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Solar analogues are important stars to study for understanding the properties of the Sun. Combined with seismic and spectroscopic analysis, evolutionary modelling becomes a powerful method to characterize stellar intrinsic parameters, such as mass, radius, metallicity and age. However, these characteristics, relevant for other aspects of astrophysics or exoplanetary system physics, for example, are difficult to obtain with high precision and/or accuracy. The goal of this study is to characterize the two solar analogues, HD 42618 and HD 43587, observed by CoRoT. In particular, we aim to infer their precise mass, radius and age, using evolutionary modelling constrained by spectroscopic, photometric and seismic analysis. These stars show evidence of being older than the Sun but with a relatively large lithium abundance. We present the seismic analysis of HD 42618, and the modelling of the two solar analogues, HD 42618 and HD 43587 using the cestam stellar evolution code. Models were computed to reproduce the spectroscopic (effective temperature and metallicity) and seismic (mode frequency) data, and the luminosity of the stars, based on Gaia parallaxes. We infer very similar values of mass and radius for both stars compared with the literature, within the uncertainties, and we reproduce correctly the seismic constraints. The modelling shows that HD 42618 is slightly less massive and older than the Sun, and that HD 43587 is more massive and older than the Sun, in agreement with previous results. The use of chemical clocks improves the reliability of our age estimates. [ABSTRACT FROM AUTHOR]

Herbig Ae/Be (HAeBe) stars are the intermediate-mass analogues of low-mass T Tauri stars. Both groups may present signs of accretion, outflow, and IR excess related to the presence of circumstellar discs. Magnetospheric accretion models are generally used to describe accreting T Tauri stars, which are known to have magnetic fields strong enough to truncate their inner discs and form accretion funnels. Since few HAeBe stars have had magnetic fields detected, they may accrete through a different mechanism. Our goal is to analyse the morphology and variability of emission lines that are formed in the circumstellar environment of HAeBe stars and use them as tools to understand the physics of the accretion/ejection processes in these systems. We analyse high-resolution (R ∼ 47 000) UVES/ESO spectra of two HAeBe stars – HD 261941 (HAe) and V590 Mon (HBe) that are members of the young (∼3 Myr) NGC 2264 stellar cluster and present indications of sufficient circumstellar material for accretion and ejection processes to occur. We determine stellar parameters with synthetic spectra, and also analyse and classify circumstellar lines such as H α, H β, and He  i λ5875.7, according to their morphologies. We model the H α mean line profile, using a hybrid Magnetohydrodynamics (MHD) model that includes a stellar magnetosphere and a disc wind, and find signatures of magnetically driven outflow and accretion in HD 261941, while the H α line of V590Mon seems to originate predominantly in a disc wind. [ABSTRACT FROM AUTHOR]

The orbital motion of non-contact double-lined spectroscopic binaries (SB2s), with periods of a few tens of days to several years, holds unique, accurate information on individual stellar masses, which only long-term monitoring can unlock. The combination of radial velocity measurements from high-resolution spectrographs and astrometric measurements from highprecision interferometers allows the derivation of SB2 component masses down to the percent precision. Since 2010, we have observed a large sample of SB2s with the SOPHIE spectrograph at the Observatoire de Haute-Provence, aiming at the derivation of orbital elements with sufficient accuracy to obtain masses of components with relative errors as low as 1 per cent when the astrometric measurements of the Gaia satellite are taken into account. In this paper, we present the results from 6 yr of observations of 14 SB2 systems with periods ranging from 33 to 4185 days. Using the TODMOR algorithm, we computed radial velocities from the spectra and then derived the orbital elements of these binary systems. The minimum masses of the 28 stellar components are then obtained with an average sample accuracy of 1.0 ± 0.2 per cent. Combining the radial velocities with existing interferometric measurements, we derived the masses of the primary and secondary components of HIP 61100, HIP 95995 and HIP 101382 with relative errors for components (A,B) of, respectively, (2.0, 1.7) per cent, (3.7, 3.7) per cent and (0.2, 0.1) per cent. Using the CESAM2K stellar evolution code, we constrained the initial He abundance, age and metallicity for HIP 61100 and HIP 95995. [ABSTRACT FROM AUTHOR]

In anticipation of the Gaia astrometric mission, a large sample of spectroscopic binaries has been observed since 2010 with the Spectrographe pour l'Observation des PHénomènes des Intérieurs Stellaires et des Exoplanètes spectrograph at the Haute-Provence Observatory. Our aim is to derive the orbital elements of double-lined spectroscopic binaries (SB2s) with an accuracy sufficient to finally obtain the masses of the components with relative errors as small as 1 per cent when the astrometric measurements of Gaia are taken into account. In this paper, we present the results from five years of observations of 10 SB2 systems with periods ranging from 37 to 881 d. Using the todmor algorithm, we computed radial velocities from the spectra, and then derived the orbital elements of these binary systems. The minimum masses of the components are then obtained with an accuracy better than 1.2 per cent for the 10 binaries. Combining the radial velocities with existing interferometric measurements, we derived the masses of the primary and secondary components of HIP 87895 with an accuracy of 0.98 and 1.2 per cent, respectively. [ABSTRACT FROM AUTHOR]

In anticipation of the Gaia astrometric mission, a sample of spectroscopic binaries is being observed since 2010 with the Spectrograph pour l'Observation des PHénomènes des Intérieurs stellaires et des Exoplanètes (SOPHIE) spectrograph at the Haute-Provence Observatory. Our aim is to derive the orbital elements of double-lined spectroscopic binaries (SB2s) with an accuracy sufficient to finally obtain the masses of the components with relative errors as small as 1 per cent when combined with Gaia astrometric measurements. In order to validate the masses derived from Gaia, interferometric observations are obtained for three SB2s in our sample with F-K components: HIP 14157, HIP 20601 and HIP 117186. The masses of the six stellar components are derived. Due to its edge-on orientation, HIP 14157 is probably an eclipsing binary. We note that almost all the derived masses are a few per cent larger than the expectations from the standard spectral type-mass calibration and mass-luminosity relation. Our calculation also leads to accurate parallaxes for the three binaries, and the Hipparcos parallaxes are confirmed. [ABSTRACT FROM AUTHOR]

In anticipation of the Gaia astrometric mission, a large sample of spectroscopic binaries has been observed since 2010 with the Sophie spectrograph at the Haute–Provence Observatory. Our aim is to derive the orbital elements of double-lined spectroscopic binaries (SB2s) with an accuracy sufficient finally to obtain the masses of the components with relative errors as small as 1 per cent when the astrometric measurements of Gaia are taken into account. Simultaneously, the luminosities of the components in the Gaia photometric band G will also be obtained. Our observation program started with 200 SBs, including 152 systems that were only known as single-lined. Thanks to the high efficiency of the Sophie spectrograph, an additional component was found for 25 SBs. After rejection of five multiple systems, 20 new SB2s were retained, including eight binaries with an evolved primary, and their mass ratios were derived. Our final sample contains 68 SB2s, including two late-type giants and 10 other evolved stars. [ABSTRACT FROM AUTHOR]

Thanks to their past history on the main-sequence phase, supergiant massive stars develop a convective shell around the helium core. This intermediate convective zone (ICZ) plays an essential role in governing which g-modes are excited. Indeed, a strong radiative damping occurs in the high-density radiative core but the ICZ acts as a barrier preventing the propagation of some g-modes into the core. These g-modes can thus be excited in supergiant stars by the κ-mechanism in the superficial layers due to the opacity bump of iron, at . However, massive stars are submitted to various complex phenomena such as rotation, magnetic fields, semiconvection, mass loss, overshooting. Each of these phenomena exerts a significant effect on the evolution and some of them could prevent the onset of the convective zone. We develop a numerical method which allows us to select the reflected, thus the potentially excited, modes only. We study different cases in order to show that mass loss and overshooting, in a large enough amount, reduce the extent of the ICZ and are unfavourable to the excitation of g-modes. [ABSTRACT FROM AUTHOR]

A comparison between linear-stability analysis and observations of pulsation modes in five δ Scuti stars, belonging to the same cluster, is presented. The study is based on a work by Michel et al., in which such a comparison was performed for a representative set of model solutions obtained independently for each individual star considered. In this paper, we revisit that work by Michel et al. following, however, a new approach which consists of the search for a single, complete, and coherent solution for all the selected stars, in order to constrain and test the assumed physics describing these objects. To do so, refined descriptions for the effects of rotation on the determination of the global stellar parameters and on the adiabatic oscillation frequency computations are used. In addition, a crude attempt is made to study the role of rotation on the prediction of mode instabilities. The present results are found to be comparable with those reported by Michel et al. Within the temperature range , agreement between observations and model computations of unstable modes is restricted to values for the mixing-length parameter . This indicates that for these stars a smaller value for is required than that suggested from a calibrated solar model. We stress the point that the linear-stability analysis used in this work still assumes stellar models without rotation and that further developments are required for a proper description of the interaction between rotation and pulsation dynamics. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the influence of the level of feed intake and a 2-d feed restriction period on the postweaning adaptation of pancreatic exocrine secretions. At 33 d of age, 18 piglets fitted with 2 permanents catheters (for pancreatic juice collection and reintroduction) were weaned and allocated to 1 of the following 2 dietary treatments for 5 d: restricted feed allocation (restricted) or gradually increasing feed allocation (control). Pancreatic juice was collected daily during both basal and prandial periods. The basal period was defined as the period from 1400 to 1700 h (i.e., 5 to 8 h after the morning meal), whereas the prandial period was defined as the period from 30 mm before to 60 mm after the morning meal (given at 0900). Digestive enzyme activities and anti-bacterial activity were determined. Pancreatic protein secretion was 44% less (P < 0.05) in restricted piglets than in control piglets during the basal period. Trypsin secretion was affected by feed-restriction of piglets. The meal did not affect protein and trypsin secretions in restricted piglets, whereas at d 3 postweaning, protein and trypsin secretions and trypsin specific activity in control piglets were 9-, 105-, and 25-fold greater (P < 0.00 1) during the first 30 mm after the meal than before the meal. Lipase and amylase secretions were not affected by variations in feed intake. The secretion of antibacterial activity in restricted piglets was greater (P < 0.05) than that of control piglets only at d 5. The extended feed restriction period increased the basal secretion of antibacterial activity (P = 0.09) and postprandial secretion of amylase (P = 0.05). In conclusion, a low level of feed intake during the early postweaning period decreased pancreatic protein and trypsin secretions, whereas a 2-d feed restriction period enhanced secretions of amylase and antibacterial activity. In addition, our results indicate that during periods of dietary adaptation, such as at weaning, measurements of enzyme activities in the tissue do not accurately reflect the enzyme secretion. [ABSTRACT FROM AUTHOR]

Focuses on the methodological approach of measuring mammary blood flow. Techniques used in ruminants for direct measurement of mammary blood flow; Cause of the lack of information on direct measurement of mammary blood flow in lactating sows; Result of the implantation of the ultrasonic probe in the sows.

The objective of this study was to determine the influence of the level of feed intake and a 2-d feed restriction period on the postweaning adaptation of pancreatic exocrine secretions. At 33 d of age, 18 piglets fitted with 2 permanents catheters (for pancreatic juice collection and reintroduction) were weaned and allocated to 1 of the following 2 dietary treatments for 5 d: restricted feed allocation (restricted) or gradually increasing feed allocation (control). Pancreatic juice was collected daily during both basal and prandial periods. The basal period was defined as the period from 1400 to 1700 h (i.e., 5 to 8 h after the morning meal), whereas the prandial period was defined as the period from 30 mm before to 60 mm after the morning meal (given at 0900). Digestive enzyme activities and anti-bacterial activity were determined. Pancreatic protein secretion was 44% less (P < 0.05) in restricted piglets than in control piglets during the basal period. Trypsin secretion was affected by feed-restriction of piglets. The meal did not affect protein and trypsin secretions in restricted piglets, whereas at d 3 postweaning, protein and trypsin secretions and trypsin specific activity in control piglets were 9-, 105-, and 25-fold greater (P < 0.00 1) during the first 30 mm after the meal than before the meal. Lipase and amylase secretions were not affected by variations in feed intake. The secretion of antibacterial activity in restricted piglets was greater (P < 0.05) than that of control piglets only at d 5. The extended feed restriction period increased the basal secretion of antibacterial activity (P = 0.09) and postprandial secretion of amylase (P = 0.05). In conclusion, a low level of feed intake during the early postweaning period decreased pancreatic protein and trypsin secretions, whereas a 2-d feed restriction period enhanced secretions of amylase and antibacterial activity. In addition, our results indicate that during periods of dietary adaptation, such as at weaning, measurements of enzyme activities in the tissue do not accurately reflect the enzyme secretion. [ABSTRACT FROM AUTHOR]