Cholelithiasis leads to 80,000 cholecystectomies being performed every year in France, but its prevalence is still unknown. The aim of this study was to assess the prevalence and risk factors of ...cholelithiasis in a random population of 1027 women and 727 men over the age of 30 in a small town in the southeast of France. Detailed clinical history, dietary investigation, and gallbladder ultrasound were collected for each subject and assessed by univariate analysis. A regression model was used in the multivariate analysis to detect the relative risk of cholelithiasis. Cholelithiasis was found in 130 individuals (global prevalence 13.9%). The relative risk for lithiasis was higher in women compared to men (1.89). Age (P<0.0001) and body mass index (BMI) >25 (P = 0.013) were also significant risk factors. Neither pregnancy nor oral contraceptive use proved to be risk factors. Typical biliary colic pain was the only symptom significantly associated with cholelithiasis (P<0.0001). These results show that the prevalence of gallstones in France is similar to that in Denmark and Italy.
We present the concept of a novel facility dedicated to massively-multiplexed spectroscopy. The telescope has a very wide field Cassegrain focus optimised for fibre feeding. With a Field of View ...(FoV) of 2.5 degrees diameter and a 11.4m pupil, it will be the largest etendue telescope. The large focal plane can easily host up to 16.000 fibres. In addition, a gravity invariant focus for the central 10 arc-minutes is available to host a giant integral field unit (IFU). The 3 lenses corrector includes an ADC, and has good performance in the 360-1300 nm wavelength range. The top level science requirements were developed by a dedicated ESO working group, and one of the primary cases is high resolution spectroscopy of GAIA stars and, in general, how our Galaxy formed and evolves. The facility will therefore be equipped with both, high and low resolution spectrographs. We stress the importance of developing the telescope and instrument designs simultaneously. The most relevant R\&D aspect is also briefly discussed.
The VLT Unit telescope 4 will be equipped in 2013 with an Adaptive Optics (AO) Facility, replacing the current secondary mirror of the telescope with an adaptive one. The AO Facility will allow high ...order AO correction at all three telescope foci.
The Multi Unit Spectroscopic Explorer MUSE MUSE public web site: http://muse.univ-lyon1.fr is one of the second generation VLT instruments. MUSE is a wide-field optical integral field spectrograph ...operating in the visible wavelength range with improved spatial resolution. The MUSE Consortium consists of groups at Lyon (PI institute, CRAL), Gottingen (IAG), Potsdam (AIP), Leiden (NOVA), Toulouse (LATT), Zurich (ETH) and ESO. The project is currently in its final design phase. Manufacturing, assembly and integration will start after the Final Design Review which is foreseen for late 2008. The Preliminary acceptance in Europe is scheduled for mid 2011 and the instrument shall be in operation at Paranal in 2012.
Dietary risk factors have been implicated in the development of cholelithiasis. The aim of this study was to determine in a homogeneous French population whether a particular type of diet may be ...lithogenic. Seventy-six subjects over 30 years of age (26 men, 50 women) with cholelithiasis detected by ultrasound were selected from a population sample of 830 subjects by drawing lots using the polling list. These were matched by 76 control subjects without cholelithiasis randomly selected from the same population. Univariate analysis was significant for a high calorie diet >2500 kcal/day (OR = 3.62, P = 0.0065), a diet rich in carbohydrates with a consumption > or = 55 g/day (OR = 2.98, P = 0.0067), and a diet rich in total lipids (OR = 4.97, P = 0.023) or saturated fatty acids (OR = 3.06, P = 0.0146). An alcohol consumption equivalent to 20-40 g/day was protective (P = 0.018). Multivariate analysis confirmed these results. Our study suggests that a change in dietary habits by limiting excess calories, saturated fats and carbohydrates could reduce the incidence of cholelithiasis.
Aims. We report on ESPRESSO high-resolution transmission spectroscopic observations of two primary transits of the highly-irradiated, ultra-hot Jupiter-size planet WASP-76b. We investigate the ...presence of several key atomic and molecular features of interest that may reveal the atmospheric properties of the planet. Methods. We extracted two transmission spectra of WASP-76b with R approx 140,000 using a procedure that allowed us to process the full ESPRESSO wavelength range (3800-7880 A) simultaneously. We observed that at a high signal-to-noise ratio, the continuum of ESPRESSO spectra shows wiggles that are likely caused by an interference pattern outside the spectrograph. To search for the planetary features, we visually analysed the extracted transmission spectra and cross-correlated the observations against theoretical spectra of different atomic and molecular species. Results. The following atomic features are detected: Li I, Na I, Mg I, Ca II, Mn I, K I, and Fe I. All are detected with a confidence level between 9.2 sigma (Na I) and 2.8 sigma (Mg I). We did not detect the following species: Ti I, Cr I, Ni I, TiO, VO, and ZrO. We impose the following 1 sigma upper limits on their detectability: 60, 77, 122, 6, 8, and 8 ppm, respectively. Conclusions. We report the detection of Li I on WASP-76b for the first time. In addition, we found the presence of Na I and Fe I as previously reported in the literature. We show that the procedure employed in this work can detect features down to the level of ~ 0.1 % in the transmission spectrum and ~ 10 ppm by means of a cross-correlation method. We discuss the presence of neutral and singly ionised features in the atmosphere of WASP-76b.
We characterized the transiting planetary system orbiting the G2V star K2-38 using the new-generation echelle spectrograph ESPRESSO. We carried out a photometric analysis of the available K2 ...photometric light curve of this star to measure the radius of its two known planets. Using 43 ESPRESSO high-precision radial velocity measurements taken over the course of 8 months along with the 14 previously published HIRES RV measurements, we modeled the orbits of the two planets through a MCMC analysis, significantly improving their mass measurements. Using ESPRESSO spectra, we derived the stellar parameters, \(T_{\rm eff}\)=5731\(\pm\)66, \(\log g\)=4.38\(\pm\)0.11~dex, and \(Fe/H\)=0.26\(\pm\)0.05~dex, and thus the mass and radius of K2-38, \(M_{\star}\)=1.03 \(^{+0.04}_{-0.02}\)~M\(_{\oplus}\) and \(R_{\star}\)=1.06 \(^{+0.09}_{-0.06}\)~R\(_{\oplus}\). We determine new values for the planetary properties of both planets. We characterize K2-38b as a super-Earth with \(R_{\rm P}\)=1.54\(\pm\)0.14~R\(_{\rm \oplus}\) and \(M_{\rm p}\)=7.3\(^{+1.1}_{-1.0}\)~M\(_{\oplus}\), and K2-38c as a sub-Neptune with \(R_{\rm P}\)=2.29\(\pm\)0.26~R\(_{\rm \oplus}\) and \(M_{\rm p}\)=8.3\(^{+1.3}_{-1.3}\)~M\(_{\oplus}\). We derived a mean density of \(\rho_{\rm p}\)=11.0\(^{+4.1}_{-2.8}\)~g cm\(^{-3}\) for K2-38b and \(\rho_{\rm p}\)=3.8\(^{+1.8}_{-1.1}\)~g~cm\(^{-3}\) for K2-38c, confirming K2-38b as one of the densest planets known to date. The best description for the composition of K2-38b comes from an iron-rich Mercury-like model, while K2-38c is better described by a rocky model with a H2 envelope. The maximum collision stripping boundary shows how giant impacts could be the cause for the high density of K2-38b. The irradiation received by each planet places them on opposite sides of the radius valley. We find evidence of a long-period signal in the radial velocity time-series whose origin could be linked to a 0.25-3~M\(_{\rm J}\) planet or stellar activity.
ESPRESSO is the new high-resolution spectrograph of ESO's Very-Large Telescope (VLT). It was designed for ultra-high radial-velocity precision and extreme spectral fidelity with the aim of performing ...exoplanet research and fundamental astrophysical experiments with unprecedented precision and accuracy. It is able to observe with any of the four Unit Telescopes (UT) of the VLT at a spectral resolving power of 140,000 or 190,000 over the 378.2 to 788.7 nm wavelength range, or with all UTs together, turning the VLT into a 16-m diameter equivalent telescope in terms of collecting area, while still providing a resolving power of 70,000. We provide a general description of the ESPRESSO instrument, report on the actual on-sky performance, and present our Guaranteed-Time Observation (GTO) program with its first results. ESPRESSO was installed on the Paranal Observatory in fall 2017. Commissioning (on-sky testing) was conducted between December 2017 and September 2018. The instrument saw its official start of operations on October 1st, 2018, but improvements to the instrument and re-commissioning runs were conducted until July 2019. The measured overall optical throughput of ESPRESSO at 550 nm and a seeing of 0.65 arcsec exceeds the 10% mark under nominal astro-climatic conditions. We demonstrate a radial-velocity precision of better than 25 cm/s during one night and 50 cm/s over several months. These values being limited by photon noise and stellar jitter show that the performanceis compatible with an instrumental precision of 10 cm/s. No difference has been measured across the UTs neither in throughput nor RV precision. The combination of the large collecting telescope area with the efficiency and the exquisite spectral fidelity of ESPRESSO opens a new parameter space in RV measurements, the study of planetary atmospheres, fundamental constants, stellar characterisation and many other fields.
HAWK-I, the High Accuity Wide-field K-band Imager, will be a near-optimum camera for the VLT. The 7.5 arcminute square field is practically the largest IR field possible at Nasmyth while keeping ...reasonably uniform sensitivity in all bands. The mosaic of four 2k×2k detectors which fills this field has a pixel scale of 0.1 arcsec/pixel, which is sufficiently small to adequately sample the best seeing at Paranal, even with future ground layer adaptive optics correction. An all-reflective optical design gives very high throughput. The end result is an imager with the best possible performance, limited predominantly by the telescope design and atmospheric seeing conditions.
Spectra of composite systems (e.g., spectroscopic binaries) contain spatial information that can be retrieved by measuring the radial velocities (i.e., Doppler shifts) of the components in four ...observations with the slit rotated by 90 degrees in the sky. By using basic concepts of slit spectroscopy we show that the geometry of composite systems can be reliably retrieved by measuring only radial velocity differences taken with different slit angles. The spatial resolution is determined by the precision with which differential radial velocities can be measured. We use the UVES spectrograph at the VLT to observe the known spectroscopic binary star HD 188088 (HIP 97944), which has a maximum expected separation of 23 milli-arcseconds. We measure an astrometric signal in radial velocity of 276 \ms, which corresponds to a separation between the two components at the time of the observations of 18 \(\pm2\) milli-arcseconds. The stars were aligned east-west. We describe a simple optical device to simultaneously record pairs of spectra rotated by 180 degrees, thus reducing systematic effects. We compute and provide the function expressing the shift of the centroid of a seeing-limited image in the presence of a narrow slit.The proposed technique is simple to use and our test shows that it is amenable for deriving astrometry with milli-arcsecond accuracy or better, beyond the diffraction limit of the telescope. The technique can be further improved by using simple devices to simultaneously record the spectra with 180 degrees angles.With tachoastrometry, radial velocities and astrometric positions can be measured simultaneously for many double line system binaries in an easy way. The method is not limited to binary stars, but can be applied to any astrophysical configuration in which spectral lines are generated by separate (non-rotational symmetric) regions.
