A5103062084- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Scientific Research and Discoveries
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Geophysics and Gravity Measurements
- Tribology and Lubrication Engineering
- Geomagnetism and Paleomagnetism Studies
- Phase Equilibria and Thermodynamics
- Gear and Bearing Dynamics Analysis
- Radio Astronomy Observations and Technology
- Eosinophilic Disorders and Syndromes
- Astrophysics and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Pulsars and Gravitational Waves Research
- Geological and Geophysical Studies
- Solar and Space Plasma Dynamics
- Spectroscopy and Laser Applications
- Ionosphere and magnetosphere dynamics
Galaxies, Etoiles, Physique et Instrumentation
2015-2024
Centre National de la Recherche Scientifique
2015-2024
Observatoire de Paris
2007-2024
Université Paris Sciences et Lettres
2016-2024
Université Paris Cité
2013-2024
Délégation Paris 7
2012-2024
Sorbonne Paris Cité
2016-2023
Janssen (France)
2009-2023
Novartis (Italy)
2015-2023
Institut d'Astrophysique de Paris
2019-2022
We analyze high quality abundances data of solar neighborhood stars and show that there are two distinct regimes [alpha/Fe] versus age which we identify as the epochs thick thin disk formation. A tight correlation between metallicity is clearly identifiable on stars, implying this population formed from a well mixed ISM, over time scale 4-5 Gyr. Thick vertical velocity dispersion correlate with age, youngest objects having small heights those stars. natural consequence these results gradient...
We investigate the enhancement of star formation efficiency in galaxy interactions and mergers by numerical simulations several hundred collisions. All morphological types along Hubble sequence are considered initial conditions two colliding galaxies, with varying bulge-to-disk ratios gas mass fractions. Different orbits simulated, direct retrograde, according to relative energy impact parameter, resulting history is compared that occuring galaxies when they isolated. Our principal results...
We investigate the nature of double color-magnitude sequence observed in Gaia DR2 HR diagram stars with high transverse velocities. The reddest-color are likely dominated by dynamically-hot tail thick disk population. Information from Nissen & Schuster (2010) and APOGEE survey suggests that blue-color have elemental abundance patterns can be explained this population having a relatively low star-formation efficiency during its formation. In dynamical orbital spaces, such as `Toomre diagram',...
Gaia Data Release 3 (Gaia DR3) contains the second release of combined radial velocities. It is based on spectra collected during first 34 months nominal mission. The longer time baseline and improvements pipeline made it possible to push processing limit, from Grvs = 12 in DR2, 14 mag. In this article, we describe new functionalities implemented for DR3, quality filters applied post-processing properties performance published For several were upgraded or added. (Abridged) DR3 velocities 33...
Previous studies based on the analysis of Gaia DR2 data have revealed that accreted stars, possibly originating from a single progenitor satellite, are significant component halo our Galaxy, potentially constituting most stars at $\rm [Fe/H] < -1$ within few kpc Sun and beyond. In this paper, we couple astrometric with elemental abundances APOGEE DR14 to characterize kinematics chemistry in-situ populations up \sim -2$. Accreted appear significantly impact Galactic chemo-kinematic relations,...
Abstract We present an atlas and follow-up spectroscopic observations of 87 thin stream-like structures detected with the STREAMFINDER algorithm in Gaia DR3, which 28 are new discoveries. Here, we focus on using these streams to refine mass models Galaxy. Fits a double-power-law halo outer power-law slope set − β h = −3 yield inner <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>−</mml:mo> <mml:msub> <mml:mi>γ</mml:mi> <mml:mi>h</mml:mi> </mml:msub>...
Abstract Chemical characterization of the Galactic center is essential for understanding its formation and structural evolution. Trends alpha ( α ) elements, such as magnesium, silicon, calcium, serve powerful diagnostic tools, offering insights into star rates gas-infall history. However, high extinction has previously hindered studies. In this study, we present a detailed chemical abundance analysis M giants in Milky Way's nuclear cluster (NSC), focusing on -element trends with...
We investigate the intensity enhancement and duration of starburst episodes triggered by major galaxy interactions mergers. analyze two large statistical datasets numerical simulations. These have been obtained using independent different techniques to model baryonic dark matter evolution that are extensively compared for first time. One is a Tree-SPH code, other one grid-based N-body sticky-particles code. show that, at low redshift, mergers in general trigger only moderate star formation...
We report the first robust measurement of Milky Way star formation history using imprint left on chemical abundances long-lived stars. The Galactic thick disk occurs during an intense phase between 9.0 (z ∼ 1.5) and 12.5 Gyr 4.5) ago is followed by a dip (at z 1.1) lasting about 1 Gyr. Our results imply that as massive Way's thin disk, suggesting fundamental role this component in genesis our Galaxy, something had been largely unrecognized. This new picture implies huge quantities gas...
We analyze the physical conditions in interstellar gas of 11 actively star-forming galaxies at z∼2, based on integral-field spectroscopy from ESO-VLT and Hubble Space Telescope/Near Infrared Camera Multi-Object Spectrometer imaging. concentrate high Hα surface brightnesses, large line widths, ratios, clumpy nature these galaxies. show that photoionization calculations emission diagnostics imply pressures densities are similar to most intense nearby regions z = 0 but over much larger scales...
Quenching, the cessation of star formation, is one most significant events in life cycle galaxies. We show here first evidence that Milky Way experienced a generalised quenching its formation at end thick disk $\sim$9 Gyr ago. Elemental abundances stars studied as part APOGEE survey reveal indeed less than $\sim$2 rate our Galaxy dropped by an order-of-magnitude. Because tight correlation between age and alpha abundance, this event reflects dearth along inner sequence [Fe/H]-[$α$/Fe] plane....
We investigate the evolution of galactic discs in N-body tree-SPH simulations. find that discs, initially truncated at three scale-lengths, can triple their radial extent, solely driven by secular evolution. At same time, initial metallicity gradients are flattened and even reversed outer discs. Both Type I (single exponential) II (down-turning) observed disc surface-brightness profiles be explained our findings. show with breaks beyond bar's Lindblad resonance, present only as effect...
We have recently identified a new radial migration mechanism resulting from the overlap of spiral and bar resonances in galactic disks. Here we confirm efficiency this fully self-consistent, Tree-SPH simulations, as well high-resolution pure N-body simulations. In all barred cases clearly identify effect spiral-bar resonance by measuring bimodality changes angular momentum disk, dL, whose maxima are near bar's corotation outer Lindblad resonance. This contrasts with smooth distribution dL...
We develop a chemical evolution model in order to study the star formation history of Milky Way. Our assumes that Way is formed from closed box-like system inner regions, while outer parts disc experience some accretion. Unlike usual procedure, we do not fix prescription (e.g. Kennicutt law) reproduce abundance trends. Instead, fit trends with age recover Galaxy. method enables one unprecedented accuracy first Gyrs, both (R<7-8kpc) and (R>9-10kpc) discs as sampled solar vicinity. show that,...
Galaxy mergers are believed to trigger strong starbursts. This is well assessed by observations in the local Universe. However efficiency of this mechanism has poorly been tested so far for high redshift, actively star forming, galaxies. We present a suite pc-resolution hydrodynamical numerical simulations compare formation process along merging sequence and low z galaxies, varying gas mass fraction between two models. show that, same orbit, high-redshift gas-rich less efficient than...
The Evaluating Nilotinib Efficacy and Safety in Clinical Trials as First-Line Treatment (ENEST1st) study included 1089 patients with newly diagnosed chronic myeloid leukemia phase. rate of deep molecular response (MR4 (BCR-ABL1⩽0.01% on the International Scale or undetectable BCR-ABL1 ⩾10 000 ABL1 transcripts)) at 18 months was evaluated primary end point, responses monitored by European Outcome Study network standardized laboratories. This analysis conducted after all had completed 24...
One of the challenges related to stellar bars is accurately determine length bar in a disc galaxy. In literature, wide variety methods have been employed measure extent bar. However, systematic study on determining robustness and accuracy different estimators still beyond our grasp. Here, we investigate correlation (if any) between measurement while using an N -body model barred galaxy, where evolves self-consistently presence live dark matter halo. We temporal evolution length, (involving...
We investigate the properties of a clump-cluster galaxy at redshift 1.57. In optical observations, morphology this is dominated by eight star-forming clumps, and its photometric are typical most chain galaxies. Its complex asymmetrical has led to suggestion that system group merger several initially separate proto-galaxies. performed Hα integral field spectroscopy using SINFONI on VLT UT4. These observations reveal large-scale velocity gradient throughout system, but with large local...
Using a large suite of galaxies with variety concentrations and metallicity gradients, we study the evolution non-dissipative ("dry") equal mass mergers. Our purpose in generating these simulations is to explore how gradient dry mergers depends on structure gradients involved merger. Specifically, would like answer: Could lead as observed elliptical local Universe? Do always flattening initial (i.e., pre-merger) gradient? From this modeling, conclude that: The ratio remnant galaxy slopes...
The Canada-France Imaging Survey (CFIS) will map the northern high Galactic latitude sky in $u$-band ("CFIS-u", 10,000$\, {\rm deg^2}$) and $r$-band ("CFIS-r", 5,000$\, deg^2}$), enabling a host of stand-alone science investigations, providing some ground-based data necessary for photometric redshift determination Euclid mission. In this first contribution we present component survey, describe observational strategy, discuss highlight results, based on approximately one third final area. We...