Three short-period Jupiters from TESS: HIP 65Ab, TOI-157b, and TOI-169b

We report the confirmation and mass determination of three hot Jupiters discovered by the Transiting Exoplanet Survey Satellite (TESS) mission: HIP 65Ab (TOI-129, TIC-201248411) is an ultra-short-period Jupiter orbiting a bright (V = 11.1 mag) K4-dwarf every 0.98 days. It is a massive 3.213 ± 0.078 MJ planet in a grazing transit configuration with an impact parameter of b = 1.17-0.08+0.10. As a result the radius is poorly constrained, 2.03-0.49+0.61RJ. The planet's distance to its host star is less than twice the separation at which it would be destroyed by Roche lobe overflow. It is expected to spiral into HIP 65A on a timescale ranging from 80 Myr to a few gigayears, assuming a reduced tidal dissipation quality factor of Qs′ = 107 - 109. We performed a full phase-curve analysis of the TESS data and detected both illumination- and ellipsoidal variations as well as Doppler boosting. HIP 65A is part of a binary stellar system, with HIP 65B separated by 269 AU (3.95 arcsec on sky). TOI-157b (TIC 140691463) is a typical hot Jupiter with a mass of 1.18 ± 0.13 MJ and a radius of 1.29 ± 0.02 RJ. It has a period of 2.08 days, which corresponds to a separation of just 0.03 AU. This makes TOI-157 an interesting system, as the host star is an evolved G9 sub-giant star (V = 12.7). TOI-169b (TIC 183120439) is a bloated Jupiter orbiting a V = 12.4 G-type star. It has a mass of 0.79 ±0.06 MJ and a radius of 1.09-0.05+0.08RJ. Despite having the longest orbital period (P = 2.26 days) of the three planets, TOI-169b receives the most irradiation and is situated on the edge of the Neptune desert. All three host stars are metal rich with [Fe / H] ranging from 0.18 to0.24

Global and local climatic cycles recorded by vegetation in the Mediterranean region during the Early-Middle Pleistocene transition.

Présentation oraleEarth climate was affected by a relatively progressive cooling during the Pliocene and the Pleistocene. This cooling trend was constituted by successive climate cycles. Cycles of 41 kyr-long were recognized during the early Pleistocene and were forced by the obliquity orbital parameter. During the Middle Pleistocene, cycles of 100 kyr-long were forced by the eccentricity (precession modulator). The shift from the “41 kyr world” to the “100 kyr world” was a period of increased cooling called the Mid Pleistocene Transition (MPT: 1.200 to 0.500 Ma). The marine isotopic stages (MIS) characterized the increasing duration of climatic cycles associated with a reinforced precession influence during the MPT. However, the oxygen isotopic proxy shows weak precessional control in marine Pleistocene sediments. As the Mediterranean region is under the influence of both obliquity and precession and because the heat-transfer from low to high latitudes is almost entirely supported by atmospheric transport, vegetation from Mediterranean region is expected to record climatic conditions, which experienced this atmospheric transport. Pollen analysis has been performed on five sections: Site ODP 976 (Alborean Sea), Santa Lucia and Montalbano Jonico (South Italy), Tsampika (Rhodes, Greece) and Shamb (Armenia). These sections are placed along a 4,000 km long transect from the Western Mediterranean region to Little Caucasus. Calibrations of these marine and continental sections were provided by integration of results from magnetostratigraphic and radiochronological dates as well as foraminiferal and nannofossil biostratigraphic events. More than 100,000 pollen grains were counted and permitted the construction of pollen diagrams, which were correlated with foraminiferal oxygen isotopic measurements provided by the same samples or close sections. Palynology was used to reconstruct vegetation modifications, which show the same cyclic vegetation change pattern related to climatic cycles that occurred during the Early-Middle Pleistocene (1.400-0.700 Ma). “Long-term” vegetation successions were controlled by climatic cycles and related to climate response to obliquity forcing. A similar vegetation dynamics with shorter and longer-term durations were forced by climate responses to precession and its modulator (the eccentricity), respectively. As influences of both parameters were superimposed in the vegetation, before and during the Mid-Pleistocene Transition, the expected shift from obliquity to 100 ka long-cycles related to eccentricity is not observed

Early Pleistocene climate changes in the central Mediterranean region as inferred from integrated pollen and planktonic foraminiferal stable isotope analyses

International audienceVegetation inherited from a Pliocene subtropical climate evolved through obliquity oscillations and global cooling leading to modern conditions. An integrated, highly time-resolved record of pollen and stable isotopes (δ18O and δ13C of Globigerina bulloides) was obtained to understand vegetation responses to Early Pleistocene climate changes. Continental and marine responses are compared in the Central Mediterranean region with a particular consideration of environmental changes during anoxic events. Pollen data illustrate vegetation dynamics as follows: [1] development of mesothermic elements (warm and humid conditions); [2] expansion of mid- and high-altitude elements (cooler but still humid conditions); and [3] strengthening of steppe and herb elements (cooler and dry conditions). These successions correlate with precession. δ18O variations recorded by Globigerina bulloides define two cycles (MIS 43-40) related to obliquity. At northern low- to mid-latitudes, the pollen signal records temperature and wetness changes related to precession even during global climate changes induced by obliquity. This may result in unexpected increasing wetness during glacial periods, which has to be considered specific to the Central and Eastern Mediterranean region. Lastly, an analysis of anoxic events reveals that enhanced runoff is indicated by increasing frequency of the riparian trees Liquidambar and Zelkova

Carbonate sedimentation on the Amazon shelf: depositional evolution and new age constraints on the burial of a tropical carbonate platform

International audienceThe continental shelf offshore the present-day Amazon River is known to have hosted a mixed carbonate-siliciclastic platform from the Late Paleocene to the Late Miocene. However, character of this platform has not been properly described and the nature and timing of the cessation of carbonate sedimentation remains controversial. In the present work, we investigate the Neogene succession of the Offshore Amazon basin, based on the stratigraphic analysis of a grid of 2D/3D seismic reflection data, correlated to revised micropaleontological data from exploration wells. This allows us to propose a new model for the transition from carbonate platform to siliciclastic sedimentation, which is shown to have varied through time across three different sectors of the shelf. In the Central and SE shelves, carbonate gave way to terrigenous sedimentation at some point between 9.1-7.78 Ma (probably around 8 Ma), whereas on the NW shelf, carbonate production persisted until 4.0-3.7 Ma. Longer-lasting carbonate sedimentation in the latter area can be explained by a lesser influx of siliciclastic sediments, favored by the development of a ca.150-km wide embayment in the Central shelf that directed terrigenous sediments sourced from the paleo-Amazon River directly to the continental slope and deep ocean. Carbonate environments persisted across the NW shelf until 5.5 Ma, keeping up with base level oscillations by aggradation. From 5.5-3.7 Ma (Early Pliocene), increasing sediment supply from the paleo-Amazon river reached the NW shelf resulting in the progressive burial of inner-shelf carbonates beneath a prograding siliciclastic wedge up to 85 m thick. Around 3.7 Ma, the Central shelf embayment was completely infilled and lager volumes of sediments supplied by the paleo-Amazon river were transported to the NW shelf, which finally promoted the burial of carbonate-dominated environments everywhere on the basin. Thereafter, carbonate environments were restricted to reef-like features recognized on seismic data as bodies locally interbedded with muddy Plio-Quaternary succession, generally 1-3.5 km wide, but up to 55 km in extension near the present and previous paleoshelf breaks, attesting to reduced terrigenous influx to the outer shelf during interglacial marine transgressions. The end of the carbonate platform was favoured by a combination of sea-level lowering and increasing terrigenous sediment supply after ca. 8 Ma that is also linked to the rapid growth of the Amazon deep-sea fan.AcknowledgementsThe authors gratefully acknowledge financial support during the completion of this study by CAPES (Coordination for the Improvement of Higher Level Education-Brazil) and the European Union’s Horizon 2020 research and innovation programme (Marie Skłodowska-Curie grant). Our special thanks are also due to the Brazilian National Petroleum and Gas Agency (ANP), CGG, GAIA, FUGRO and the Brazilian Navy for supplying data and for permission to publish our results

Hydrogéomorphologie du site, paléoenvironnements et dynamique alluviale

In Landuré C., Arcelin P., Arnaud-Fassetta G. (Eds.) Le village de La Capelière en Camargue (Arles, Bouches-du-Rhône) du début du Ve s. av. n. è. à la période du Haut Moyen Âge - 201

Neogene evolution and demise of the Amapá carbonate platform, Amazon continental margin, Brazil

International audienceThe Amazon continental shelf hosted one of the world's largest mixed carbonate-siliciclastic platforms from the late Paleocene onwards - the Amapá carbonates. The platform architecture, however, remains poorly understood and causes and timing of the cessation of carbonate deposition are still controversial. Here we present a stratigraphic analysis of the Neogene succession of the Amapá carbonates, based on a grid of 2D/3D seismic data correlated to revised micropaleontological data from exploration wells. The results provide improved constraints on the age of the transition from predominantly carbonate to siliciclastic sedimentation, which is shown to have varied through time across three different sectors of the shelf (NW, Central and SE). Four Neogene evolutionary stages of carbonate deposition could be defined and dated with reference to the new age model: (1) between ca. 24 and 8 Ma a predominantly aggrading mixed carbonate-siliciclastic shelf prevailed across the entire region carbonate production gave way to siliciclastic sedimentation across the Central and SE shelves; (2) between 8 and 5.5 Ma carbonate production continued to dominate the NW shelf, as deposition was able to keep up with base level oscillations; (3) between 5.5 and 3.7 Ma (early Pliocene), sediment supply from the paleo-Amazon River promoted the progressive burial of carbonates on the inner NW shelf, while carbonates production continued on the outer shelf (until 3.7 Ma). Longer-lasting carbonate sedimentation on the NW shelf can be explained by a lesser influx of siliciclastic sediments due to the paleo-geography of the Central shelf, characterized by a 150-km-wide embayment, which directed most terrigenous sediments sourced from the paleo-Amazon River to the continental slope and deep ocean; (4) from 3.7 Ma onwards, when the Central shelf embayment became completely filled, continuous sediment supply to the NW shelf resulted in the final transition from carbonate to siliciclastic-dominated environments on the entire Offshore Amazon Basin