Abstract: Aims. We analyse particle, radio, and X-ray observations during the first relativistic proton event of solar cycle 25 detected on Earth. The aim is to gain insight into the relationship between relativistic solar particles detected in space and the processes of acceleration and propagation in solar eruptive events.Methods. To this end, we used ground-based neutron monitor measurements of relativistic nucleons and space-borne measurements of electrons with similar speed to determine the arrival times of the first particles at 1 AU and to infer their solar release times. We compared the release times with the time histories of non-thermal electrons in the solar atmosphere and their escape to interplanetary space, as traced by radio spectra and X-ray light curves and images.Results. Non-thermal electrons in the corona are found to be accelerated in different regions. Some are confined in closed magnetic structures expanding during the course of the event. Three episodes of electron escape to the interplanetary space are revealed by groups of decametric-to-kilometric type III bursts. The first group appears on the low-frequency side of a type II burst produced by a coronal shock wave. The two latter groups are accompanied at higher frequencies by bursts with rapid drifts to both lower and higher frequencies (forward- or reverse-drifting bursts). They are produced by electron beams that propagate both sunward and anti-sunward. The first relativistic electrons and nucleons observed near Earth are released with the third group of type III bursts, more than ten minutes after the first signatures of non-thermal electrons and of the formation of the shock wave in the corona. Although the eruptive active region is near the central meridian, several tens of degrees east of the footpoint of the nominal Parker spiral to the Earth, the kilometric spectrum of the type III bursts and the in situ detection of Langmuir waves demonstrate a direct magnetic connection between the L1 Lagrange point and the field lines onto which the electron beams are released at the Sun.Conclusions. We interpret the forward- and reverse-drifting radio bursts as evidence of reconnection between the closed expanding magnetic structures of an erupting flux rope and ambient open magnetic field lines. We discuss the origin of relativistic particles near the Earth across two scenarios: (1) acceleration at the CME-driven shock as it intercepts interplanetary magnetic field lines rooted in the western solar hemisphere and (2) an alternative where the relativistic particles are initially confined in the erupting magnetic fields and get access to the open field lines to the Earth through these reconnection events.

Abstract: Many marine vertebrates traverse more than hundreds of kilometres of the ocean. To efficiently achieve such long-distance movements, the ability to maintain orientation in a three-dimensional space is essential; however, it remains unevaluated in most species. In this study, we examined the bearing distributions of penguins undertaking long-distance foraging trips and compared their bearing consistency between underwater and at the water surface, as well as between night and day, to quantify their orientation ability. The subject species, king penguins, Aptenodytes patagonicus, from Possession Island, Crozet archipelago (46°25′S, 51°45′E; January to March 2011), showed high bearing consistency both during dives and at the water surface whilst commuting towards/from their main foraging area, the Antarctic polar front. Their bearing consistency was particularly high during and after shallow dives, irrespective of the time of day. Meanwhile, their bearings tended to vary during and after deep dives, particularly in the middle of the trip, probably owing to underwater foraging movements. However, the overall directions of deep dives during the commuting phases were similar to those of shallow dives and post-dive periods at the water surface. These findings indicate that king penguins employ compass mechanism(s) that are equivalently reliable both underwater and at the water surface, at any time of the day. This orientation ability appears to enable them to achieve long-distance trips under strong temporal constraints. Further studies on the fine-scale bearing distributions of other diving vertebrates are needed to better understand movement strategies in marine environments.

Abstract: Cosupervision: Barbraud &Amp; le Bohec