Publications de Pierre North | EPFL Graph Search

Chattez avec Graph Search

Posez n’importe quelle question sur les cours, conférences, exercices, recherches, actualités, etc. de l’EPFL ou essayez les exemples de questions ci-dessous.

AVERTISSEMENT : Le chatbot Graph n'est pas programmé pour fournir des réponses explicites ou catégoriques à vos questions. Il transforme plutôt vos questions en demandes API qui sont distribuées aux différents services informatiques officiellement administrés par l'EPFL. Son but est uniquement de collecter et de recommander des références pertinentes à des contenus que vous pouvez explorer pour vous aider à répondre à vos questions.

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 ...

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 ...

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 ...

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 ...

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 ...

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, ...

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 ...

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 ...

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 ...

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, ...

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 ...

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 ...

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 ...

Context. Evolved low-mass stars (0.8

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 ...

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

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 ...

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 ...

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 ...

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 ...

Pierre North

Chattez avec Graph Search

Barium and related stars, and their white-dwarf companions

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

The chemical evolution of the dwarf spheroidal galaxy Sextans

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

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

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

Spectroscopy of extended Ly alpha envelopes around z=4.5 quasars

Manganese in dwarf spheroidal galaxies

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

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

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

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

Spectroscopic Orbits Of Three Dwarf Barium Stars

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

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

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

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

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

The evolution of Ap stars

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