Results for "C. Neiner"

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Making a Be star: the role of rotation and pulsationsNov 10 2013The Be phenomenon, i.e. the ejection of matter from Be stars into a circumstellar disk, has been a long lasting mystery. In the last few years, the CoRoT satellite brought clear evidence that Be outbursts are directly correlated to pulsations and rapid ... More
A search for Vega-like fields in OB starsOct 10 2014Very weak magnetic fields (with a longitudinal component below 1 Gauss) have recently been discovered in the A star Vega as well as in a few Am stars. According to fossil field scenarios, such weak fields should also exist in more massive stars. In the ... More
XMM-Newton observations of MR Vel/RX J0925.7-4758Jul 01 2002We report on XMM-Newton observations of the galactic supersoft X-ray source RX J0925.7-4758. The RGS spectrum exhibits a wealth of spectral features from iron and oxygen. XMM-Newton data confirm the finding of previous Chandra HETGS/MEG observations that ... More
The BinaMIcS project: binarity and magnetismNov 11 2013We present the BinaMIcS project, its goals and the first BinaMIcS spectropolarimetric observations obtained with Narval at TBL and ESPaDOnS at CFHT: dedicated time-series for targeted hot and cool close double-line spectroscopic (SB2) binaries and a survey ... More
Preparing and correcting extracted BRITE observationsOct 18 2016Extracted BRITE lightcurves must be carefully prepared and corrected for instrumental effects before a scientific analysis can be performed. Therefore, we have created a suite of Python routines to prepare and correct the lightcurves, which is publicly ... More
The magnetic field of the hot spectroscopic binary HD5550Oct 07 2015HD5550 is a spectroscopic binary composed of two A stars observed with Narval at TBL in the frame of the BinaMIcS (Binarity and Magnetic Interactions in various classes of Stars) Large Program. One component of the system is found to be an Ap star with ... More
Discovery of a magnetic field in the B pulsating system HD 1976Feb 13 2014The presence of a magnetic field can have a strong impact on the evolution of a binary star. However, only a dozen of magnetic OB binaries are known as of today and available to study this effect, including very few magnetic pulsating spectroscopic OB ... More
MOBSTER - II. Identification of rotationally variable A stars observed with \emph{TESS} in Sectors 1 to 4May 21 2019Recently, high-precision optical 2~min cadence light curves obtained with \emph{TESS} for targets located in the mission's defined first four sectors have been released. The majority of these high-cadence and high-precision measurements currently span ... More
Abundance analysis of prime B-type targets for asteroseismology I. Nitrogen excess in slowly-rotating beta Cephei starsJul 12 2006We present the results of a detailed NLTE abundance study of nine beta Cephei stars, all of them being prime targets for theoretical modelling: gamma Peg, delta Cet, nu Eri, beta CMa, xi1 CMa, V836 Cen, V2052 Oph, beta Cep and DD (12) Lac. The following ... More
Stellar physics with high-resolution UV spectropolarimetryMar 15 2019Current burning issues in stellar physics, for both hot and cool stars, concern their magnetism. In hot stars, stable magnetic fields of fossil origin impact their stellar structure and circumstellar environment, with a likely major role in stellar evolution. ... More
gamma Peg: testing Vega-like magnetic fields in B starsDec 12 2013gam Peg is a bright B pulsator showing both p and g modes of beta Cep and SPB types. It has also been claimed to be a magnetic star by some authors while others do not detect a magnetic field. We aimed at checking for the presence of a field, characterise ... More
The magnetic field of evolved hot starsNov 13 2018About 10% of hot stars host a fossil magnetic field on the pre-main sequence and main sequence. However, the first magnetic evolved hot stars have been discovered only recently. An observing program has been set up to find more such objects. This will ... More
The "Binarity and Magnetic Interactions in various classes of Stars" (BinaMIcS) projectOct 07 2015The "Binarity and Magnetic Interactions in various classes of stars" (BinaMIcS) project is based on two large programs of spectropolarimetric observations with ESPaDOnS at CFHT and Narval at TBL. Three samples of spectroscopic binaries with two spectra ... More
Magnetic fields of Be stars: preliminary results from a hybrid analysis of the MiMeS sampleNov 22 2014In the context of the MiMeS survey of magnetism in massive stars, 85 classical Be stars were observed in circular polarization with the aim of detecting magnetic fields at their surfaces. No direct evidence of such fields is found, in contrast to the ... More
Combining magnetic and seismic studies to constrain processes in massive starsNov 10 2013The presence of pulsations influences the local parameters at the surface of massive stars and thus it modifies the Zeeman magnetic signatures. Therefore it makes the characterisation of a magnetic field in pulsating stars more difficult and the characterisation ... More
Magnetic field topology of the unique chemically peculiar star CU VirginisApr 09 2014The late-B magnetic chemically peculiar star CU Vir is one of the fastest rotators among the intermediate-mass stars with strong fossil magnetic fields. It shows a prominent rotational modulation of the spectral energy distribution and absorption line ... More
Be star outbursts: transport of angular momentum by wavesNov 11 2013The Be phenomenon, that is the ejection of matter from Be stars into a circumstellar disk, has been a long lasting mystery. In the last few years, the CoRoT (Convection, Rotation and planetary Transits) satellite brought clear evidence that Be outbursts ... More
A Volume Limited Survey of mCP Stars Within 100pc II: Rotational and Magnetic PropertiesNov 14 2018Various surveys focusing on the magnetic properties of intermediate-mass main sequence (MS) stars have been previously carried out. One particularly puzzling outcome of these surveys is the identification of a dichotomy between the strong ($\gtrsim100\,{\rm ... More
UVMag: a UV and optical spectropolarimeter for stellar physicsNov 10 2013UVMag is a space project currently under R&D study. It consists in a medium-size telescope equipped with a spectropolarimeter to observe in the UV and optical wavelength domains simultaneously. Its first goal is to obtain time series of selected magnetic ... More
Attempts to measure the magnetic field of the pulsating B star $ν$ EridaniMar 13 2006We report on attempts to measure the magnetic field of the pulsating B star $\nu$ Eridani with the Musicos spectropolarimeter attached to the 2m telescope at the Pic du Midi, France. This object is one of the most extensively studied stars for pulsation ... More
A Volume-Limited Survey of mCP Stars Within 100pc I: Fundamental Parameters and Chemical AbundancesNov 14 2018We present the first results of a volume-limited survey of main sequence (MS) magnetic chemically peculiar (mCP) stars. The sample consists of all identified intermediate-mass MS stars (mCP and non-mCP) within a heliocentric distance of $100\,{\rm pc}$ ... More
Magnetic OB[A] Stars with TESS: probing their Evolutionary and Rotational properties (MOBSTER) - I. First-light observations of known magnetic B and A starsApr 25 2019In this paper we introduce the MOBSTER collaboration and lay out its scientific goals. We present first results based on the analysis of nineteen previously known magnetic O, B and A stars observed in 2-minute cadence in sectors 1 and 2 of the Transiting ... More
Massive stars with Pollux on LUVOIRNov 13 2018Many open questions remain about massive stars, for example about their evolution, their wind, and their maximum mass at formation. These issues could be ideally adressed by the Pollux UV spectropolarimeter onboard LUVOIR. Here we present examples of ... More
The magnetic field of $ζ$ Ori AAug 01 2014Magnetic fields play a significant role in the evolution of massive stars. About 7% of massive stars are found to be magnetic at a level detectable with current instrumentation and only a few magnetic O stars are known. Detecting magnetic field in O stars ... More
The dramatic change of the fossil magnetic field of HD 190073: evidence of the birth of the convective core in a Herbig star ?Jan 09 2013In the context of the ESPaDOnS and Narval spectropolarimetric surveys of Herbig Ae/Be stars, we discovered and then monitored the magnetic field of HD 190073 over more than four years, from 2004 to 2009. Our observations all displayed similar Zeeman signatures ... More
The magnetic field of the double-lined spectroscopic binary system HD 5550Jan 28 2016(Abridged) In the framework of the BinaMicS project, we have begun a study of the magnetic properties of a sample of intermediate-mass and massive short-period binary systems, as a function of binarity properties. We report in this paper the characterisation ... More
The magnetic field of zeta Orionis ASep 09 2015Zeta Ori A is a hot star claimed to host a weak magnetic field, but no clear magnetic detection was obtained so far. In addition, it was recently shown to be a binary system composed of a O9.5I supergiant and a B1IV star. We aim at verifying the presence ... More
K2 space photometry reveals rotational modulation and stellar pulsations in chemically peculiar A and B starsMay 04 2018May 11 2018The physics of magnetic hot stars and how a large-scale magnetic field affects their interior properties is largely unknown. Few studies have combined high-quality observations and modelling of magnetic pulsating stars, known as magneto-asteroseismology, ... More
Period spacings of gravity modes in rapidly rotating magnetic stars I. Axisymmetric fossil field with poloidal and toroidal componentsMar 13 2019Context. Stellar magnetic fields are one of the candidates often invoked to explain the missing transport of angular momentum observed in the models of stellar interiors. However, the properties of an internal magnetic field and the consequences of its ... More
Period spacings of gravity modes in rapidly rotating magnetic stars I. Axisymmetric fossil field with poloidal and toroidal componentsMar 13 2019May 15 2019Context. Stellar magnetic fields are one of the candidates often invoked to explain the missing transport of angular momentum observed in the models of stellar interiors. However, the properties of an internal magnetic field and the consequences of its ... More
Studying the photometric and spectroscopic variability of the magnetic hot supergiant $ζ$ Orionis AaApr 03 2017Massive stars play a significant role in the chemical and dynamical evolution of galaxies. However, much of their variability, particularly during their evolved supergiant stage, is poorly understood. To understand the variability of evolved massive stars ... More
The origin of magnetic fields in hot starsFeb 01 2015Observations of stable mainly dipolar magnetic fields at the surface of ~7% of single hot stars indicate that these fields are of fossil origin, i.e. they descend from the seed field in the molecular clouds from which the stars were formed. Recent results ... More
Search for magnetic fields in particle-accelerating colliding-wind binariesDec 17 2014Some colliding-wind massive binaries, called particle-accelerating colliding-wind binaries (PACWB), exhibit synchrotron radio emission, which is assumed to be generated by a stellar magnetic field. However, no measurement of magnetic fields in these stars ... More
Magnetic field topology of the cool, active, short-period binary system $σ^2$ Coronae BorealisFeb 03 2018The goal of this work is to study the cool, active binary star $\sigma^2$ CrB, focussing on its magnetic field. We used Stokes $IV$ data from the twin spectropolarimeters Narval at the TBL and ESPaDOnS at the CFHT. The least-squares deconvolution multi-line ... More
Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB star $ζ$ CassiopeiaeJan 18 2016Aims. The main-sequence B-type star $\zeta$ Cassiopeiae is known as a N-rich star with a magnetic field discovered with the Musicos spectropolarimeter. We model the magnetic field of the star by means of 82 new spectropolarimetric observations of higher ... More
An Observational Evaluation of Magnetic Confinement in the Winds of BA SupergiantsNov 20 2013Magnetic wind confinement has been proposed as one explanation for the complex wind structures of supergiant stars of spectral types B and A. Observational investigation of this hypothesis was undertaken using high-resolution ({\lambda}/{\Delta}{\lambda} ... More
Amplitude variations of the CoRoT Be star 102719279Oct 10 2010The Be star 102719279 is an interesting target observed with CoRoT during two runs, giving us the possibility to study the stability of the detected frequencies and to search for any correlation with outburts, as it was recently found in the Be star HD ... More
Testing magnetically confined wind shock models for Beta Cep using XMM-Newton and Chandra phase-resolved X-ray observationsJun 13 2008(abridged) We have performed a set of phase-resolved X-ray observations of the magnetic B star Beta Cep, for which theoretical models predict the presence of a confined wind emitting X-rays from stationary shocks. We obtained four observations spaced ... More
Understanding the photometric variability of ζ Ori AaOct 18 2016We studied the variability of the magnetic O-type supergiant $\zeta$ Ori Aa using multi-colour BRITE photometry. We confirmed the known rotation frequency $f_{\rm rot} = 0.15 \pm 0.02$ c/d, and detected some of its higher harmonics, of which $4f_{\rm ... More
The Magnetism in Massive Stars project: first HARPSpol discoveriesNov 05 2012In the framework of the Magnetism in Massive Stars (MiMeS) project, a HARPSpol Large Program at the 3.6m-ESO telescope has recently started to collect high-resolution spectropolarimetric data of a large number of Southern massive OB stars in the field ... More
Discovery of a magnetic field in the CoRoT hybrid B-type pulsator HD 43317Aug 21 2013Aug 22 2013A promising way of testing the impact of a magnetic field on internal mixing (core overshooting, internal rotation) in main-sequence B-type stars is to perform asteroseismic studies of a sample of magnetic pulsators. The CoRoT satellite revealed that ... More
Roadmap on the theoretical work of BinaMIcSNov 11 2013Nov 12 2013We review the different theoretical challenges concerning magnetism in interacting binary or multiple stars that will be studied in the BinaMIcS (Binarity and Magnetic Interactions in various classes of Stars) project during the corresponding spectropolarimetric ... More
Diverse Variability of O and B Stars Revealed from 2-minute Cadence Light Curves in Sectors 1 and 2 of the TESS Mission: Selection of an Asteroseismic SampleJan 22 2019Jan 24 2019Uncertainties in stellar structure and evolution theory are largest for stars undergoing core convection on the main sequence. A powerful way to calibrate the free parameters used in the theory of stellar interiors is asteroseismology, which provides ... More
Forward seismic modelling of the pulsating magnetic B-type star HD 43317May 02 2018May 31 2018The large-scale magnetic fields detected at the surface of about 10% of hot stars extend into the stellar interior, where they may alter the structure. Deep inner regions of stars are only observable using asteroseismology. Here, we investigated the pulsating ... More
Magnetic characterization and variability study of the magnetic SPB star o LupAug 16 2018Thanks to large dedicated surveys, large-scale magnetic fields have been detected for about 10% of early-type stars. We aim to precisely characterize the large-scale magnetic field of the magnetic component of the wide binary $o$ Lup, by using high-resolution ... More
Detection of magnetic fields in chemically peculiar stars observed with the K2 space missionMay 02 2018We report the results of an observational study aimed at searching for magnetic pulsating hot stars suitable for magneto-asteroseismology. A sample of sixteen chemically peculiar stars was selected and analysed using both high-resolution spectropolarimetry ... More
The role of Active Galactic Nuclei in galaxy evolution: insights from space ultraviolet spectropolarimetryMar 13 2019This Astro2020 white paper summarizes the unknowns of active galactic nuclei (AGN) physics that could be unveiled thanks to a new, space-born, ultraviolet spectropolarimeter. The unique capabilities of high energy polarimetry would help us to understand ... More
Study of KIC 8561221 observed by Kepler: an early red giant showing depressed dipolar modesNov 27 2013The continuous high-precision photometric observations provided by the CoRoT and Kepler space missions have allowed us to better understand the structure and dynamics of red giants using asteroseismic techniques. A small fraction of these stars shows ... More
Probing the structure and evolution of active galactic nuclei with the ultraviolet polarimeter POLLUX aboard LUVOIRSep 26 2018The ultraviolet (UV) polarization spectrum of nearby active galactic nuclei (AGN) is poorly known. The Wisconsin Ultraviolet Photo-Polarimeter Experiment and a handful of instruments on board the Hubble Space Telescope were able to probe the near- and ... More
Asteroseismology and spectropolarimetry: opening new windows on the internal dynamics of massive starsAug 19 2014In this article, we show how asteroseismology and spectropolarimetry allow to probe dynamical processes in massive star interiors. First, we give a summary of the state-of-the-art. Second, we recall the MHD mechanisms that take place in massive stars. ... More
Stochastic excitation of gravity waves in rapidly rotating massive starsAug 18 2014Stochastic gravity waves have been recently detected and characterised in stars thanks to space asteroseismology and they may play an important role in the evolution of stellar angular momentum. In this context, the observational study of the CoRoT hot ... More
First discovery of a magnetic field in a main sequence delta Scuti star: the Kepler star HD188774Aug 28 2015The Kepler space mission provided a wealth of {\delta} Sct-{\gamma} Dor hybrid candidates. While some may be genuine hybrids, others might be misclassified due to the presence of a binary companion or to rotational modulation caused by magnetism and related ... More
BD-19 5044L: discovery of a short-period SB2 system with a magnetic Bp primary in the open cluster IC 4725Jan 24 2017Until recently almost nothing was known about the evolution of magnetic fields found in upper main sequence Ap/Bp stars during their long main sequence lifetime. We are thus studying magnetic Ap/Bp stars in open clusters in order to obtain observational ... More
Spitzer/IRAC view of Sh 2-284: Searching for evidence of triggered star formation in an isolated region in the outer Milky WayJul 07 2009Using Spitzer/IRAC observations of a region to be observed by the CoRoT satellite, we have unraveled a new complex star-forming region at low metallicity in the outer Galaxy. We perform a study of S284 in order to outline the chain of events in this star-forming ... More
An infrared diagnostic for magnetism in hot starsMay 07 2015Magnetospheric observational proxies are used for indirect detection of magnetic fields in hot stars in the X-ray, UV, optical, and radio wavelength ranges. To determine the viability of infrared (IR) hydrogen recombination lines as a magnetic diagnostic ... More
Spectrographs with holographic gratings on freeform surfaces: design approach and application for the LUVOIR missionMay 23 2018In the present paper we demonstrate the approach to use a holographic grating on a freeform surface for advanced spectrographs design. On the example POLLUX spectropolarimeter medium-UV channel we chow that such a grating can operate as a cross-disperser ... More
Kepler's first view of O-star variability: K2 data of five O stars in Campaign 0 as a proof-of-concept for O-star asteroseismologyJul 11 2015We present high-precision photometric light curves of five O-type stars observed with the refurbished {\it Kepler\/} satellite during its Campaign 0. For one of the stars, we also assembled high-resolution ground-based spectroscopy with the {\sc hermes} ... More
Multiperiodic pulsations in the Be stars NW Ser and V1446 AqlJul 06 2007Aims: We present accurate photometric time series of two Be stars: NW Ser and V1446 Aql. Both stars were observed at the Observatorio de Sierra Nevada (Granada) in July 2003 with an automatic four-channel Str\"omgren photometer. We also present a preliminary ... More
HD 41641: A classical $δ$ Sct-type pulsator with chemical signatures of an Ap starFeb 15 2016Feb 24 2016Among the known groups of pulsating stars, $\delta$ Sct stars are one of the least understood. Theoretical models do not predict the oscillation frequencies that observations reveal. Complete asteroseismic studies are necessary to improve these models ... More
Magnetic fields in early-type starsJun 12 2015For several decades we have been cognizant of the presence of magnetic fields in early-type stars, but our understanding of their magnetic properties has recently (over the last decade) expanded due to the new generation of high-resolution spectropolarimeters ... More
CoRoT\,102699796, the first metal-poor Herbig Ae pulsator: a hybrid $δ$ Sct-$γ$ Dor variable?Jun 02 2011We present the analysis of the time series observations of CoRoT\,102699796 obtained by the CoRoT satellite that show the presence of five independent oscillation frequencies in the range 3.6-5 c/d. Using spectra acquired with FLAMES@VLT, we derive the ... More
Detection of ultra-weak magnetic fields in Am stars: beta UMa and theta LeoJan 08 2016An extremely weak circularly polarized signature was recently discovered in spectral lines of the chemically peculiar Am star Sirius A. A weak surface magnetic field was proposed to account for the observed polarized signal, but the shape of the phase-averaged ... More
First results from the LIFE project: discovery of two magnetic hot evolved starsDec 20 2017We present the initial results of the Large Impact of magnetic Fields on the Evolution of hot stars (LIFE) project. The focus of this project is the search for magnetic fields in evolved OBA giants and supergiants with visual magnitudes between 4 and ... More
The MiMeS Survey of Magnetism in Massive Stars: CNO surface abundances of Galactic O starsNov 17 2014The evolution of massive stars is still partly unconstrained. Mass, metallicity, mass loss and rotation are the main drivers of stellar evolution. Binarity and magnetic field may also significantly affect the fate of massive stars. Our goal is to investigate ... More
On the incidence of magnetic fields in slowly-pulsating B, Beta Cephei and B-type emission line starsJun 08 2009We have obtained 40 high-resolution circular spectropolarimetric measurements of 12 slowly-pulsating B (SPB) stars, 8 Beta Cephei stars and two Be stars with the ESPaDOnS and NARVAL spectropolarimeters. The aim of these observations is to evaluate recent ... More
The magnetic field of the B3V star 16 PegasiDec 25 2008The Slowly Pulsating B3V star 16 Pegasi was discovered by Hubrig (2006) to be magnetic, based on low-resolution spectropolarimetric observations with FORS1 at the VLT. We have confirmed the presence of a magnetic field with new measurements with the spectropolarimeters ... More
Search for pulsation among suspected A-type binaries and the new multiperiodic Delta Scuti star HD217860May 31 2007We have explored a sample of suspected A-type binaries in a systematic way, both spectroscopically and photometrically. Due to their location in the H-R diagram, indications of pulsation and/or chemical peculiarities among these suspected binary (or multiple) ... More
Critical evaluation of magnetic field detections reported for pulsating B-type stars in the light of ESPaDOnS, Narval and reanalyzed FORS1/2 observationsFeb 10 2012Feb 15 2012Recent spectropolarimetric studies of 7 SPB and $\beta$ Cep stars have suggested that photospheric magnetic fields are more common in B-type pulsators than in the general population of B stars, suggesting a significant connection between magnetic and ... More
Revisiting the Rigidly Rotating Magnetosphere model for sigma Ori E. I. Observations and Data AnalysisSep 01 2011We have obtained 18 new high-resolution spectropolarimetric observations of the B2Vp star sigma Ori E with both the Narval and ESPaDOnS spectropolarimeters. The aim of these observations is to test, with modern data, the assumptions of the Rigidly Rotating ... More
The Magnetic Early B-type Stars I: Magnetometry and RotationJan 09 2018The rotational and magnetic properties of many magnetic hot stars are poorly characterized, therefore the MiMeS and BinaMIcS collaborations have collected extensive high-dispersion spectropolarimetric datasets of these targets. We present longitudinal ... More
Discovery of new magnetic early-B stars within the MiMeS HARPSpol surveyApr 22 2014To understand the origin of the magnetic fields in massive stars as well as their impact on stellar internal structure, evolution, and circumstellar environment, within the MiMeS project, we searched for magnetic objects among a large sample of massive ... More
The Magnetic Early B-type Stars II: stellar atmospheric parameters in the era of GaiaFeb 07 2019Atmospheric parameters determined via spectral modelling are unavailable for many of the known magnetic early B-type stars. We utilized high-resolution spectra together with NLTE models to measure effective temperatures $T_{\rm eff}$ and surface gravities ... More
Searching for Weak or Complex Magnetic Fields in Polarized Spectra of RigelSep 13 2010Seventy-eight high-resolution Stokes V, Q and U spectra of the B8Iae supergiant Rigel were obtained with the ESPaDOnS spectropolarimeter at CFHT and its clone NARVAL at TBL in the context of the Magnetism in Massive Stars (MiMeS) Large Program, in order ... More
CoRoT photometry and high-resolution spectroscopy of the interacting eclipsing binary AU MonSep 08 2009Analyses of very accurate CoRoT space photometry, past Johnson V photoelectric photometry and high-resolution \'echelle spectra led to the determination of improved and consistent fundamental stellar properties of both components of AU Mon. We derived ... More
Impact of rotation on stochastic excitation of gravity and gravito-inertial waves in starsMar 25 2014Gravity waves (or their signatures) are detected in stars thanks to helio- and asteroseismology and they may play an important role in the evolution of stellar angular momentum. Moreover, the observational study of the CoRoT target HD51452 by Neiner and ... More
Discovery of a very weak magnetic field on the Am star AlhenaMar 21 2016Alhena ($\gamma$ Gem) was observed in the frame of the BRITE (BRIght Target Explorer) spectropolarimetric survey, which gathers high resolution, high signal-to-noise, high sensitivity, spectropolarimetric observations of all stars brighter than V=4 to ... More
A multisite photometric study of two unusual Beta Cep stars: the magnetic V2052 Oph and the massive rapid rotator V986 OphMay 29 2012We report a multisite photometric campaign for the Beta Cep stars V2052 Oph and V986 Oph. 670 hours of high-quality differential photoelectric Stromgren, Johnson and Geneva time-series photometry were obtained with eight telescopes on five continents ... More
Pulsation-driven mean zonal and meridional flows in rotating massive starsJul 08 2015Jan 04 2016Zonal and meridional axisymmetric flows can deeply impact the rotational and chemical evolution of stars. Therefore, momentum exchanges between waves propagating in stars, differential rotation, and meridional circulation must be carefully evaluated. ... More
POLLUX: a UV spectropolarimeter for the LUVOIR space telescope projectMay 23 2018The present paper describes the current baseline optical design of POLLUX, a high-resolution spectropolarimeter for the future LUVOIR mission. The instrument will operate in the ultraviolet (UV) domain from 90 to 390 nm in both spectropolarimetric and ... More
Angular momentum transport by stochastically excited oscillations in rapidly rotating massive starsApr 21 2014We estimate the amount of angular momentum transferred by the low-frequency oscillations detected in the rapidly rotating hot Be star HD 51452. Here, we assume that the oscillations detected are stochastically excited by convective motions in the convective ... More
Magnetic B stars observed with BRITE: Spots, magnetospheres, binarity, and pulsationsNov 09 2016Magnetic B-type stars exhibit photometric variability due to diverse causes, and consequently on a variety of timescales. In this paper we describe interpretation of BRITE photometry and related ground-based observations of 4 magnetic B-type systems: ... More
Discovery of a magnetic field in the O9 sub-giant star HD 57682 by the MiMeS CollaborationOct 01 2009We report the detection of a strong, organised magnetic field in the O9IV star HD 57682, using spectropolarimetric observations obtained with ESPaDOnS at the 3.6-m Canada-France-Hawaii Telescope within the context of the Magnetism in Massive Stars (MiMeS) ... More
The BinaMIcS project: understanding the origin of magnetic fields in massive stars through close binary systemsSep 03 2014It is now well established that a fraction of the massive (M>8 Msun) star population hosts strong, organised magnetic fields, most likely of fossil origin. The details of the generation and evolution of these fields are still poorly understood. The BinaMIcS ... More
Investigating the spectroscopic, magnetic and circumstellar variability of the O9 subgiant star HD 57682Jul 30 2012The O9IV star HD 57682, discovered to be magnetic within the context of the MiMeS survey in 2009, is one of only eight convincingly detected magnetic O-type stars. Among this select group, it stands out due to its sharp-lined photospheric spectrum. Since ... More
The MiMeS survey of magnetism in massive stars: Magnetic analysis of the O-type starsOct 25 2016We present the analysis performed on spectropolarimetric data of 97 O-type targets included in the framework of the MiMeS (Magnetism in Massive Stars) Survey. Mean Least-Squares Deconvolved Stokes I and V line profiles were extracted for each observation, ... More
The MiMeS Project: First ResultsDec 22 2008Massive stars are those stars with initial masses above about 8 times that of the sun, eventually leading to catastrophic explosions in the form of supernovae. These represent the most massive and luminous stellar component of the Universe, and are the ... More
The MiMeS Project: Magnetism in Massive StarsDec 22 2008Jan 03 2009The Magnetism in Massive Stars (MiMeS) Project is a consensus collaboration among the foremost international researchers of the physics of hot, massive stars, with the basic aim of understanding the origin, evolution and impact of magnetic fields in these ... More
Magnetic B stars observed with BRITE: Spots, magnetospheres, binarity, and pulsationsNov 09 2016Nov 18 2016Magnetic B-type stars exhibit photometric variability due to diverse causes, and consequently on a variety of timescales. In this paper we describe interpretation of BRITE photometry and related ground-based observations of 4 magnetic B-type systems: ... More
Magnetic field measurements and wind-line variability of OB-type starsAug 25 2010Context. The first magnetic fields in O- and B-type stars that do not belong to the Bp-star class, have been discovered. The cyclic UV wind-line variability, which has been observed in a significant fraction of early-type stars, is likely to be related ... More
The magnetic characteristics of Galactic OB stars from the MiMeS survey of magnetism in massive starsOct 15 2013The Magnetism in Massive Stars (MiMeS) project represents the largest systematic survey of stellar magnetism ever undertaken. Based on a sample of over 550 Galactic B and O-type stars, the MiMeS project has derived the basic characteristics of magnetism ... More
Investigating the origin of cyclical wind variability in hot, massive stars - I. On the dipolar magnetic field hypothesisJul 24 2014OB stars exhibit various types of spectral variability associated with wind structures, including the apparently ubiquitous discrete absorption components (DACs). These are proposed to be caused by either magnetic fields or non-radial pulsations (NRPs). ... More
UVMag: stellar formation, evolution, structure and environment with space UV and visible spectropolarimetryJul 10 2014Important insights into the formation, structure, evolution and environment of all types of stars can be obtained through the measurement of their winds and possible magnetospheres. However, this has hardly been done up to now mainly because of the lack ... More
Photometric and spectroscopic variability of the B5IIIe star HD 171219May 19 2017We analyzed the star HD 171219, one of the relatively bright Be stars observed in the seismo field of the CoRoT satellite, in order to determine its physical and pulsation characteristics. Classical Be stars are main-sequence objects of mainly B-type, ... More
Pre-Main Sequence stars in the star forming complex Sh 2-284Sep 02 2010Located at the galactic anticenter, Sh 2-284 is a HII region which harbors several young open clusters; Dolidze 25, a rare metal poor (Z~0.004) young cluster, is one of these. Given its association with Sh 2-284, it is reasonable to assume the low metallicity ... More
MOST Observations of sigma Ori E: Challenging the Centrifugal Breakout NarrativeApr 08 2013We present results from three weeks' photometric monitoring of the magnetic helium-strong star sigma Ori E using the MOST microsatellite. The star's light curve is dominated by twice-per-rotation eclipse-like dimmings arising when magnetospheric clouds ... More
BRITE photometry of the massive post-RLOF system HD149404Nov 08 2018HD149404 is an evolved non-eclipsing O-star binary that has previously undergone a Roche lobe overflow interaction. Understanding some key properties of the system requires a determination of the orbital inclination and of the dimensions of the components. ... More
The BRITE spectropolarimetric programNov 10 2016A high-resolution spectropolarimetric survey of all (573) stars brighter than magnitude V=4 has been undertaken with Narval at TBL, ESPaDOnS at CFHT, and HarpsPol at ESO, as a ground-based support to the BRITE constellation of nano-satellites in the framework ... More
Combining seismology and spectropolarimetry of hot starsJul 30 2014Asteroseismology and spectropolarimetry have allowed us to progress significantly in our understanding of the physics of hot stars over the last decade. It is now possible to combine these two techniques to learn even more information about hot stars ... More
Discovery of two new bright magnetic B stars: i Car and AtlasAug 27 2015The BRITE (BRIght Target Explorer) constellation of nano-satellites performs seismology of bright stars via high precision photometry. In this context, we initiated a high resolution, high signal-to-noise, high sensitivity, spectropolarimetric survey ... More
The surface nitrogen abundance of a massive star in relation to its oscillations, rotation, and magnetic fieldDec 15 2013We have composed a sample of 68 massive stars in our galaxy whose projected rotational velocity, effective temperature and gravity are available from high-precision spectroscopic measurements. The additional seven observed variables considered here are ... More