Publications (52)
HST/STIS observations of sdBV stars: testing diffusion and pulsation theory
S. J. O'Toole, U. Heber, P. Chayer +3
We present the initial results of an abundance analysis of echelle UV spectra of 5 hot subdwarf B (sdB) stars. These stars have been identified as core helium burning objects on th…
Observational Asteroseismology of Hot Subdwarf Stars with the Mont4K/Kuiper Combination at the Steward Observatory Mount Bigelow Station
G. Fontaine, E. M. Green, S. Charpinet +5
In the last few years, we have carried out several extensive observational campaigns on pulsating hot subdwarf stars using the Mont4K CCD camera attached to the 1.55 m Kuiper Teles…
Heavy-metal enrichment of intermediate He-sdOB stars: the pulsators Feige 46 and LS IV -14 116 revisited
M. Dorsch, M. Latour, U. Heber +3
Hot subdwarf stars of types O and B represent a poorly understood phase in the evolution of low-mass stars. Many subdwarfs show rich oscillations and are among the most chemically…
Abundance analysis of targets for the COROT / MONS asteroseimology missions I. Semi-automatic abundance analysis of the gamma Dor star HD 49434
H. Bruntt, C. Catala, R. Garrido +7
One of the goals of the ground-based support program for the COROT and MONS/Roemer satellite missions is to select and characterise suitable target stars for the part of the missio…
First Kepler results on compact pulsators V: Slowly pulsating subdwarf B stars in short-period binaries
S. D. Kawaler, M. D. Reed, R. H. Ãstensen +15
The survey phase of the Kepler Mission includes a number of hot subdwarf B (sdB) stars to search for nonradial pulsations. We present our analysis of two sdB stars that are found t…
The Arizona-Montréal spectroscopic survey of hot subluminous stars
M. Latour, E. M. Green, M. Dorsch +6
Hot subdwarf B (sdB) and O (sdO) type stars are evolved helium-burning objects that lost their hydrogen envelope before the helium flash when their progenitors were close to the ti…
Short-period pulsating hot-subdwarf stars observed by TESS II. Northern ecliptic hemisphere
A. S. Baran, S. Charpinet, R. H. Ãstensen +5
We present results of a continuation of our Transiting Exoplanet Survey Satellite (TESS) search for short-period pulsations in compact stellar objects observed during Years 2 and 4…
Abundance analysis of targets for the COROT / MONS asteroseismology missions II. Abundance analysis of the COROT main targets
H. Bruntt, I. F. Bikmaev, C. Catala +13
One of the goals of the ground-based support program for the COROT and Roemer satellite missions is to characterize suitable target stars for the part of the missions dedicated to…
EPIC 228782059: Asteroseismology of what could be the coolest pulsating helium-atmosphere white dwarf (DBV) known?
R. M. Duan, W. Zong, J. -N. Fu +5
We present analysis of a new pulsating helium-atmosphere (DB) white dwarf, EPIC~228782059, discovered from 55.1~days of {\em K2} photometry. The long duration, high quality light c…
Orbital properties of an unusually low-mass sdB star in a close binary system with a white dwarf
R. Silvotti, R. H. Ãstensen, S. Bloemen +17
We have used 605 days of photometric data from the Kepler spacecraft to study KIC 6614501, a close binary system with an orbital period of 0.15749747(25) days (3.779939 hours), tha…
First Kepler results on compact pulsators II: KIC 010139564, a new pulsating subdwarf B (V361 Hya) star with an additional low-frequency mode
Steven D. Kawaler, M. D. Reed, A. C. Quint +13
We present the discovery of nonradial pulsations in a hot subdwarf B star based on 30.5 days of nearly continuous time-series photometry using the \emph{Kepler} spacecraft. KIC 010…
Dilution of accreted planetary matter in hot DA white dwarfs according to their mass
M. Deal, S. Vauclair, S. Charpinet +1
A large proportion of observed white dwarfs (WDs) show evidence of debris disks, remnants of the former planetary systems, and/or signatures of heavy elements in their atmospheres,…
A transit survey to search for planets around hot subdwarfs: I. methods and performance tests on light curves from Kepler, K2, TESS, and CHEOPS
V. Van Grootel, F. J. Pozuelos, A. Thuillier +79
Context. Hot subdwarfs experienced strong mass loss on the Red Giant Branch (RGB) and are now hot and small He-burning objects. Aims. In this project we aim to perform a transit su…
The potential of asteroseismology for probing the core chemical stratification in white dwarf stars
N. Giammichele, S. Charpinet, P. Brassard +2
Context. The details of the C/O core structure in white dwarf stars has mostly remained inaccessible to the technique of asteroseismology, despite several attempts carried out in t…
Inter-comparison of the g-, f- and p-modes calculated using different oscillation codes for a given stellar model
A. Moya, J. Christensen-Dalsgaard, S. Charpinet +9
In order to make astroseismology a powerful tool to explore stellar interiors, different numerical codes should give the same oscillation frequencies for the same input physics. Th…
2006 Whole Earth Telescope Observations of GD358: A New Look at the Prototype DBV
J. L. Provencal, M. H. Montgomery, A. Kanaan +53
We report on the analysis of 436.1 hrs of nearly continuous high-speed photometry on the pulsating DB white dwarf GD358 acquired with the Whole Earth Telescope (WET) during the 200…
The theoretical pulsation spectra of hot B subdwarfs. Static and evolutionary STELUM models
N. Guyot, V. Van Grootel, S. Charpinet +3
Context. The Kepler and TESS space missions have revealed the rich gravity (g-)mode pulsation spectra of many hot subdwarf B (sdB) stars in detail. These spectra exhibit complex be…
Asteroseismology of alpha Cen A. Evidence of rotational splitting
M. Bazot, F. Bouchy, H. Kjeldsen +3
Asteroseismology provides a unique tool for studying stellar interiors. Recently p modes have been detected on the bright solar-like star alpha Cen A thanks to high-precision radia…
Structural Parameters of the Hot Pulsating B Subdwarf PG 1219+534 from Asteroseismology
S. Charpinet, G. Fontaine, P. Brassard +2
We have carried out a detailed asteroseismic analysis of PG 1219+534. Our analysis leads to the identification of the (k,l) indices of nine periods observed in the star PG 1219+534…
Evidence of Resonant Mode Coupling in the Pulsating DB White Dwarf Star KIC 08626021
W. Zong, S. Charpinet, G. Vauclair
The Kepler spacecraft provides new opportunities to search for long term frequency and amplitude modulations of oscillation modes in pulsating stars. We ana- lyzed nearly two years…
First Kepler results on compact pulsators III: Subdwarf B stars with V1093~Her and hybrid (DW~Lyn) type pulsations
M. D. Reed, S. D. Kawaler, R. H. Ostensen +12
We present the discovery of nonradial pulsations in five hot subdwarf B (sdB) stars based on 27 days of nearly continuous time-series photometry using the Kepler spacecraft. We fin…
First Kepler results on compact pulsators I. Survey target selection and the first pulsators
R. H. Ãstensen, R. Silvotti, S. Charpinet +25
We present results from the first two quarters of a survey to search for pulsations in compact stellar objects with the Kepler spacecraft. The survey sample and the various methods…
Toward High Precision Seismic Studies of White Dwarf Stars: Parametrization of the Core and Tests of Accuracy
N. Giammichele, S. Charpinet, G. Fontaine +1
We present a prescription for parametrizing the chemical profile in the core of white dwarfs in the light of the recent discovery that pulsation modes may sometimes be deeply confi…
Seismic signature of a magnetic field in the Doradus star KIC 2309579
S. Ihallaine, J. Ballot, F. Lignières +4
Internal magnetic fields have recently been detected and measured in the radiative core of red giant stars using asteroseismology. Being one of red giant stars progenitors and exhi…
Amplitude and frequency variations of oscillation modes in the pulsating DB white dwarf star KIC~08626021: The likely signature of nonlinear resonant mode coupling
W. Zong, S. Charpinet, G. Vauclair +2
Aims. We use the Kepler data accumulated on the pulsating DB white dwarf KIC 08626021 to explore in detail the stability of its oscillation modes, searching in particular for evide…
First Kepler results on compact pulsators VI. Targets in the final half of the survey phase
R. H. Ãstensen, R. Silvotti, S. Charpinet +29
We present results from the final six months of a survey to search for pulsations in white dwarfs and hot subdwarf stars with the Kepler spacecraft. Spectroscopic observations are…
The exoplanet-host star iota Horologii: an evaporated member of the primordial Hyades cluster
S. Vauclair, M. Laymand, F. Bouchy +4
We show that the exoplanet-host star iota Horologii, alias HD17051, which belongs to the so-called Hyades stream, was formed within the primordial Hyades stellar cluster and has ev…
Kepler observations of the beaming binary KPD 1946+4340
S. Bloemen, T. R. Marsh, R. H. Ãstensen +24
The Kepler Mission has acquired 33.5d of continuous one-minute photometry of KPD 1946+4340, a short-period binary system that consists of an sdB and a white dwarf. In the light cur…
Preparing the COROT space mission: incidence and characterisation of pulsation in the Lower Instability Strip
E. Poretti, R. Garrido, P. J. Amado +24
By pursuing the goal to find new variables in the COROT field-of-view we characterised a sample of stars located in the lower part of the instability strip. Our sample is composed…
Toward a systematic cartography of the chemical stratification inside white dwarfs from deep asteroseismic probing of ZZ Ceti stars
S. Charpinet, N. Giammichele, P. Brassard +5
DA-type white dwarfs account for 80% of all white dwarfs and represent, for most of them, the ultimate outcome of the typical evolution of low-to-intermediate mass stars. Their int…
TESS first look at evolved compact pulsators : Discovery and asteroseismic probing of the g-mode hot B subdwarf pulsator EC 21494-7018
S. Charpinet, P. Brassard, G. Fontaine +29
We present the discovery and asteroseismic analysis of a new g-mode hot B subdwarf (sdB) pulsator, EC 21494-7018 (TIC 278659026), monitored in TESS first sector using 120-second ca…
High-resolution spectropolarimetric observations of hot subdwarfs
P. Petit, V. Van Grootel, S. Bagnulo +3
We report on high-resolution spectropolarimetric observations of the hot subdwarf stars HD 76431 and Feige 66, using the ESPaDOnS echelle spectropolarimeter at CFHT. We compute cro…
The PLATO 2.0 Mission
H. Rauer, C. Catala, C. Aerts +159
PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it…
Short-period pulsating hot-subdwarf stars observed by TESS I. Southern ecliptic hemisphere
A. S. Baran, V. Van Grootel, R. H. Ostensen +7
We present results of a Transiting Exoplanet Survey Satellite (TESS) search for short-period pulsations in compact stellar objects observed in years 1 and 3 of the TESS mission, du…
Seismic evidence for non-synchronization in two close sdB+dM binaries from Kepler photometry
Herbert Pablo, Steven D. Kawaler, M. D. Reed +16
We report on extended photometry of two pulsating sdB stars in close binaries. For both cases, we use rotational splitting of the pulsation frequencies to show that the sdB compone…
Gender and Precarity in Astronomy
N. A. Webb, C. Bot, S. Charpinet +6
Following the survey Well-being in astrophysics that was sent out in March 2021, to establish how astrophysics researchers, primarily in France, experience their career, some of th…
Precise Modeling of the Exoplanet Host Star and CoRoT Main Target HD 52265
M. E. Escobar, S. Théado S. Vauclair, J. Ballot +8
This paper presents a detailed and precise study of the characteristics of the Exoplanet Host Star and CoRoT main target HD 52265, as derived from asteroseismic studies. The result…
First Kepler results on compact pulsators VIII: Mode identifications via period spacings in mode pulsating Subdwarf B stars
M. D. Reed, A. Baran, A. C. Quint +13
We investigate the possibility of nearly-equally spaced periods in 13 hot subdwarf B (sdB) stars observed with the Kepler spacecraft and one observed with CoRoT. Asymptotic limits…
TESS first look at evolved compact pulsators: asteroseismology of the pulsating helium-atmosphere white dwarf TIC 257459955
Keaton J. Bell, Alejandro H. Córsico, Agnès Bischoff-Kim +10
Pulsation frequencies reveal the interior structures of white dwarf stars, shedding light on the properties of these compact objects that represent the final evolutionary stage of…
Asteroseismic cartography of hydrogen-deficient white dwarfs
N. Giammichele, S. Charpinet, G. Fontaine +4
We present the results of the asteroseismic analysis of the hydrogen-deficient white dwarf PG 0112+104 from the -2 field. Our seismic procedure using the forward method bas…
First Kepler results on compact pulsators VII. Pulsating subdwarf B stars detected in the second half of the survey phase
A. S. Baran, S. D. Kawaler, M. D. Reed +10
We present five new pulsating subdwarf B (sdB) stars discovered by the Kepler spacecraft during the asteroseismology survey phase. We perform time-series analysis on the nearly con…
TESS first look at evolved compact pulsators: Known ZZ Ceti stars of the southern ecliptic hemisphere as seen by TESS
Zs. Bognár, S. D. Kawaler, K. J. Bell +13
Context. We present our findings on 18 formerly known ZZ Ceti stars observed by the TESS space telescope in 120s cadence mode during the survey observation of the southern ecliptic…
white dwarfs within 40 pc I: spectroscopic observations of new candidates
P. -E. Tremblay, M. A. Hollands, N. P. Gentile Fusillo +30
We present a spectroscopic survey of 230 white dwarf candidates within 40 pc of the Sun from the William Herschel Telescope and Gran Telescopio Canarias. All candidates were select…
Observations and asteroseismological analysis of the rapid subdwarf B pulsator EC 09582-1137
S. K. Randall, V. Van Grootel, G. Fontaine +2
We made photometric and spectroscopic observations of the rapidly pulsating subdwarf B star EC 09582-1137 with the aim of determining the target's fundamental structural parameters…
Searching for new white dwarf pulsators for TESS observations at Konkoly Observatory
Zs. Bognár, Cs. Kalup, Ã. Sódor +2
We present the results of our survey searching for new white dwarf pulsators for observations by the TESS space telescope. We collected photometric time-series data on 14 white dwa…
GAUDI: a preparatory archive for the COROT mission
E. Solano, C. Catala, R. Garrido +34
The GAUDI database (Ground-based Asteroseismology Uniform Database Interface, http://sdc.laeff.esa.es/gaudi/) is a preparatory archive for the COROT (COnvection, ROtation and plane…
Asteroseismology of the ZZ Ceti star HS 0507+0434B
J. -N. Fu, N. Dolez, G. Vauclair +14
The pulsating DA white dwarfs (ZZ Ceti stars) are -mode non-radial pulsators. Asteroseismology provides strong constraints on their global parameters and internal structure. Sin…
Observations and asteroseismic analysis of the rapidly pulsating hot B subdwarf PG 0911+456
S. K. Randall, E. M. Green, V. Van Grootel +11
The principal aim of this project is to determine the structural parameters of the rapidly pulsating subdwarf B star PG 0911+456 from asteroseismology. Our work forms part of an on…
Well-being in French Astrophysics
N. A. Webb, C. Bot, S. Charpinet +8
It has become clear that early career astrophysics researchers (doctoral researchers, post-docs, etc) have a very diverse appreciation of their career, with some declaring it the b…
Precision asteroseismology of the pulsating white dwarf GD 1212 using a two-wheel-controlled Kepler spacecraft
J. J. Hermes, S. Charpinet, Thomas Barclay +14
We present a preliminary analysis of the cool pulsating white dwarf GD 1212, enabled by more than 11.5 days of space-based photometry obtained during an engineering test of the two…
Kepler detection of a new extreme planetary system orbiting the subdwarf-B pulsator KIC10001893
R. Silvotti, S. Charpinet, E. Green +7
KIC10001893 is one out of 19 subdwarf-B (sdB) pulsators observed by the Kepler spacecraft in its primary mission. In addition to tens of pulsation frequencies in the g-mode domain,…
Gravity-Mode Instabilities in Models of Post-Extreme Horizontal Branch Stars: Another Class of Pulsating Stars?
S. Charpinet, G. Fontaine, P. Brassard +1
We present new results of a stability analysis of realistic models of post-extreme horizontal branch stars. We find that g-mode instabilities develop in some of these models as a r…