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Concept

Méthode des vitesses radiales

Publications associées (29)

Gaia's brightest very metal-poor (VMP) stars Metallicity catalogue of a thousand VMP stars from Gaia's radial velocity spectrometer spectra

Nicolas Lawrence Etienne Longeard

Context. Gaia DR3 has offered the scientific community a remarkable dataset of approximately one million spectra acquired with the radial velocity spectrometer (RVS) in the calcium II triplet region, which is well suited to identify very metal-poor (VMP) s ...

Edp Sciences S A2024

CEERS: Diversity of Lyα Emitters during the Epoch of Reionization

Michaela Hirschmann

We analyze rest-frame ultraviolet to optical spectra of three z similar or equal to 7.47-7.75 galaxies whose Ly alpha emission lines were previously detected with Keck/MOSFIRE observations, using the JWST/NIRSpec observations from the Cosmic Evolution Earl ...

Iop Publishing Ltd2024

Intra-pin Reaction Rate Measurements in the CROCUS Experimental Reactor

Andreas Pautz, Vincent Pierre Lamirand, Mathieu Hursin, Oskari Ville Pakari, Thomas Jean-François Ligonnet, Tom Mager

In response to the need for validating high-fidelity deterministic neutronics solvers capable of providing pin-resolved neutron flux distributions, intra-pin reaction rates measurements were performed in the CROCUS experimental reactor. A specially designe ...

2024

HD 213258: A new rapidly oscillating, super slowly rotating, strongly magnetic Ap star in a spectroscopic binary

Pierre North

We report on HD 213258, an Ap star that we recently identified as presenting a unique combination of rare, remarkable properties. Our study of this star is based on ESPaDOnS Stokes I and V data obtained at seven epochs spanning a time interval slightly sho ...

EDP SCIENCES S A2023

Snowfall microphysics: a dual-frequency and Doppler spectral radar perspective

Anne-Claire Marie Billault--Roux

Snowfall is an essential component of the hydrological cycle, as it is involved in most precipitation on Earth, either directly as snow falling to the ground or indirectly as rain melted from snow. At the same time, the ice phase of clouds and precipitatio ...

EPFL2023

Gaia Data Release 3 Summary of the variability processing and analysis

Mária Süveges

Context. Gaia has been in operations since 2014, and two full data releases (DR) have been delivered so far: DR1 in 2016 and DR2 in 2018. The third Gaia data release expands from the early data release (EDR3) in 2020, which contained the five-parameter ast ...

EDP SCIENCES S A2023

The extended stellar halo' of the Ursa Minor dwarf galaxy

Pascale Jablonka

Stellar candidates in the Ursa Minor (UMi) dwarf galaxy have been found using a new Bayesian algorithm applied to Gaia EDR3 data. Five of these targets are located in the extreme outskirts of UMi, from similar to 5 to 12 elliptical half-light radii (r h), ...

OXFORD UNIV PRESS2023

The Pristine dwarf galaxy survey - IV. Probing the outskirts of the dwarf galaxy Bootes I

Pascale Jablonka, Nicolas Lawrence Etienne Longeard, Romain Ely Roland Lucchesi

We present a new spectroscopic study of the dwarf galaxy Bootes I (Boo I) with data from the Anglo-Australian Telescope and its AAOmega spectrograph together with the Two Degree Field multi-object system. We observed 36 high-probability Boo I stars selecte ...

OXFORD UNIV PRESS2022

The eta Aquilae System: Radial Velocities and Astrometry in Search of eta Aql B

Richard Irving Anderson

The classical Cepheid eta Aql was not included in past Leavitt Law work because of a presumed complicating orbit due to a known B9.8V companion. To determine the orbit of eta Aql B, we analyze a significant number of radial velocity (RV) measurements from ...

2022

The Pristine survey - XVII. The C-19 stream is dynamically hot and more extended than previously thought

Pascale Jablonka, Carmela Lardo

The C-19 stream is the most metal-poor stellar system ever discovered, with a mean metallicity [Fe/H] = -3.38 +/- 0.06. Its low metallicity dispersion (sigma([Fe/H]) < 0.18 at the 95 per cent confidence level) and variations in sodium abundances strongly s ...

OXFORD UNIV PRESS2022

Effects of the parallel flow shear on the ITG-driven turbulent transport in tokamak plasmas

Javier García Hernández, Yann Camenen, Samuele Mazzi

The impact of the parallel flow shear on the tokamak plasma stability and turbulent transport driven by the ion temperature gradient (ITG) modes is analyzed by means of local gyrokinetic numerical analyses. It is shown that the parallel flow shear increase ...

IOP Publishing Ltd2022

Numerical and experimental investigation of spiral-grooved gas journal bearings

Elia Iseli

Small-scale turbomachinery is increasingly used in carbon-free energy conversion systems, such as commercial or domestic scale heat pumps, fuels cells for transportation and waste heat recovery. The usage of aerodynamic bearings allows the design of compac ...

EPFL2022

The Pristine survey - XIV. Chemical analysis of two ultra-metal-poor stars

Pascale Jablonka, Carmela Lardo

Elemental abundances of the most metal-poor stars reflect the conditions in the early Galaxy and the properties of the first stars. We present a spectroscopic follow-up of two ultra-metal-poor stars ([Fe/H] < -4.0) identified by the survey Pristine: Pristi ...

OXFORD UNIV PRESS2021

The formation of the Milky Way halo and its dwarf satellites: A NLTE-1D abundance analysis. V. The Sextans galaxy

Pascale Jablonka

We present a homogeneous set of accurate atmospheric parameters for a sample of eleven very metal-poor (-3.32

OXFORD UNIV PRESS2021

Method and system for analysis of organic material by auto-cathodoluminescence

Hans Mattias Larsson, Marcin Stefan Zielinski

Analyzing isolated collagen gel samples of a rat-tail and bovine hide, we demonstrated in situ detection of spectrally deconvoluted auto-cathodoluminescence signatures of specific molecular content with precise spatial localization over a maximum field of ...

2020

The Pristine survey - X. A large population of low-metallicity stars permeates the Galactic disc

Pascale Jablonka, Pierre North, Nicolas Lawrence Etienne Longeard, Romain Ely Roland Lucchesi

The orbits of the least chemically enriched stars open a window on the formation of our Galaxy when it was still in its infancy. The common picture is that these low-metallicity stars are distributed as an isotropic, pressure-supported component since thes ...

OXFORD UNIV PRESS2020

The Gaia-ESO Survey: Spectroscopic-asteroseismic analysis of K2 stars in Gaia-ESO The K2 Galactic Caps Project

Carmela Lardo

Context. The extensive stellar spectroscopic datasets that are available for studies in Galactic Archeaology thanks to, for example, the Gaia-ESO Survey, now benefit from having a significant number of targets that overlap with asteroseismology projects su ...

EDP SCIENCES S A2020

The chemical evolution of the dwarf spheroidal galaxy Sextans

Pascale Jablonka, Carmela Lardo, Pierre North, Romain Ely Roland Lucchesi, Romaine Theler

We present our analysis of the FLAMES dataset targeting the central 25 ' region of the Sextans dwarf spheroidal galaxy (dSph). This dataset is the third major part of the high-resolution spectroscopic section of the ESO large program 171.B-0588(A) obtained ...

EDP SCIENCES S A2020

Barium and related stars, and their white-dwarf companions

Pierre North, Conrad Johnston, Shreeya Sushil Shetye

Barium (Ba) dwarfs and CH subgiants are the less evolved analogues of Ba and CH giants. They are F- to G-type main-sequence stars polluted with heavy elements by their binary companions when the companion was on the asymptotic giant branch (AGB). This comp ...

EDP SCIENCES S A2019

Tracing the formation of the Milky Way through ultra metal-poor stars

Pascale Jablonka, Nicolas Lawrence Etienne Longeard

We use Gaia DR2 astrometric and photometric data, published radial velocities and MESA models to infer distances, orbits, surface gravities, and effective temperatures for all ultra metal-poor stars ([Fe/H] < -4.0 dex) available in the literature. Assuming ...

OXFORD UNIV PRESS2019