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International audience ; The weekly abundances of the sexual phase (aggregate zooid) of 2 salp populations (tunicates Thalia democratica and Salpa fusiformis) were determined from 1967 to 1990 at a fixed station in the coastal waters of the Western Mediterranean, using a discrete scale of abundance. For both species, the abundance time series shows the occasional development of blooms of aggregate zooids. Several hydrological and meteorological variables were recorded concomitantly, and their influence on the occurrence of blooms was evaluated using a Markov regression model for ordinal time series. Abundance at Week t was found to depend on the size of the population for the 2 previous weeks and on environmental variables. The influence of hydrological variables, air temperature and irradiance corresponds to the relationship between seasonal stratification of the water column and occurrence of blooms: the stronger the stratification, the lower the probability of observing high densities of salps. Wind stress was also found to exert a significant influence, with gusts of wind facilitating the development of blooms through the renewal of the pelagic production. The influence of easterly winds, which involves a process of surface waters accumulating near the coast, is limited to T. democratica. Conversely, the influence of westerly winds, which leads to local upwelling, is limited to S. fusiformis. These results are consistent with known differences in the spatial distribution of T. democratica and S. fusiformis with respect to both distance to the coast and depth.

International audience ; The weekly abundances of the sexual phase (aggregate zooid) of 2 salp populations (tunicates Thalia democratica and Salpa fusiformis) were determined from 1967 to 1990 at a fixed station in the coastal waters of the Western Mediterranean, using a discrete scale of abundance. For both species, the abundance time series shows the occasional development of blooms of aggregate zooids. Several hydrological and meteorological variables were recorded concomitantly, and their influence on the occurrence of blooms was evaluated using a Markov regression model for ordinal time series. Abundance at Week t was found to depend on the size of the population for the 2 previous weeks and on environmental variables. The influence of hydrological variables, air temperature and irradiance corresponds to the relationship between seasonal stratification of the water column and occurrence of blooms: the stronger the stratification, the lower the probability of observing high densities of salps. Wind stress was also found to exert a significant influence, with gusts of wind facilitating the development of blooms through the renewal of the pelagic production. The influence of easterly winds, which involves a process of surface waters accumulating near the coast, is limited to T. democratica. Conversely, the influence of westerly winds, which leads to local upwelling, is limited to S. fusiformis. These results are consistent with known differences in the spatial distribution of T. democratica and S. fusiformis with respect to both distance to the coast and depth.

Context. Shadows in scattered light images of protoplanetary disks are a common feature and support the presence of warps or misalignments between disk regions. These warps are possibly caused by an inclined (sub-)stellar companion embedded in the disk. Aims. We aim to study the morphology of the protoplanetary disk around the Herbig Ae star HD 139614 based on the first scattered light observations of this disk, which we model with the radiative transfer code MCMax3D. Methods. We obtained J- and H-band observations that show strong azimuthal asymmetries in polarized scattered light with VLT/SPHERE. In the outer disk, beyond similar to 30 au, a broad shadow spans a range of similar to 240 deg in position angle, in the east. A bright ring at similar to 16 au also shows an azimuthally asymmetric brightness, with the faintest side roughly coincidental with the brightest region of the outer disk. Additionally, two arcs are detected at similar to 34 and similar to 50 au. We created a simple four-zone approximation to a warped disk model of HD 139614 in order to qualitatively reproduce these features. The location and misalignment of the disk components were constrained from the shape and location of the shadows they cast. Results. We find that the shadow on the outer disk covers a range of position angles too wide to be explained by a single inner misaligned component. Our model requires a minimum of two separate misaligned zones - or a continuously warped region - to cast this broad shadow on the outer disk. A small misalignment of similar to 4 degrees between adjacent components can reproduce most of the observed shadow features. Conclusions. Multiple misaligned disk zones, potentially mimicking a warp, can explain the observed broad shadows in the HD 139614 disk. A planetary mass companion in the disk, located on an inclined orbit, could be responsible for such a feature and for the dust-depleted gap responsible for a dip in the SED. ; SO Centre National de la Recherche Scientifique (CNRS) MPIA (Germany) Istituto Nazionale Astrofisica (INAF) FINES (Switzerland) NOVA (The Netherlands) European Union (EU) RII3Ct2004-001566 European Union (EU) 226604 312430 Netherlands Organisation for Scientific Research (NWO) TOP-1 grant as part of the research program "Herbig Ae/Be stars, Rosetta stones for understanding the formation of planetary systems" 614.001.552 French National Research Agency (ANR) ANR16-CE31-0013 CONICYT + PAI/Convocatoria nacional subvencion a la instalacion en la academia, convocatoria 2017 + Folio PAI77170087

Context. We initiated a deep-imaging survey of Scorpius-Centaurus A-F stars in 2015. These stars are predicted to host warm inner and cold outer belts of debris reminiscent of the architecture of emblematic systems such as HR 8799. Aims. We present resolved images of a ring of debris around the F5-type star HD 141011 that was observed as part of our survey. We aim to set constraints on the properties of the disk, compare them to those of other resolved debris disks in Sco-Cen, and detect companions. Methods. We obtained high-contrast coronagraphic observations of HD 141011 in 2015, 2016, and 2019 with VLT/SPHERE. We removed the stellar halo using angular differential imaging. We searched for scattered light emission from a disk in the residuals and applied a forward-modeling approach to retrieve its morphological and photometric properties. We combined our radial velocity and imaging data to derive detection probabilities for companions co-planar with the disk orientation. Results. We resolve a narrow ring of debris that extends up to ∼1.100 (∼141 au) from the star in the IRDIS and IFS data obtained in 2016 and 2019. The disk is not detected in the 2015 data which are of poorer quality. The disks is best reproduced by models of a noneccentric ring centered on the star with an inclination of 69.1 ± 0.9 ◦ , a position angle of −24.6 ± 1.7 ◦ , and a semimajor axis of 127.5 ± 3.8 au. The combination of radial velocity and imaging data excludes brown-dwarf (M > 13.6 MJup) companions coplanar with the disk from 0.1 to 0.9 au and from 20 au up to 500 au (90% probability). Conclusions. HD 141011 adds to the growing list of debris disks that are resolved in Sco-Cen. It is one of the faintest disks that are resolved from the ground and has a radial extent and fractional width (∼12.5%) reminiscent of Fomalhaut. Its moderate inclination and large semimajor axis make it a good target for the James Webb Space Telescope and should allow a deeper search for putative companions shaping the dust distribution. ; French National Research Agency (ANR) ANR-14-CE33-0018 ANR-20-CE31-0012 France from the CNRS-D2P PICS grant France from the Programmes Nationaux de Planetologie et de Physique Stellaire (PNP) France from the Programmes Nationaux de Planetologie et de Physique Stellaire (PNPS) European Research Council (ERC) 885 593 Istituto Nazionale Astrofisica (INAF) Agenzia Spaziale Italiana (ASI) 2018-16-HH.0 PRIN-INAF 2019 "Planetary systems at young ages (PLATEA)" Australian Research Council FT170100040 DP180104235 ANID, -Millennium Science Initiative Program NCN19_171 Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 1180395 French National Research Agency (ANR) ANR10 LABX56 Spanish Government AyA2017-84089 European Commission 776403 Universidad de Valparaiso ; Versión publicada - versión final del editor

The study of hot corinos in solar-like protostars has been so far mostly limited to the Class 0 phase, hampering our understanding of their origin and evolution. In addition, recent evidence suggests that planet formation starts already during Class I phase, which therefore represents a crucial step in the future planetary system chemical composition. Hence, the study of hot corinos in Class I protostars has become of paramount importance. Here, we report the discovery of a hot corino towards the prototypical Class I protostar L1551 IRS5, obtained within the ALMA (Atacama Large Millimeter/submillimeter Array) Large Program FAUST (Fifty AU STudy of the chemistry in the disc/envelope system of solar-like protostars).We detected several lines from methanol and its isotopologues (13CH3OH and CH2DOH), methyl formate, and ethanol. Lines are bright towards the north component of the IRS5 binary system, and a possible second hot corino may be associated with the south component. The methanol lines' non-LTE analysis constrains the gas temperature (100 K), density (1.5 × 108 cm3), and emitting size (10 au in radius). All CH3OH and 13CH3OH lines are optically thick, preventing a reliable measure of the deuteration. The methyl formate and ethanol relative abundances are compatible with those measured in Class 0 hot corinos. Thus, based on this work, little chemical evolution from Class 0 to I hot corinos occurs. ; With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)