Calendar

Speaker: Elisa Guerriero (UNIPA)

Titolo: Development polishing process for bare aluminum mirrors to ARIEL space mission

Abstract: ARIEL is the 4th medium-class mission of ESA’s Cosmic Vision Programme to see and to study the exoplanets’ atmospheres in VIS/IR. The technical innovation of the project is the use of bare aluminum for the mirrors. This material is light, cheap, and available in large quantities, but difficult to polish because it is not very dense. In this seminar, I will talk about my work at Media Lario S.r.l. for the development of the aluminum polishing process, the critical issues and the results obtained.

Speaker: Darius Modirrousta Galian (UNIPA)

Titolo: Exploring Super-Earth Surfaces: Albedo of Near-Airless Magma Ocean Planets and Topography

Abstract:

Speaker: Salvatore Sciortino (INAF)

Titolo: A prototype Palermo- Wavelet Detection Code for the
ATHENA WFI: investigating the effect on detection of telescope (or lack of) baffle
and other new challenges posed by very deep exposures of a large area telescope

Abstract:

I will discuss the motivations for and the initial results of a prototype
version of the so-called Pwedetect code for the Athena WFI.  I will discuss the
use of this prototype for assessing the effect of stray-light in the detection
of weak sources with Athena and results from an on-going extensive set of
simulations that have already pinpoint some of the new challenges that the WFI
poses with respect to the past and current generation of X-ray imaging detectors.

Titolo:

Dalla Società degli Spettroscopisti Italiani alla Società Astronomica Italiana: storia della SAIt

Abstract:

Cent’anni fa, nel 1920, nel corso di una riunione tenutasi all’Accademia dei Lincei, nasceva la Società Astronomica Italiana, come risultato della trasformazione della Società degli Spettroscopisti Italiani. In questo talk saranno ripercorsi i passaggi salienti che hanno portato alla nascita della SAIt, con un breve excursus sui suoi primi cinquant’anni di vita.

ID Google Meet: >>> https://meet.google.com/sxz-cctp-tsc <<<

Speaker: Giada Genua

Titolo: Tutela, conservazione e restauro dei beni librari del fondo Piazzi, presso la Specola Universitaria di Palermo: primi risultati di un progetto di ricerca

Abstract:

Nel seminario verranno presentati i primi risultati del lavoro di conservazione e restauro attualmente in corso sui libri del fondo Piazzi, cioè la collezione libraria di proprietà del fondatore dell’Osservatorio Astronomico, lasciati in eredità all’istituto alla sua morte; la collezione costituisce dunque il nucleo originario della biblioteca dell’Osservatorio.
Verranno descritte le altre attività di ricerca svolte in parallelo: lo sviluppo di un database relazionale dettagliato sui libri del Fondo, utile per la condivisione e l’implementazione di futuri studi sull’argomento e lo studio sulle carte decorate presenti sulle legature di molti dei libri della collezione. Si discuteranno inoltre le tracce presenti in biblioteca delle interessanti relazioni di Piazzi con la Stamperia Reale, un’altra istituzione creata sul finire del ‘700 come parte del rinnovamento culturale e scientifico di Palermo.
Questa attività fa parte di un più ampio progetto mirato allo studio della fondazione e delle prime fasi di vita dell’Osservatorio Astronomico.

>>> ID Google meet: meet.google.com/sxz-cctp-tsc  <<<

Speaker: Emanuele Greco (UNIPA)

Titolo: Unveiling pure-metal ejecta X-ray emission in supernova remnants through their radiative recombination

Abstract:

Spectral analysis of X-ray emission from ejecta in supernova remnants (SNRs) is hampered by the low spectral resolution of CCD detectors, which typically creates a degeneracy between the best-fit values of chemical abundances and the plasma emission measure. The combined contribution of shocked ambient medium and ejecta to the emerging X-ray emission further complicates the determination of the ejecta mass and chemical composition. This degeneracy leads to big uncertainties in mass estimates and can introduce a bias in the comparison between the ejecta chemical composition derived from the observations and the yields predicted by explosive nucleosynthesis models. We explore the capabilities of present and future spectral instruments with the aim of identifying a spectral feature which may allow us to discriminate between metal-rich and pure-metal plasmas in X-ray spectra of SNRs. We studied the behaviour of the most common X-ray emission processes of an optically thin plasma in the high-abundance regime. We investigated spectral features of bremsstrahlung, radiative recombination continua (RRC) and line emission, by exploring a wide range of chemical abundances, plasma temperatures and ionization parameters. We then synthesized X-ray spectra from a state-of-the-art 3D hydrodynamic (HD) simulation of Cas A, by using the response matrix from the Chandra ACIS-S CCD detector and that of the XRISM/Resolve X-ray calorimeter spectrometer. We found that a bright RRC shows up when the plasma is made of pure-metal ejecta, and a high spectral resolution is needed to actually identify this ejecta signature. We tested and verified the applicability of our novel diagnostic tool and we propose a promising target for the future detection of such spectral feature: the southeastern Fe-rich clump of Cas A. We found that, while there is no way to unambiguously reveal pure-metal ejecta emission with CCD detectors, X-ray calorimeters will be able to pinpoint the presence of pure-metal RRC and to recover correctly absolute mass and the chemical composition of the ejecta, opening a new window on the link progenitor-supernova-remnant.

indirizzo Google Meet: meet.google.com/mbi-zdmh-vbp

Speaker: Scott Wolk (CfA)

Titolo: SEEJ: SmallSat Exosphere Explorer of hot Jupiters

Abstract:

The first detected exoplanets found were “hot Jupiters”; these are large Jupiter-like planets in close orbits with their host star. The stars in these so-called “hot Jupiter systems” can have significant X-ray emission and the X-ray flux likely changes the evolution of the overall star-planetary system in at least two ways: (1) the intense high energy flux alters the structure of the upper atmosphere of the planet – in some cases leading to significant mass loss; (2) the angular momentum and magnetic field of the planet induces even more activity on the star, enhancing its X-rays, which are then subsequently absorbed by the planet. If the alignment of the systems is appropriate, the planet will transit the host star. The resulting drop in flux from the star allows us to measure the distribution of the low-density planetary atmosphere. We describe a science mission concept for a SmallSat Exosphere Explorer of hot Jupiters (SEEJ; pronounced “siege”). SEEJ will monitor the X-ray emission of nearby X-ray bright stars with transiting hot Jupiters in order to measure the lowest density portion of exoplanet atmospheres and the coronae of the exoplanet hosts. SEEJ will use revolutionary Miniature X-ray Optics (MiXO) and CMOS X-ray detectors to obtain sufficient collecting area and high sensitivity in a low mass, small volume and low-cost package. SEEJ will observe scores of transits occurring on select systems to make detailed measurements of the transit depth and shape which can be compared to out-of-transit behavior of the target system. The depth and duration of the flux change will allow us to characterize the exospheres of multiple hot Jupiters in a single year. In addition, the long baselines (covering multiple stellar rotation periods) from the transit data will allow us to characterize the temperature, flux and flare rates of the exoplanet hosts at an unprecedented level. This, in turn, will provide valuable constraints for models of atmospheric loss. In this contribution we outline the science of SEEJ and focus on the enabling technologies Miniature X-ray Optics and CMOS X-ray detectors.

indirizzo Google Meet: meet.google.com/mbi-zdmh-vbp

Speaker: Raffaele D’Abrusco (CfA)

Titolo: The motif of globular clusters in and around elliptical galaxies

Abstract:

Our understanding of how galaxies evolve and interact with their environment depends critically on our ability to determine how they assembled. The abundance of observational probes of galactic assembly in the local Universe
contrasts with the scarcity of observationally viable approaches at larger distances and in more diverse environments.
In this talk, I will discuss the discovery of complex, extended two-dimensional structures in the spatial distribution of globular clusters (GCs) systems around massive early type galaxies (ETG) in the Virgo and Fornax clusters. A simple
prescription can be used to infer the properties of their progenitors and reconstruct the assembly history of their host, within the limitations imposed by the current availability of data. By expanding the investigation of the 2D spatial
distribution of GCs to the intra-cluster GC population in a massive cluster of galaxies, the growth of each host can be connected to the more general evolution of its environment and characterized as a function of the global properties
of the different GCs components. With simulations becoming capable of following the birth and evolution of GCs under several formation scenarios for the host galaxy, I will make the case that this method can extend significantly
our current capabilities to interpret physically the assembly of galaxies in observational regimes difficult to explore otherwise.