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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.

Pint of Science 2024: Dalla Polvere ai Buchi Neri

Joyce Irish pub Via Montesano 46, Catania, Italia

Tu potresti morire ma il deserto nasconderebbe il segreto della tua morte che rimarrebbe dopo di te per coprire la tua memoria con il vento… scrive John Fante in Ask the dust, Chiedi quindi alla polvere ma di una stella se vuoi sapere cosa ci attende se cadessimo in un Buco Nero, dove lo spazio diventa tempo e il tempo diventa spazio, dove forse si cela il passaggio verso un nuovo Universo gemello del nostro. Siete pronti a questo viaggio cosmico?

ESP2024 – PLATO PLANETARY SYSTEMS: Formation to Observed architectures

Department of Physics and Astronomy "Ettore Majorana" (DFA) of the Catania University Via Santa Sofia 64, Catania, Italia

PLATO is the 3rd mission of class M in the ESA Cosmic Vision program. Its main goal is detecting terrestrial planets in the habitable zone of solar type stars. With its huge FOV, most of the PLATO targets are bright stars that will be monitored with high cadence (25 s) for at least 2-3 years during the long duration observing program, while contemporary a number of very bright stars in the sample will be observed with 2.5 s cadence. The collected data, photometry from space and high resolution spectroscopy from the ground, will provide accurate planetary structures as well as architectures and evolutionary stage - via asteroseismic analysis - of a large number of planetary systems. PLATO is planned for a launch in Dec 2026.

Pint of Science 2024: La conquista dello spazio

Joyce Irish pub Via Montesano 46, Catania, Italia

Partendo dallo storico viaggio di Gagarin, si parlerà di come il genere umano ha conquistato lo spazio che ci circonda, delle prospettive future a breve e lungo termine e, per i pochi a quel punto ancora ragionevolmente sobri, delle ricadute sulla vita di tutti i giorni delle tecnologie spaziali.