Pulsations in hot supergiants

Massive stars are the cosmic engines that shape and drive our Universe. Many issues such as their formation, their stability and the mass loss effects, are far from being completely understood. Recent ground-based and space observations have shown pulsations in massive MS and post-MS stars, such as acoustic and gravity modes excited by the κ-mechanism and even solar-like oscillations. Theoretical studies emphasized the presence of strange modes in massive models, and recent theoretical analyses have shown that hot supergiants can pulsate in oscillatory convective modes. We review the instability domains of massive stars as well as their excitation mechanisms and present the latest results

The PLATO 2.0 mission

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 addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 s readout cadence and 2 with 2.5 s candence) providing a wide field-of-view (2232 deg 2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2 %, 4-10 % and 10 % for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50 % of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0. The PLATO 2.0 catalogue allows us to e.g.: - complete our knowledge of planet diversity for low-mass objects, - correlate the planet mean density-orbital distance distribution with predictions from planet formation theories,- constrain the influence of planet migration and scattering on the architecture of multiple systems, and - specify how planet and system parameters change with host star characteristics, such as type, metallicity and age. The catalogue will allow us to study planets and planetary systems at different evolutionary phases. It will further provide a census for small, low-mass planets. This will serve to identify objects which retained their primordial hydrogen atmosphere and in general the typical characteristics of planets in such low-mass, low-density range. Planets detected by PLATO 2.0 will orbit bright stars and many of them will be targets for future atmosphere spectroscopy exploring their atmosphere. Furthermore, the mission has the potential to detect exomoons, planetary rings, binary and Trojan planets. The planetary science possible with PLATO 2.0 is complemented by its impact on stellar and galactic science via asteroseismology as well as light curves of all kinds of variable stars, together with observations of stellar clusters of different ages. This will allow us to improve stellar models and study stellar activity. A large number of well-known ages from red giant stars will probe the structure and evolution of our Galaxy. Asteroseismic ages of bright stars for different phases of stellar evolution allow calibrating stellar age-rotation relationships. Together with the results of ESA's Gaia mission, the results of PLATO 2.0 will provide a huge legacy to planetary, stellar and galactic science

Ecological succession, palaeoenvironmental change, and depositional sequences of Barremian-Aptian shallow-water carbonates in northern Oman

Barremian and Aptian shallow-water carbonate facies (uppermost Lekhwair, Kharaib and Shuaiba Formations) are described from outcrops in northern Oman. Based on facies analysis and bedding pattern, three orders of depositional sequences are defined (third to fifth order) and correlated between sections. Over the course of three third-order sequences, covering the Barremian to Lower Aptian, a third-order depositional pattern is documented that consists of a succession of three distinct faunal assemblages: discoidal orbitolinids and calcareous algae were deposited during early transgression; microbialites and microencrusters dominate the late transgressive to early highstand facies; and a rudist- and miliolid-dominated facies is typical of the highstand. This ecological succession was controlled largely by palaeoenvironmental changes, such as trophic level and clay influx, rather than sedimentological factors controlled by variations in accommodation space. Orbitolinid beds and carbonates formed by microbialites and microencrusters seem to be the shallow-water carbonate response to global changes affecting Late Barremian to Aptian palaeoclimate and palaeoceanography

CoRoT Measures Solar-Like Oscillations and Granulation in Stars Hotter Than the Sun

Oscillations of the Sun have been used to understand its interior structure. The extension of similar studies to more distant stars has raised many difficulties despite the strong efforts of the international community over the past decades. The CoRoT (Convection Rotation and Planetary Transits) satellite, launched in December 2006, has now measured oscillations and the stellar granulation signature in three main sequence stars that are noticeably hotter than the sun. The oscillation amplitudes are about 1.5 times as large as those in the Sun; the stellar granulation is up to three times as high. The stellar amplitudes are about 25% below the theoretic values, providing a measurement of the nonadiabaticity of the process ruling the oscillations in the outer layers of the stars

Assessment of renal function in clinical practice at the bedside of burn patients

International audienceWHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: * In burn patients it has been shown ([2]), that there is a correlation between the creatinine clearance (CL(CR)) and the clearance of inulin. * The CL(CR) has never been studied in burn patients who have normal serum creatinine. * The Robert, Kirkpatrick and sMDRD formulae have never been evaluated in burn patients. WHAT THIS STUDY ADDS: * Despite burn patients having normal serum creatinine concentrations, the study showed that there are large variations in CL(CR) which cannot be detected by single serum creatinine measurements, and which have important implications for drug therapy. * It showed that the formulae currently used to calculate creatinine clearance on the basis of serum creatinine are inadequate for use in burn patients, and they should be abandoned in favour of direct measurement from a 24 h urine collection. AIMS: The aim of this study was to evaluate whether the renal function of burn patients could be correctly assessed using a single serum creatinine measurement, within normal limits, and three prediction equations of glomerular filtration taking into account, serum creatinine, age, weight and sex. METHODS: This was a prospective study comprising 36 adult burn patients with a serum creatinine 140 ml(-1) min(-1) 1.73 m(-2)) was found in 13 patients younger than 40 years. Regression analysis, residual and Bland-Altman plots revealed that neither the Cockcroft-Gault, Robert, Kirkpatrick nor sMDRD equations were specific enough for the assessment of renal function. CONCLUSIONS: In burn patients with normal serum creatinine during the hypermetabolic phase, serum creatinine and creatine based predictive equations are imprecise in assessing renal function