Speaker : Damien Gratadour
Title: Bridging Astronomy, HPC and AI in giant telescopes from the optical to radio frequencies
Abstract: Frontier computing has become a key enabler for scientific discovery, at the core of the next generation of extremely large multi-science hubs, such as the SKA Observatory or the European Extremely Large Telescope. I will present current efforts and the future roadmap we are contemplating, bridging astronomy with HPC and AI technologies to contribute to these major scientific infrastructures, in particular through the soon to be established ECLAT joint lab, a collaborative effort between CNRS, Inria and Atos. Beyond technical aspects related to increasing the scientific return of these facilities, I will also cover transverse topics such as energy efficiency and operational cost containment.
Speaker : Christine Ducourante (LAB)
Title: Gaia explore l’Univers profond: Galaxies, quasars et lentilles gravitationnelles
Abstract:
Speaker : Lars Bonne (USRA)
Title: Probing the assembly and dispersal of molecular clouds with the [CII] fine structure line
Abstract:
I will present high spectral resolution observations of the ionized carbon fine structure line at 158 μm ([CII]) from the SOFIA FEEDBACK legacy survey. [CII] is a unique tracer of the CO-dark molecular gas and photodissociation regions (PDRs) at the surface of molecular clouds. The FEEDBACK survey maps the [CII] line in 11 Galactic high-mass star forming regions. First, I will present the [CII] observations of the DR21 ridge in Cygnus-X. There, [CII] unveils that the assembly of this massive star forming ridge is the result of a high-velocity (~20 km/s) colliding flow. This collision also curves the magnetic field around the ridge and thus sets the cloud geometry. Further investigating the molecular cloud dynamics with IRAM 30m observations shows that this rapid mass accumulation initiates gravitational collapse of the full molecular cloud. Then, I will present studies focusing on regions that experience the effect of stellar feedback from high-mass stars. In these regions, [CII] unveils high-velocity mass ejection from the clouds that is not seen in CO. Quantifying the mass ejection rate shows that stellar feedback can disperse these star forming clouds in a few Myr. These results point to a consistent scenario for molecular cloud evolution and star formation on relatively short timescales. Far-infrared fine structure lines are thus important tools to pin down the physical processes that drive the evolution of the interstellar medium (ISM).
Speaker : Pamela Freeman
Title: The Carbon-based Molecules of High Mass Star Forming Regions AFGL 2591 and IRAS 20126
Abstract:
There is a diverse chemical inventory in protostellar regions that has led to the classification of two extreme types of systems: hot corinos, for the hot and dense low-mass systems that contain complex organic molecules, and warm carbon chain chemistry sources, for the warm and dense regions near a protostar containing unsaturated carbon chain molecules. Since these definitions were presented by Ceccarelli et al. (2004) and Sakai et al. (2008), respectively, there has been a growing field to detect these sources and determine if these classes of molecules can co-exist. There have been few studies surveying these molecules in high mass star forming regions—places of significance as the birthplace of most stars. To address this, I have conducted spectral surveys in two high-mass star forming regions in Cygnus X—AFGL 2591 and IRAS 20126—with the Green Bank Telescope and the IRAM 30m Telescope. In these observations, I detect several lines of formaldehyde, H2CO, and methanol, CH3OH, as tracers of hot core chemistry, and several lines of propyne, CH3CCH, and cyclopropenylidene, c-C3H2, as tracers of carbon chain chemistry. With a local thermodynamic equilibrium model, I use the observed molecular spectra to determine the physical conditions of these regions, producing maps of the gas temperatures, column densities, and velocities. These results illuminate the possible physical and dynamical environments of complex organic and carbon chain molecules, and are an initial step in investigating the chemical evolution of carbon-based molecules in star forming regions. The chemical makeup of star forming clouds and protostellar systems leads directly into that of stellar and planetary systems; observing the chemical complexity of star formation and modeling its environment provides an invaluable link between these systems.
Speaker : Marcel Agueros (Univ. de Columbia)
Title: Studying Low-Mass Stars in the Era of Surveys: Data, Models, and Surprises
Abstract: Stellar ages are notoriously difficult to measure accurately for main-sequence low-mass stars, which limits our ability to address questions ranging from the evolutionary state of exoplanets to the chemical history of the Galaxy. Gyrochronology, which uses stellar rotation as a proxy for age, is a promising solution to this quandary. Unfortunately, however, empirical and theoretical models of the age-rotation relation have been hampered by a lack of rotational measurements for large numbers of low-mass stars with a wide range of well-known ages. We are still far from being able to describe fully the evolution of rotation for low-mass stars, or from being able to use rotation measurements to estimate accurately the ages of isolated field stars. I will summarize recent ground-based and space-based work to characterize the rotational behavior of G, K, and M dwarfs in open clusters ranging in age from 125 Myr (the Pleiades) to 3 Gyr (Ruprecht 147), and then compare these data to each other and to models for stellar spin-down to appraise our current understanding of the age-rotation relation. I will also touch on an on-going survey targeting newly discovered single-aged stellar populations to address the broader age-rotation-activity relation.
Speaker : Jacques Taillard
Title: La nuit gardienne de notre sommeil et de notre santé
Abstract: Le cycle veille sommeil est sous le contrôle des horloges biologiques qui vont imposer la période de sommeil et d’éveil au cours de la journée et donc l’heure de coucher et l’heure de réveil. Grace aux horloges biologiques, ces périodes d’éveil et de sommeil, mais également les processus physiologiques, seront parfaitement en phase (synchronisés) avec le rythme lumière/obscurité et ainsi nos comportements seront en totale harmonie avec notre environnement. L’horloge biologique principale est localisée dans le cerveau. Cette horloge fonctionne avec une périodicité légèrement supérieure à 24hr, elle doit être donc remise à l’heure tous les jours par différents synchroniseurs. C’est surtout le cycle lumière/obscurité, en particulier la lumière solaire ou artificielle, qui va agir sur le fonctionnement de l’horloge biologique. Ainsi, une exposition à la lumière au mauvais moment de la journée, la nuit par exemple, peut désynchroniser l’horloge biologique. Notre mode de vie moderne va également contribuer à une mauvaise synchronisation entre notre temps social et notre temps biologique. La lumière artificielle nocturne et nos comportements contribuent à des dérèglements qui vont agir sur notre sommeil, notre santé et notre bien-être. L’objectif de cette conférence est de vous éclairer sur les bienfaits ou les méfaits de la lumière sur notre santé mais aussi vous donner les bons comportements à adopter pour améliorer votre sommeil.
Jacques Taillard
Ingénieur de recherche CNRS
UMR 6033 SANPSY, Sommeil, addiction et neuropsychiatrie
Speaker : Robert Simon (I. Physikalisches Institut Köln)
Title: The cycling of matter from the interstellar medium to stars and back: The CCAT-prime Galactic Ecology project
Abstract: The Fred Young Submillimeter Telescope (FYST) at the CCAT observatory will be a novel 6 m aperture telescope enabling highly sensitive wide field observations at submillimeter wavelengths to address science topics ranging from the formation of molecular clouds and stars, the evolution of the interstellar medium (ISM) in the Milky Way and nearby galaxies, to galaxies in the early universe and cosmology.
The telescope will be deployed near the summit of Cerro Chajnantor at 5600 m altitude in the Chilean Atacama desert and become operational in late 2024. The CCAT-prime Galactic Ecology project (GEco) is one of the key science projects of the observatory designed to study the formation and evolution of molecular clouds in the Milky Way, the Magellanic clouds, and other nearby galaxies through submm spectroscopy. The GEco project will do this with dedicated large scale surveys in spectrally resolved lines of CO (J=4-3 and 7-6) and atomic carbon ([CI] 1-0 and 2-1) that become possible with the novel large format CCAT-prime Heterodyne Array Instrument (CHAI). I will introduce our planned observations and the science that GEco will address.
Speaker : Sacha Gavino
Title: Shaping the CO snowline in protoplanetary disks
Abstract: Characterizing the dust thermal structure in protoplanetary disks is a fundamental task as the dust temperature can affect both the disk chemical evolution and planet formation. It is a challenging task, however, since the temperature is strongly dependent on many parameters, including the grain size distribution. We investigate the effects of the radiative interactions between multiple dust populations on the CO distribution using dedicated thermochemical disk models. We find that the interaction of the dust scattered light between at least two dust grain populations can produce a complex temperature structure. In particular, the scattered light is sufficient to significantly raise the temperature of micron-sized grains in the midplane. This results in the splitting of the CO snowline that can strongly reshuffle the distribution of both CO in the gas-phase and on the grain surface.
Speaker : Donghui Quan (Zhejiang Laboratory)
Title: Modelling Interstellar Prebiotic Molecules: Hydroxylamine (NH2OH), Cyanamide (NH2CN), and Carbodiimide (HNCNH)
Abstract:
Interstellar molecules, commonly referred to as molecules found in the interstellar medium and circumstellar shells, have had around 300 molecules identified thus far (Müller et al., 2023). Over a third of these molecules are complex organic molecules, also known as COMs, revealing a broad range of complex chemistry found in various astronomical sources. Additionally, some interstellar molecules, particularly organic ones, act as precursors for biological molecules like amino acids and nucleosides, which astrophysicists find fascinating. These molecules are called prebiotic molecules and are primarily detected in star-forming areas, as well as quiescent clouds with nearby shocks.
Our research project utilizes computer-assisted modelling using chemical kinetics rate equations. We focus on hydroxylamine (NH2OH), cyanamide (NH2CN), and carbodiimide (HNCNH) isomers, which are known to act as precursors to amino acids or nucleosides. Our models provide an insight into the physical environments and associated chemical/physical processes of these species and related molecules. We identify primary formation and destruction reactions, optimal physical conditions for detecting these molecules, and related molecules. All these information may help with our understanding of astrochemistry in interstellar space, and enrich our knowledge of the complexity of the universe.