The ASTRI Mini-Array is an International collaboration, led by the Italian National Institute for Astrophysics (INAF), that is constructing and operating an array of nine Imaging Atmospheric Cherenkov Telescopes to study gamma-ray sources at very high energy (TeV) and perform optical stellar intensity interferometry observations.
Angular resolutions below 100 microarcsec are achievable with stellar intensity interferometry (SII), using telescopes separated by hundreds to thousands of meters baselines. At this level of resolution it turns out to be possible to reveal details on the surface and of the environment surrounding bright stars on the sky. The ASTRI Mini-Array will provide a suitable infrastructure for performing these measurements thanks to the capabilities offered by its 9 telescopes, which provide 36 simultaneous baselines over distances between 100 m and 700 m.
After providing an overview of the scientific context and motivations for performing SII science with the ASTRI Mini-Array telescopes, we present the baseline design for the ASTRI Stellar Intensity Interferometry Instrument (SI3), a fast single photon counting instrument that will be mounted on the ASTRI telescopes and dedicated to performing SII observations of bright stars.

In occasione della Notte Europea dei Ricercatori 2022, l’INAF-Osservatorio Astrofisico di Catania ha organizzato varie attività per il pubblico che si svolgeranno tra il 28 e il 30 settembre.

In occasione della Notte Europea dei Ricercatori 2022, l’INAF-Osservatorio Astrofisico di Catania ha organizzato varie attività per il pubblico che si svolgeranno tra il 29 settembre e l’1 ottobre.

The Oppenheimer-Snyder-Datt model for homogeneous dust collapse describes how a black hole forms. Considering semi-classical corrections at large curvature obtained from general relativity coupled to non-linear electrodynamics may lead to the resolution of the central singularity and the formation of a regular black hole.

Il 25 ottobre sarà possibile assistere da Catania a un'eclissi parziale di Sole, con inizio alle ore 11:36, massimo di visibilità alle 12:31 e fine alle 13:27.

Being able to constrain the rotation profile, both radial and latitudinal, of main-sequence solar-type stars, from the surface to the core, is a fundamental problem if we want to improve our understanding of stellar evolution (especially in order to get better constraints on stellar ages) and of the interactions of stars with their environment. As of today, the core rotation profile of the Sun and other main-sequence solar-type stars remains a mystery.

The radial velocity (RV) technique is one of the most successful method for detecting exoplanets and it is based on measuring the Doppler reflex motion induced on a star by its orbiting planets. However, the stellar activity in the form of oscillations, granulations, spots or faculae also produces Doppler signals which may completely hide the Keplerian signal of an exoplanet.

A thorough characterisation of an exoplanetary system includes also studying the evolution of planetary atmospheres. To this end, we developed a custom Python tool that we have dubbed PASTA: Planetary Atmospheres and Stellar roTation rAtes. The tool runs within a Bayesian framework and it adopts a MCMC scheme to estimate the atmospheric content of exoplanets at the dispersal of the protoplanetary disk accounting for the present day system observables. As a positive by-product, the evolution of the stellar rotation period is reconstructed as well. In detail, our tool relies on planetary evolutionary models relating mass, radius and equilibrium temperature with the expected atmospheric mass fraction and mass loss rate, the latter derived from hydrodynamic simulations. The atmospheric mass loss rate is significantly influenced by the stellar activity level, which is estimated from the stellar rotation period via empirical relations. In particular, gyrochronology and theoretical stellar evolutionary tracks are essential to evaluate the high-energy emission over time. We have successfully applied this framework to a number of recently discovered planets, including various CHEOPS targets. The synergy between CHEOPS and radial velocity spectrographs have already allowed us to identify different systems amenable to PASTA’s analysis, so to constrain the planet formation and stellar evolution.