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Pierre North

Cette personne a quitté l’EPFL

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Publications associées (31)

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Barium and related stars, and their white-dwarf companions

Shreeya Sushil Shetye, Pierre North, Conrad Johnston

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

Lithium in red giant stars: Constraining non-standard mixing with large surveys in the Gaia era

Pierre North

Context. Li is extensively known to be a good tracer of non-standard mixing processes occurring in stellar interiors. Aims. We present the results of a new large Li survey in red giant stars and combine it with surveys from the literature to probe the impa ...

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

What is the Milky Way outer halo made of? High resolution spectroscopy of distant red giants

Pascale Jablonka, Pierre North

In a framework where galaxies form hierarchically, extended stellar haloes are predicted to be an ubiquitous feature around Milky Way-like galaxies and to consist mainly of the shredded stellar component of smaller galactic systems. The type of accreted st ...

Edp Sciences S A2017

HD 60431, the CP2 star with the shortest rotational period Physical parameters and period analysis

Pierre North

Context. CP2 stars show periodic photometric, spectroscopic, and magnetic variations with the rotational period. They are generally slow rotators, with rotational periods exceeding half a day, except for the late B-type star HD 60431, which has an unusuall ...

EDP SCIENCES S A2022

Polarimetry of the Lyα envelope of the radio-quiet quasar SDSS J124020.91+145535.6

Frédéric Courbin, Pierre North

The radio quiet quasar SDSS J1240+1455 lies at a redshift of z = 3.11, is surrounded by a Ly alpha blob (LAB), and is absorbed by a proximate damped Ly alpha system. In order to better define the morphology of the blob and determine its emission mechanism, ...

Edp Sciences S A2024

Spectroscopy of extended Ly alpha envelopes around z=4.5 quasars

Frédéric Courbin, Pierre North, Alexander Patrick Eigenbrod

What are the frequency, shape, kinematics, and luminosity of Ly alpha envelopes surrounding radio-quiet quasars at high redshift, and is the luminosity of these envelopes related to that of the quasar or not? As a first step towards answering these questio ...

2012

Manganese in dwarf spheroidal galaxies

Pascale Jablonka, Pierre North

We provide manganese abundances (corrected for the effect of the hyperfine structure) for a large number of stars in the dwarf spheroidal galaxies Sculptor and Fornax, and for a smaller number in the Carina and Sextans dSph galaxies. Abundances had already ...

2012

Deep optical spectroscopy of extended Ly alpha emission around three radio-quiet z=4.5 quasars

Frédéric Courbin, Pierre North, Alexander Patrick Eigenbrod

We report the first results of a spectroscopic search for Ly alpha envelopes around three z similar to 4.5 radio-quiet quasars. Our observational strategy adopts the FORS2 spectrograph mounted to the UT1 of the Very Large Telescope (VLT) in the multi-slit ...

2008

Early chemical enrichment of the Milky Way dwarf satellites from high-resolution and NLTE analysis of VMP stars

Pascale Jablonka, Pierre North

We present the NLTE abundances of 10 chemical species in 65 very metal-poor stars in eight dSphs and the Milky Way halo. The classical dSphs Sculptor, Ursa Minor, Sextans, and Fornax reveal a similar plateau at [alpha/Fe] = 0.3 for each of Mg, Ca, and Ti, ...

CAMBRIDGE UNIV PRESS2019

Properties and nature of Be stars 30. Reliable physical properties of a semi-detached B9.5e+G8III binary BR CMi = HD 61273 compared to those of other well studied semi-detached emission-line binaries

Matthias Wolf, Pierre North

Reliable determination of the basic physical properties of hot emission-line binaries with Roche-lobe filling secondaries is important for developing the theory of mass exchange in binaries. It is a very hard task, however, which is complicated by the pres ...

EDP Sciences2015

New distance and depth estimates from observations of eclipsing binaries in the SMC

Pierre North, Romain Gauderon

A sample of 33 eclipsing binaries observed in a field of the SMC with FLAMES@VLT is presented. The radial velocity curves obtained, together with existing OGLE light curves, allowed the determination of all stellar and orbital parameters of these binary sy ...

Cambridge University Press2009

Spectroscopic Orbits Of Three Dwarf Barium Stars

Pierre North

Barium stars are thought to result from binary evolution in systems wide enough to allow the more massive component to reach the asymptotic giant branch and eventually become a CO white dwarf. While Ba stars were initially known only among giant or subgian ...

OBSERVATORY2020

CNONa and C-12/C-13 in giant stars of 10 open clusters

Pierre North, Romain Gauderon

Context. Evolved low-mass stars (0.8

2009

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

The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis II. Early chemical enrichment

Pascale Jablonka, Pierre North

We present the non-local thermodynamic equilibrium (NLTE) abundances of up to 10 chemical species in a sample of 59 very metal-poor (VMP, -4

Edp Sciences S A2017

MUSE- inspired view of the quasar Q2059-360, its Lyman alpha blob, and its neighborhood

Frédéric Courbin, Pierre North, Claudio Gorgoni

The radio-quiet quasar Q2059-360 at redshift z = 3 : 08 is known to be close to a small Lyman ff blob (LAB) and to be absorbed by a proximate damped Ly ff (PDLA) system. Here, we present the Multi Unit Spectroscopic Explorer (MUSE) integral field spectrosc ...

Edp Sciences S A2017

Improved parameters for the transiting planet HD 17156b: a high-density giant planet with a very eccentric orbit

Pierre North

We report high-precision transit photometry for the recently detected planet HD 17156b. Using these new data with previously published transit photometry and radial velocity measurements, we perform a combined analysis based on a Markov Chain Monte Carlo a ...

2008

The evolution of Ap stars

Pierre North

The many peculiarities of Ap stars (not only chemical ones, but also magnetic field and slow rotation) may vary during the main-sequence evolution of these stars. We review here briefly the evidences found in the last thirty years for such evolution, with ...

2008

VLT multi-object spectroscopy of 33 eclipsing binaries in the Small Magellanic Cloud New distance and depth of the SMC, and a record-breaking apsidal motion

Pierre North, Romain Gauderon

Aims. Our purpose is to provide reliable stellar parameters for a significant sample of eclipsing binaries, which are representative of a whole dwarf and metal-poor galaxy. We also aim at providing a new estimate of the mean distance to the SMC and of its ...

2010