The status and science of the Proba-3 mission

Dr. Stanislav Gunar
Astronomical Institute of the Czech Academy of Sciences

The giant distributed coronagraph ASPIICS onboard the formation-flying mission PROBA-3 of ESA investigates the hitherto practically unexplored inner depths of the solar corona. This region lies above the reach of disk imagers such as SDO/AIA and below the inner limit of other space coronagraphs. Although difficult to observe, the inner corona is a place of great interest. This is where the fast solar wind gets accelerated to supersonic velocities and where CMEs also reach their maximum accelerations. It is also the place where the transition between the regions of the closed and open magnetic field often happens and the slow solar wind originates.

We will present the current status and the most recent scientific results obtained by the Proba-3 mission. We will also look at the unique concept of the formation-flying technology that is the focus of the PROBA-3 mission and the workings of ASPIICS, and discuss which scientific fields are benefiting from its capabilities. For example, thanks to its field of view reaching from 1.098 to 3 Rsun, good spatial resolution and minimized straylight, ASPIICS is able to follow the connectivity of magnetic structures in the corona down to the solar surface. When coupled with regular long duration (up to 6 hours) observations, it allows us to compare and validate the MHD models of the large-scale coronal magnetic field configuration and its evolution. The inner field-of-view limit reaching very close to the solar surface also enables us to study the onset and early evolution of CMEs or to follow erupting prominences beyond the reaches of the disk imagers.

Conference Room A (1257) (2nd floor/ New Building A),　Via Zoom

Emerging boundaries in the planet formation process

Dr. Erik Petigura
University of California, Los Angeles

The eight planets in the solar system fall neatly into three main categories: rocky terrestrials, hydrogen-dominated Jovians, and ice giants. These planet classes reflect different formation environments, processes, and timescales. Extrasolar planets, in contrast, span a continuum of sizes, masses, and orbit. They demand a richer taxonomy. Recently, large, multivariate studies of transiting exoplanets have revealed new dividing lines in the planet formation process. Transitions in the occurrence, eccentricity, and host star metallicity distributions have shown that close-in planets larger than Neptune form according to very different pathways compared to their smaller counterparts. At the same time, new synergies involving RVs, direct imaging, and astrometry are beginning to illuminate the boundaries between the most massive planets (formed by core accretion) and the least massive brown dwarfs (formed by direct collapse). Surprisingly, this empirical boundary occurs well below the deuterium burning limit. Studies like this offer a preview of the types of insights we can look forward to with the upcoming release of Gaia DR4 in December of this year, which will dramatically expand our census of giant planets and brown dwarfs.

Conference Hall (2nd floor/ Research and Administration Building A),　Via Zoom

The centre of the Milky Way

Dr. Mattia Sormani
University of Insubria (Como, Italy)

I will give an introduction to the structure and dynamics of the central 3 kpc of the Milky Way. The Galactic bar efficiently drives gas from the Galactic disc towards the centre at a rate of ~0.8 Msun/yr, creating a ring-like accumulation of molecular gas at a radius of R=120pc known as the Central Molecular Zone (CMZ). The CMZ is the Milky Way analogue of the star-forming nuclear rings commonly observed at the centre of external barred galaxies, and its formation is governed by a dynamical process similar to that responsible for creating gaps in Saturn's rings. Once in the CMZ ring, approximately 10% of the gas is converted into stars by intense star formation activity. Over Gyr timescales, this activity builds up a flattened stellar system known as the nuclear stellar disc (NSD), which currently has a mass of 10^9 Msun and dominates the gravitational potential of the Milky Way at 30pc<R<300pc. Most of the remaining gas is ejected perpendicularly to the plane by a Galactic outflow powered either by stellar feedback and/or AGN activity. A small fraction continues moving radially inwards, feeding the circum-nuclear disc (CND) at radii of few pc and contributing to the in-situ growth of the nuclear star cluster (NSC). Only a tiny fraction eventually enters the sphere of influence of the central black hole SgrA* at R<1pc.

Conference Hall (2nd floor/ Research and Administration Building A),　Via Zoom