Calendar

First applications of the Sun-as-an-Xray-star method have used a grid of synthetic “stellar-like” X-ray spectra based on emission measures for different types of solar coronal structures like background corona, active regions, cores of active regions and flares. The target star’s coronal filling factor with these regions was then found by finding the grid-point closest to the observed X-ray spectrum of the star (e.g., Coffaro+2020). We have now further developed this method into spectral models using XSPEC that correspond to the different solar magnetic structures (background corona, active regions, cores of active regions and flares). Using these models, the hypothetical filling factors of these regions can be recovered.

For the first time, we apply the Sun-as-an-Xray-star method to a star which significantly differs from our Sun, AD Leo, in order to investigate how far the postulated solar-stellar analogy can be stretched. The early-M dwarf AD Leo is the ideal benchmark for stellar activity in the low-mass regime and its influence on planet atmospheres due to its proximity (5 pc) and high activity level, allowing for high-signal X-ray observations. In this project, we aim to reconstruct an X-ray corona of AD Leo, assuming it is covered by solar magnetic structures. We apply the XSPEC implementation of the Sun-as-an-Xray-star method to AD Leo spectra from eROSITA and XMM-Newton, and investigate the results of its application.

Titolo: “Da Piazzi in poi: oltre duecento anni di attività dell’Osservatorio Astronomico di Palermo”

Abstract: Saranno esaminati i principali contributi scientifici dati dall’Osservatorio di Palermo allo sviluppo dell’astronomia nel corso della sua pluricentenaria attività scientifica, soffermandosi sui periodi più significativi e sui fattori che hanno determinato gli importanti risultati scientifici ottenuti, dalla fine del Settecento agli ultimi decenni del secolo scorso, dagli astronomi in forze all’Osservatorio.

Titolo: Bright late-type stars in the thin Disk of the Milky Way

Abstract: Red supergiants (RSGs) and asymptotic giant branch (AGB) stars are the
brightest sources at infrared wavelengths, detectable at a distance
of a few  megaparsecs —- even in heavily obscured galactic centers.
Through winds and mass loss, they enrich and sculpt the interstellar
medium.
Despite similar spectral energy distributions and apparent magnitudes,
RSGs and AGBs trace distinct spatial structures of a galaxy.
AGBs trace well the gravitational potential, including the central bar,
and span ages from 50 Myr to a Hubble time. RSGs, aged 4.5–40 Myr, decorate
the spiral arms, the central molecular disk, and the bar’s endpoints.
The Milky Way offers the nearest laboratory for resolved stellar
populations
in a barred galaxy, however, dust obscuration and distance uncertainties
hinder
clean separation of RSGs and AGBs -— a critical step for mapping Disk
structure
and star-formation history.
Over the past several years, I have developed methods to estimate
extinction
by partitioning interstellar and circumstellar components, to obtain better
luminosity and to distinguish RSGs from AGBs. I will highlight key
challenges
and solutions, including extinction-free colors as interstellar
extinction proxies,
GLIMPSE color–color diagrams, and Gaia–2MASS criteria.
Finally, I will present a new Gaia catalog of ~700 bona fide optical RSGs,
detailing its construction, temperature, and luminosity characterization.