Inicio: 12:00h
Ponente: Josep Miquel Girart Medina (ICE-CSIC)
Lugar: Zoom: https://us02web.zoom.us/j/85044910172?pwd=bXRmeWx3cTdDSzkrMFFJUXI5eE9hQT09 Meeting ID: 850 4491 0172 Passcode: 996691

The study of the formation and evolution of disks around young stars has been boosted since the Atacama Large Millimeter/submillimeter Array (ALMA) has been opened for science observations. While it is widely accepted that planets are formed in protoplanetary disks, there is still much debate on when this process happens. In a few cases protoplanets have been directly imaged, but for the vast majority of systems, disk gaps and cavities – seen especially by ALMA in dust continuum observations – have been the strongest evidence of recent or on-going planet formation. Here I will present two very different cases of star and planet formation that are occurring in a small nascent open cluster around/within the nearby molecular Barnard 59 molecular dense core. Interestingly, these two cases have been serendipitous discoveries with ALMA in a project where we were aimed to study the role of magnetic fields in the formation and evolution of accretion disks around young stars. 

Inicio: 12:00h
Ponente: Stefano Ascenzi (ICE)
Lugar: Zoom https://us02web.zoom.us/j/85044910172?pwd=bXRmeWx3cTdDSzkrMFFJUXI5eE9hQT09 Meeting ID: 850 4491 0172 Passcode: 996691

The X-ray emission of γ-ray burst (GRBs) is often characterized by an initial steep decay followed by a nearly constant emission phase (so-called "plateau") which can extend up to thousands of seconds. While the steep decay is usually interpreted as the tail of the prompt γ-ray flash, the long-lasting plateau is commonly associated to the emission from the external shock sustained by energy injection from a long-lasting central engine. In this talk I will present the result of a recent study, which propose an alternative interpretation, ascribing both the steep decay and the plateau to high-latitude emission (HLE) from a "structured jet" whose energy and bulk Lorentz factor depend on the angular distance from the jet symmetry axis. I will also show that even when the GRB is observed off-axis this model predicts a bright X-ray transient, which can constitute an interesting target for follow-up observational campaigns of gravitational wave events.