurements of the polarization sensitivity and/or the time-resolution by 3-6 orders of magnitude. Preliminary data from prototypes and feasibility studies are presented. I propose to demonstrate how these breakthroughs will revolutionize polarimetry, by addressing some of the most important multidisciplinary problems in fundamental physics, biophysics, and material science: a) Testing the limits of the Standard Model with atomic PNC measurements. Current PNC experiments, and more importantly theory, for cesium atoms are limited to precision of about 0.5%. The novel and robust experimental technique I am proposing here affords 4 orders-of-magnitude higher sensitivity, thus giving access to lighter atoms, where the theory can be better than 0.1%, for the most stringent test of the Standard Model, while seeking new physics. b) The measurement of protein folding dynamics. Highly sensitive time-resolved spectroscopic ellipsometry, providing novel dynamical information on protein folding: nanosecond resolved, position measurements of functional groups of surface proteins, which map out the time-dependent protein structure. c) Determination of thin film thickness and surface density with nanosecond resolution, for the study of processes such as laser ablation and polymer growth.
Summary
Polarimetry is a crucial tool in both fundamental and applied physics, ranging from the measurement of parity nonconservation (PNC) in atoms, to the determination of biomolecule structure, and the probing of interfaces. These measurements tend to be extremely challenging as the change of the polarization of light is usually extremely small; typical differences in polarization states are of the order of 10^-5 to 10^-8. Current experimental techniques often require acquisition times of the order of seconds or, in the case of PNC, even many days, limiting the possibilities of time-resolved measurements. Here, I propose to develop optical-cavity-based techniques which will enhance measurements of the polarization sensitivity and/or the time-resolution by 3-6 orders of magnitude. Preliminary data from prototypes and feasibility studies are presented. I propose to demonstrate how these breakthroughs will revolutionize polarimetry, by addressing some of the most important multidisciplinary problems in fundamental physics, biophysics, and material science: a) Testing the limits of the Standard Model with atomic PNC measurements. Current PNC experiments, and more importantly theory, for cesium atoms are limited to precision of about 0.5%. The novel and robust experimental technique I am proposing here affords 4 orders-of-magnitude higher sensitivity, thus giving access to lighter atoms, where the theory can be better than 0.1%, for the most stringent test of the Standard Model, while seeking new physics. b) The measurement of protein folding dynamics. Highly sensitive time-resolved spectroscopic ellipsometry, providing novel dynamical information on protein folding: nanosecond resolved, position measurements of functional groups of surface proteins, which map out the time-dependent protein structure. c) Determination of thin film thickness and surface density with nanosecond resolution, for the study of processes such as laser ablation and polymer growth.
Max ERC Funding
909 999 €
Duration
Start date: 2009-01-01, End date: 2014-12-31
