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Space-Weathering on Primitive Asteroids

Sede A. Riccò Via Santa Sofia 78, Catania

Studying small bodies in our solar system is fundamental for understanding its youth and evolution. These small "primitive" bodies are "undifferentiated" (they did not undergo phase density separation, irreversibly altering their mineralogy). They have evolved little since their creation, spurring a composition relatively close to the primordial proto-planetary disk. However, other processes, such as thermal alteration, aqueous alteration, shocks, or space-weathering, can affect these bodies' surfaces.

The Gravitational-Wave breakthrough we can(‘t) wait for

Sede A. Riccò Via Santa Sofia 78, Catania

Less than a decade after the first historical Gravitational Wave (GW) detection GW150914, the field of GW astronomy has grown at a phenomenal pace, going from less than an event per month, to the currently observed rate of few events a week.
Despite the exceptional contributions the field has brought to fundamental physics, astronomy, cosmology, computational physics as well as the unavoidable collateral progress in fields related to the experimental development of GW detectors, the picture is anything but complete.
Amongst the missing pieces of the puzzle we find Continuous Gravitational Waves (CGWs).
In this seminar I am going to talk about CGWs, what are they and what astrophysical sources and mechanisms can produce them, with a particular focus on non-axisymmetric spinning Neutron Stars.
I will also briefly discuss the different search implementations, what is done, or can be done, to increase our chances to arrive to what is probably going to be the next breakthrough in GW Astronomy, the first CGW detection, including a discussion about prospects in view of future observation runs as well as GW detectors operational in the close future.

The contribution of laboratory experiments in the study of organic matter in Solar-system bodies

Sede A. Riccò Via Santa Sofia 78, Catania

Organic matter is revealed in a variety of extraterrestrial bodies, including comets, asteroids, satellites, and trans-Neptunian objects. On atmosphere-less surfaces, organics are detected in the visible and near-infrared thanks to observations performed with the instruments on-board space probes and telescopes. Further information on the properties of organics comes from the analysis of meteorites, interplanetary dust particles, and unique samples collected on comets and asteroids during dedicated space missions.
Understanding the properties of organic matter present in small bodies would allow us to shed light on processes that happened at the dawn of the Solar System, when these objects formed by the aggregation of the materials available in the protoplanetary disk. However, since their formation, atmosphere-less surfaces were continuously exposed to energetic photons, solar particles, and cosmic rays that cause the alteration of organics, hindering to draw firm conclusions on their pristine composition and origin.
With the aim to support the interpretation of recent remote sensing observations and the analysis of extraterrestrial samples, we performed laboratory experiments to study the spectral properties of organics revealed in Solar System bodies, to shed light on the alteration induced by energetic charged particles, and to suggest possible pathways for the organics’ formation thanks to processes that involved molecular precursors already available in the pre-solar cloud.

RU Lup: the accretion environment of a prototypical Classical T Tauri star

Sede A. Riccò Via Santa Sofia 78, Catania

While it is well established that Classical T Tauri stars accrete material from a circumstellar disk through magnetic fields, the physics regulating the processes in the inner (0.1 AU) disk is still not well understood. With its long observational history and its rich emission line spectrum, RU Lup is a prime example to study this environment.

RU Lup is a monitoring target within the ULLYSES survey for Classical T Tauri stars. Optical spectroscopic observations with CHIRON and ESPRESSO were obtained simultaneously with the two epochs of the ULLYSES monitoring program for RU Lup.

In this talk, I will discuss the main results obtained by analyzing this collection of data, supplemented by the two TESS observations and the archival AAVSO photometry of RU Lup.
Using the high resolution ESPRESSO spectra, we improved the measurements of the stellar parameters, especially the projected rotational velocity (vsini).
We determined the veiling fraction for the ESPRESSO spectra, showing that the veiling consists of two components: a continuum emission likely originating in the accretion shock and line emission that fills in the photospheric absorption lines.
We detected a periodic modulation in the narrow component (NC) of the He I 5876 line with a period that is compatible with the stellar rotation period, indicating the presence of a compact region on the stellar surface that we identified as the footprint of the accretion shock. Although the brightness of RU Lup changed drastically both on daily and yearly timescales, this region is overall stable over the 3 years covered by the observations.
An analysis of the high-cadence TESS light curves revealed quasi-periodic oscillations (QPO) on timescales shorter than the stellar rotation period. This suggests that the accretion disk in RU Lup extends inward of the corotation radius and the star accretes through a magnetic boundary layer (MBL). The rich metallic emission line spectrum of RU Lup might be characteristic of this accretion regime.

Meet “LE” Researchers – IX Giornata delle donne e delle ragazze nella scienza

Città della Scienza via Simeto 23, Catania, Italia

Domenica 11 Febbraio si celebra la IX Giornata internazionale delle donne e delle ragazze nella scienza.
Il Centro Siciliano di Fisica Nucleare e di Struttura della Materia in collaborazione con l'Università di Catania, l'INAF Osservatorio Astrofisico di Catania e l'INFN Sezione di Catania, organizzano l'evento 𝐌𝐞𝐞𝐭 "𝐋𝐄" 𝐑𝐞𝐬𝐞𝐚𝐫𝐜𝐡𝐞𝐫𝐬 per raccontare e soprattutto far vedere dal vivo cosa fanno le ricercatrici delle materie STEM a Catania.

Investigating the link between protoplanets, disk substructures and disk winds

Sede A. Riccò Via Santa Sofia 78, Catania

Protoplanetary disks are now routinely observed around young stars but the planets they produce remain elusive to detect. So far, we have only one confirmed direct detection of protoplanets in the disk of PDS 70, with some tentative results (e.g. AB Aur). Yet disk structures are found almost ubiquitously across the sample of resolved disks. We are investigating the potential relationship between inner disk winds and outflows (traced by optical emission lines, such as ), and the presence and type of disk substructures. We aim to determine whether or not the various substructures are the direct results of protoplanet formation.
I will present new results from recent and archival observations of PDS 70. In order to investigate such connections between winds, substructures and planets, we turn to the one system where we have certainly detected the planets. We have carefully applied established techniques to the high-resolution spectra to reveal previously unseen forbidden emission profiles. These results suggest a significant wind originating from the inner disk. We compare these results and measurements of the mass accretion rate and disk properties to those of other weakly accreting young stars and those with transition disks.
We are also carrying out this investigation for the PENELLOPE/ULLYSES sample of ~80 young stars. This complements existing surveys of such winds/outflows, whilst allowing for further exploration of the relation to disk substructures, towards a more complete statistical survey.

Osservazione della luna

Un incontro dedicato all’avvistamento, assistito con strumentazione astronomica, della Luna Nuova di Ramadan.

Unlocking Cosmic Origins: LiteBIRD’s quest for Inflationary GWs

Sede A. Riccò Via Santa Sofia 78, Catania

The LiteBIRD (Lite (Light) satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection) experiment is a space mission dedicated to studying the polarization of the Cosmic Microwave Background (CMB). Its primary objective is to detect the faint B-mode polarization patterns in the CMB, which are believed to be imprints of gravitational waves from the early universe, particularly from the period of cosmic inflation. LiteBIRD is equipped with a 30 arcmin beam width and an extraordinarily low polarization noise of 2.16μK-arcmin, making it uniquely capable of capturing large scale full-sky CMB polarization.
Our studies address two significant challenges in detecting Inflationary B-modes: foregrounds and the weak gravitational lensing of the CMB.
Foregrounds, varying with observation frequency, can be mitigated through multi-frequency sky observations. However, gravitational lensing of the CMB presents a different problem, as it is not frequency-dependent and causes E-mode polarization to convert to B-modes. This conversion masks the primordial B-modes we aim to detect. Our work concentrates on estimating the mass distribution from the CMB field to create a template of lensing B-modes. By removing this lensing-induced B-mode template from the observational data, we enhance the sensitivity towards detecting Inflationary gravitational waves.
This talk will explore the methodologies used in this study, the challenges encountered, and the potential impact on the detection of the Inflationary gravitational waves.

Archeology of interstellar archipelagos: Reconstructing the lifecycle of star-forming clouds

Sede A. Riccò Via Santa Sofia 78, Catania

Determining how star-forming molecular clouds (MCs) arise from and interact with the diffuse interstellar medium (ISM) is crucial for understanding the initial conditions of planet and star formation and the evolution of the Milky Way and other similar galaxies. I will present state-of-the-art observations of neutral atomic hydrogen (HI) and interstellar magnetic fields, which, combined with numerical simulations and novel statistical tools based on machine vision, reveal three crucial aspects of the MC lifecycle. First, the signature of magnetization in the structure of MCs in the solar neighborhood, within 500 parsecs from the Sun. Two, the imprint of supernova feedback in the HI structure across the Galactic plane. And finally, the coupling between atomic and molecular gas in and around MCs. I will discuss the consequences of these findings for our understanding of the Galactic ecosystem and the prospects for radio-interferometric and submillimeter polarization observations from the forthcoming facilities.

MSC in Physics: which curriculum? (2024 edition)

Sede A. Riccò Via Santa Sofia 78, Catania

In collaborazione con il Dipartimento di Fisica e Astronomia, giorno 23 aprile 2024, con inizio alle ore 15:00, presso l'Osservatorio Astrofisico di Catania, avrà luogo l'iniziativa "Which Curriculum", rivolta alle studentesse e agli studenti della laurea triennale in Fisica come orientamento nella scelta della specializzazione per il corso magistrale.
Durante il pomeriggio, i ragazzi potranno visitare i nostri laboratori e parlare con i nostri ricercatori per conoscere e approfondire le attività scientifiche, i progetti in corso e le prospettive future.
L'incontro è promosso dalla Commissione Qualità del DFA.