A photometric study of the hot exoplanet WASP-19b

Context: When the planet transits its host star, it is possible to measure the planetary radius and (with radial velocity data) the planet mass. For the study of planetary atmospheres, it is essential to obtain transit and occultation measurements at multiple wavelengths. Aims: We aim to characterize the transiting hot Jupiter WASP-19b by deriving accurate and precise planetary parameters from a dedicated observing campaign of transits and occultations. Methods: We have obtained a total of 14 transit lightcurves in the r'-Gunn, IC, z'-Gunn and I+z' filters and 10 occultation lightcurves in z'-Gunn using EulerCam on the Euler-Swiss telescope and TRAPPIST. We have also obtained one lightcurve through the narrow-band NB1190 filter of HAWK-I on the VLT measuring an occultation at 1.19 micron. We have performed a global MCMC analysis of all new data together with some archive data in order to refine the planetary parameters and measure the occultation depths in z'-band and at 1.19 micron. Results: We measure a planetary radius of R_p = 1.376 (+/-0.046) R_j, a planetary mass of M_p = 1.165 (+/-0.068) M_j, and find a very low eccentricity of e = 0.0077 (+/-0.0068), compatible with a circular orbit. We have detected the z'-band occultation at 3 sigma significance and measure it to be dF_z'= 352 (+/-116) ppm, more than a factor of 2 smaller than previously published. The occultation at 1.19 micron is only marginally constrained at dF_1190 = 1711 (+/-745) ppm. Conclusions: We have shown that the detection of occultations in the visible is within reach even for 1m class telescopes if a considerable number of individual events are observed. Our results suggest an oxygen-dominated atmosphere of WASP-19b, making the planet an interesting test case for oxygen-rich planets without temperature inversion.Comment: Published in Astronomy & Astrophysics. 11 pages, 11 figures, 4 table

Astérosismologie des étoiles pré-séquence principale de masse intermédiaire (étoiles Ae de Herbig) par une approche spectroscopique de haute-résolution

Les étoiles Ae/Be de Herbig sont des étoiles jeunes (pré-séquence principale, PMS), de masse intermédiaire (2-10 Msun) présentant des signes d'une activité intense et de forts vents stellaires, dont l'origine n'est pas expliquée par les théories actuelles d'évolution stellaire. Des travaux observationnels tendent à indiquer que la source énergétique de cette activité serait d'origine interne. Il est donc essentiel d'extraire des informations sur la structure interne des étoiles de Herbig par le biais de l'astérosismologie, c'est-à-dire l'observation, l'analyse et la modélisation des fréquences et des modes d'oscillations des étoiles pulsantes. Une telle étude implique de caractériser et de contraindre la bande d'instabilité PMS théorique, représentant la zone du diagramme Hertzsprung-Russell dans laquelle ces étoiles pulsent, et qui est traversée par les étoiles Ae de Herbig pendant leur trajet évolutif. Dans ce but, je me suis, d'une part, concentrée sur le cas de l'étoile prototype HD 104237, en étudiant ses paramètres photosphériques fondamentaux, indispensables à une modélisation astérosismique ultérieure. L'étude des variations de profil de raies photosphériques de cette étoile a confirmé la présence d'oscillations multi-périodiques et a permis de détecter des pulsations non-radiales. Une identification de certains modes de pulsation a été réalisée. La modélisation des pulsations de cette étoile dans le cadre adiabatique a fourni des pistes intéressantes à explorer quant au mécanisme d'excitation des modes de pulsation observés. L'étude a ensuite été étendue à 4 autres étoiles de Herbig observées avec HARPS (ESO), et leur analyse préliminaire est présentée.Herbig Ae/Be stars are pre-main sequence stars of intermediate mass (2-10 Msun) showing signs of intense activity and strong winds. The origin of their tremendous activity is still not understood in the frame of current theoretical evolutionary models. As of today, growing observational evidences tend to indicate that the energy needed to produce this activity might be of internal origin, but no definite answer has been provided. Solving this still open question is a major concern for testing young stellar evolutionary theory. This could be done by constraining the internal structure of these objects using asteroseismic techniques, i.e. the observation, analysis and modeling of stellar pulsation frequencies and modes. Such a study implies to caracterise and to constrain the theoretical PMS instability strip that Herbig stars cross for a significant fraction of their evolution to the main sequence. Having this aim, I studied first the prototype Ae Herbig star HD 104237. I carried a study of its photospheric fundamental parameters, which was necessary for a further asteroseismic modelling. The analysis of the photospheric line profile variations of this star confirmed the presence of multi-periodic oscillations and enabled the detection of several non-radial pulsations. I could identify some of the pulsation modes and modelled these pulsations in an adiabatic framework. This has supplied interesting leads about the excitation mechanism of the observed pulsations of HD 104237. I then extended my study to 4 others Herbig stars that were observed with HARPS (ESO) in the course of my thesis. Preliminary results of the asteroseismic analysis are presented in my manuscript

Rôles des récepteurs à l'hormone thyroïdienne, TRa1 et p43, dans le contrôle de la prolifération des cellules de Sertoli chez la souris

Des changements dans le statut thyroïdien altèrent les fonctions testiculaires, impliquant, entre autre, le récepteur à la T3, TRa1. Lorsqu un récepteur dominant-négatif de TRa1 (TRa AMI) est spécifiquement introduit dans les cellules de Sertoli (lignée TRa AMI-SC), on observe une augmentation significative de l index de prolifération des cellules de Sertoli à 3 jpp, induisant une augmentation de la densité de ces cellules et du poids testiculaire chez l adulte. Ce phénotype est corrélé à une modification de l expression de gènes clés du cycle cellulaire dont Cdk4, JunD et c-myc. Lorsque le récepteur TRa AMI est introduit également dans les cellules de Leydig (lignée TRa AMI-Aro), la sécrétion de testostérone est augmentée. Enfin, nous montrons l implication de l isoforme mitochondriale p43 du récepteur TRa1, dans ce contrôle T3- dépendant et autonome de la prolifération des cellules de Sertoli suggérant l existence d un crosstalk entre génome nucléaire et mitochondrial dans cette régulation par la T3.Changes in the thyroid status altered testicular functions, involving thyroid hormone receptors, among them, TRa1 is implied The expression of a TRa1 dominant-negative receptor (TRa AMI) specifically in Sertoli cells (TRa AMI-SC mice) leads to a significant increase in Sertoli cell proliferation at 3 dpp, inducing an increase in Sertoli cell density, testis weight and testicular spermatic reserve at adulthood. This phenotype is correlated with changes in cell cycle gene expression like Cdk4, JunD and c-myc. When TRa AMI is also expressed in Leydig cells (TRa AMI-Aro mice), it induces an increase in testosterone levels. Finally, we demonstrate that the mitochondrial p43 receptor is involved in this T3-dependant control of Sertoli cell proliferation, suggesting the existence of a crosstalk between nuclear and mitochondrial genomes.TOURS-Bibl.électronique (372610011) / SudocSudocFranceF

Développement participatif d'un outil technologique d'aide à la supervision en EHPAD ou de l'importance d'une remontée des besoins des futurs utilisateurs pour une conception plus pertinente

National audienceLe projet e-monitor'age vise à développer un système d'aide à la supervision des résidents en EHPAD (Etablissement d'Hébergement pour Personnes Agées Dépendantes). L'originalité de l'approche est que ce système (multicapteur et logiciel) est développé via une conception participative, c'est-à-dire main dans la main avec les personnels afin de répondre aux vrais besoins des " end users " et que son acceptabilité par ces personnels soit la meilleure possible

The rapid rotation and complex magnetic field geometry of Vega

The recent discovery of a weak surface magnetic field on the normal intermediate-mass star Vega raises the question of the origin of this magnetism in a class of stars that was not known to host magnetic fields. We aim to confirm the field detection and provide additional observational constraints about the field characteristics, by modelling the magnetic geometry of the star and by investigating the seasonal variability of the reconstructed field. We analyse a total of 799 circularly-polarized spectra collected with the NARVAL and ESPaDOnS spectropolarimeters during 2008 and 2009. We employ a cross-correlation procedure to compute, from each spectrum, a mean polarized line profile with a signal-to-noise ratio of about 20,000. The technique of Zeeman-Doppler Imaging is then used to determine the rotation period of the star and reconstruct the large-scale magnetic geometry of Vega at two different epochs. We confirm the detection of circularly polarized signatures in the mean line profiles. The amplitude of the signatures is larger when spectral lines of higher magnetic sensitivity are selected for the analysis, as expected for a signal of magnetic origin. The short-term evolution of polarized signatures is consistent with a rotational period of 0.732 \pm 0.008 d. The reconstructed magnetic topology unveils a magnetic region of radial field orientation, closely concentrated around the rotation pole. This polar feature is accompanied by a small number of magnetic patches at lower latitudes. No significant variability in the field structure is observed over a time span of one year. The repeated observation of a weak photospheric magnetic field on Vega suggests that a previously unknown type of magnetic stars exists in the intermediate-mass domain. Vega may well be the first confirmed member of a much larger, as yet unexplored, class of weakly-magnetic stars.Comment: Accepted by Astronomy & Astrophysics. Abstract shortened to respect the arXiv limit of 1920 character

Spectroscopic monitoring of the Herbig Ae star HD 104237. II. Non-radial pulsations, mode analysis and fundamental stellar parameters

Herbig Ae/Be stars are intermediate-mass pre-main sequence (PMS) stars showing signs of intense activity and strong stellar winds, whose origin is not yet understood in the frame of current theoretical models of stellar evolution for young stars. The evolutionary tracks of the earlier Herbig Ae stars cross a recently discovered PMS instability strip. Many of these stars exhibit pulsations of delta Scuti type. HD 104237 is a well-known pulsating Herbig Ae star. In this article, we reinvestigated an extensive high-resolution quasi-continuous spectroscopic data set in order to search for very faint indications of non-radial pulsations in the line profile. To do this, we worked on dynamical spectra of equivalent photospheric (LSD) profiles of HD 104237. A 2D Fourier analysis (F2D) was performed of the entire profile and the temporal variation of the central depth of the line was studied with the time-series analysis tools Period04 and SigSpec. We present a mode identification corresponding to the detected dominant frequency. We perform a new accurate determination of the fundamental stellar parameters in view of a forthcoming asteroseismic modeling. Following the previous studies on this star, our analysis of the dynamical spectrum of recentered LSD profiles corresponding to the 22nd -25th of April 1999 nights spectra has confirmed the presence of multiple oscillation modes of low-degree l in HD 104237 and led to the first direct detection of a non-radial pulsation mode in this star: the dominant mode F1 was identified by the Fourier 2D method having a degree l value comprised between 1 and 2, the symmetry of the pattern variation indicating an azimuthal order of +1 or -1. The detailed study of the fundamental stellar parameters has provided a Teff, log g and iron abundance of 8550 +/- 150K, 3.9 +/- 0.3 and -4.38 +/- 0.19 (i.e. [Fe/H]=+0.16 +/- 0.19), respectively

CoRoT\,102699796, the first metal-poor Herbig Ae pulsator: a hybrid δ\delta Sct-γ\gamma Dor variable?

We 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 following stellar parameters: spectral type F1V, T$_{\rm eff}$=7000$\pm$200 K, log(g)=$3.8\pm0.4$, [M/H]=$-1.1\pm0.2$, $v$sin$i$=$50\pm5$ km/s, L/L$_{\odot}$=21$^{+21}_{-11}$. Thus, for the first time we report the existence of a metal poor, intermediate-mass PMS pulsating star. Ground-based and satellite data are used to derive the spectral energy distribution of CoRoT\,102699796 extending from the optical to mid-infrared wavelengths. The SED shows a significant IR excess at wavelengths greater than $\sim5 \mu$. We conclude that CoRoT\,102699796 is a young Herbig Ae (F1Ve) star with a transitional disk, likely associated to the HII region [FT96]213.1-2.2. The pulsation frequencies have been interpreted in the light of the non-radial pulsation theory, using the LOSC code in conjunction with static and rotational evolutionary tracks. A minimization algorithm was used to find the best-fit model with M=1.84 M$_{\odot}$, T$_{\rm eff}$=6900 K which imply an isochronal age of t$\sim$2.5 Myr. This result is based on the interpretation of the detected frequencies as $g$-modes of low-moderate $n$-value. To our knowledge, this is the first time that such modes are identified in a intermediate-mass PMS pulsating star. Since CoRoT\,102699796 lies in the region of the HR diagram where the $\delta$ Sct and $\gamma$ Dor instability strips intersect, we argue that the observed pulsation characteristics are intermediate between these classes of variables, i.e. CoRoT\,102699796 is likely the first PMS hybrid $\gamma$ Dor-$\delta$ Sct pulsator ever studied.Comment: 13 pages, 7 figures. Accepted for publication in Monthly Notices of the RA

The TRAPPIST survey of southern transiting planets. I. Thirty eclipses of the ultra-short period planet WASP-43 b

We present twenty-three transit light curves and seven occultation light curves for the ultra-short period planet WASP-43 b, in addition to eight new measurements of the radial velocity of the star. Thanks to this extensive data set, we improve significantly the parameters of the system. Notably, the largely improved precision on the stellar density (2.41+-0.08 rho_sun) combined with constraining the age to be younger than a Hubble time allows us to break the degeneracy of the stellar solution mentioned in the discovery paper. The resulting stellar mass and size are 0.717+-0.025 M_sun and 0.667+-0.011 R_sun. Our deduced physical parameters for the planet are 2.034+-0.052 M_jup and 1.036+-0.019 R_jup. Taking into account its level of irradiation, the high density of the planet favors an old age and a massive core. Our deduced orbital eccentricity, 0.0035(-0.0025,+0.0060), is consistent with a fully circularized orbit. We detect the emission of the planet at 2.09 microns at better than 11-sigma, the deduced occultation depth being 1560+-140 ppm. Our detection of the occultation at 1.19 microns is marginal (790+-320 ppm) and more observations are needed to confirm it. We place a 3-sigma upper limit of 850 ppm on the depth of the occultation at ~0.9 microns. Together, these results strongly favor a poor redistribution of the heat to the night-side of the planet, and marginally favor a model with no day-side temperature inversion.Comment: 14 pages, 6 tables, 11 figures. Accepted for publication in A&

First evidence of pulsations in Vega? Results of today's most extensive spectroscopic search

The impact of rapid rotation on stellar evolution theory remains poorly understood as of today. Vega is a special object in this context as spectroscopic and interferometric studies have shown that it is a rapid rotator seen nearly pole one, a rare orientation particularly interesting for seismic studies. In this paper we present a first systematic search for pulsations in Vega. The goal of the present work is to detect for the first time pulsations in a rapidly rotating star seen nearly pole-on. Vega was monitored in quasi-continuous high-resolution echelle spectroscopy. A total of 4478 spectra were obtained within 3 individual runs in 2008, 2009 and 2010 at high resolution. This data set should represent the most extensive high S/N, high resolution quasi-continuous survey obtained on Vega as of today. Equivalent photospheric absorption profiles were calculated for the stellar spectrum, but also for the telluric lines acting as a radial velocity reference. Residual velocities were analysed and periodic low amplitude variations, potentially indicative of stellar pulsations, detected. All three data sets revealed the presence of residual periodic variations: 5.32 and 9.19 c/d, (A approx 6 m/s) in 2008, 12.71 and 13.25 c/d, (A approx 8 m/s) in 2009 and 5.42 and 10.82 c/d, (A approx 3-4 m/s) in 2010. A Lomb-Scargle periodogram of each velocity bin of the equivalent profile was performed for the 2010 run, not showing the presence of any higher order nrp mode. It is too early to conclude that the variations are due to stellar pulsations, and a confirmation of the detection with a highly stable spectrograph is a necessary next step. If pulsations are confirmed, their very small amplitudes show that the star would belong to a category of very "quiet" pulsators

Three newly discovered sub-Jupiter-mass planets: WASP-69b and WASP-84b transit active K dwarfs and WASP-70Ab transits the evolved primary of a G4+K3 binary

We report the discovery of the transiting exoplanets WASP-69b, WASP-70Ab and WASP-84b, each of which orbits a bright star (V ∼ 10). WASP-69b is a bloated Saturn-mass planet (0.26 MJup, 1.06 RJup) in a 3.868-d period around an active, ∼1-Gyr, mid-K dwarf. ROSAT detected X-rays 60±27 arcsec from WASP-69. If the star is the source then the planet could be undergoing mass-loss at a rate of ∼1012 g s−1. This is one to two orders of magnitude higher than the evaporation rate estimated for HD 209458b and HD 189733b, both of which have exhibited anomalously large Lyman α absorption during transit. WASP-70Ab is a sub-Jupiter-mass planet (0.59 MJup, 1.16 RJup) in a 3.713-d orbit around the primary of a spatially resolved, 9–10-Gyr, G4+K3 binary, with a separation of 3.3 arcsec (≥800 au). WASP-84b is a sub-Jupiter-mass planet (0.69 MJup, 0.94 RJup) in an 8.523-d orbit around an active, ∼1-Gyr, early-K dwarf. Of the transiting planets discovered from the ground to date, WASP-84b has the third-longest period. For the active stars WASP-69 and WASP-84, we pre-whitened the radial velocities using a low-order harmonic series. We found that this reduced the residual scatter more than did the oft-used method of pre-whitening with a fit between residual radial velocity and bisector span. The system parameters were essentially unaffected by pre-whitening