OA@INAF - Istituto Nazionale di Astrofisica
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A far-ultraviolet–driven photoevaporation flow observed in a protoplanetary disk
Full text linkMost low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modeling their kinematics and excitation allowed us to constrain the physical conditions within the gas. We quantified the mass-loss rate induced by the FUV irradiation and found that it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk...
Light-curve Structure and Hα Line Formation in the Tidal Disruption Event AT 2019azh
Full text linkAT 2019azh is a H+He tidal disruption event (TDE) with one of the most extensive ultraviolet and optical data sets available to date. We present our photometric and spectroscopic observations of this event starting several weeks before and out to approximately 2 yr after the g-band's peak brightness and combine them with public photometric data. This extensive data set robustly reveals a change in the light-curve slope and a possible bump in the rising light curve of a TDE for the first time, which may indicate more than one dominant emission mechanism contributing to the pre-peak light curve. Indeed, we find that the MOSFiT-derived parameters of AT 2019azh, which assume reprocessed accretion as the sole source of emission, are not entirely self-consistent. We further confirm the relation seen in previous TDEs whereby the redder emission peaks later than the bluer emission. The post-peak bolometric light curve of AT 2019azh is better described by an exponential decline than by the canonical t ‑5/3 (and in fact any) power-law decline. We find a possible mid-infrared excess around the peak optical luminosity, but cannot determine its origin. In addition, we provide the earliest measurements of the Hα emission-line evolution and find no significant time delay between the peak of the V-band light curve and that of the Hα luminosity. These results can be used to constrain future models of TDE line formation and emission mechanisms in general. More pre-peak 1–2 days cadence observations of TDEs are required to determine whether the characteristics observed here are common among TDEs. More importantly, detailed emission models are needed to fully exploit such observations for understanding the emission physics of TDEs
Finite Element Analysis of SRT's L-P band receiver support
Full text linkAs well as scientific research is continuously evolving, the Sardinia Radio Telescope also follows the trend of technological progress. New receivers will be installed on the facility in order to offer a wide-range and always state-of-the-art service. This report proposes a structural strength analysis of a frame which supports one of the Sardinia Radio Telescope’s receivers, the L-P band receiver, performed by the Finite Element Method. The obtained results have made possible to evaluate the use of the same frame design for other receivers. In addition, an alternative solution has been investigated to assess any room for improvement for the current support
Advanced gas-microphysics
Full text linkThis chapter contains the description of a miscellanea of microphysical processes incorporated in most numerical codes for studying the thermal and dynamical properties of the interstellar medium. They include the expressions of the ambipolar, Hall, and Ohm resistivities of a weakly ionized gas; the formulae to compute the internal energy and adiabatic index of a hydrogen-helium mixture; the relations between forward and backward cross-sections and rate coefficients according to the principle of detailed balance. The goal of this chapter is to provide a collection of ready-to-use formulae for numerical evaluation
Thermodynamics of the atomic and molecular gas
Full text linkEach phase of the ISM has a temperature that results from a balance of heating and cooling. These processes differ from place to place in the Galaxy and vary with time. Under particular conditions, the resulting thermal equilibrium can be unstable and promote the separation of coexisting thermodynamic phases in pressure equilibrium with each other. Determining the temperature is a big challenge for numerical modeling as many different microphysical processes have to be considered and, usually, simplifying assumptions have to be made. This chapter discusses the most important known heating and cooling processes for various physical conditions (i.e., from the diffuse ISM to planet-forming disks). We provide the necessary equations and references to the required data but also discuss simplified methods and their assumptions for each process. We conclude with a brief description of how to solve the heating/cooling balance considering different levels of complexity
La valutazione delle attività di Public Engagement: primi risultati ottenuti nei casi studio di Pint of Science, Notte Europea dei ricercatori e Non solo stelle cadenti
Full text linkSi propongono i primi risultati relativi a tre casi studio di valutazione d’impatto per attività di public engagement svolte nell’ambito di particolari eventi a coinvolgimento INAF diventati appuntamenti fissi annuali e in particolare il Festival Pint of Science (edizioni 2022 e 2023), la manifestazione Notte Europea dei Ricercatori (edizioni 2022 e 2023), e l’evento Non solo stelle cadenti organizzato presso l’Osservatorio Astronomico di Monte Zugna della Fondazione Musei Civici di Rovereto (TN) nel 2023. Per tali eventi è stata progettata e quindi implementata una valutazione che ha dovuto necessariamente essere pianificata a seconda del contesto, delle attività previste e della tipologia di evento, al fine di ottenere una serie di dati utili a valutare il raggiungimento degli obiettivi e quindi l’impatto di tali attività migliorando l’esperienza per i partecipanti. Si forniscono i dati raccolti e i primi risultati ottenuti utilizzati per la pianificazione delle successive edizioni delle manifestazioni
EduINAF: la valutazione degli insegnanti 2022/2023
Full text linkNell’anno 2022/2023, per conoscere l’opinione della classe docente sulle offerte EduINAF, si è deciso di realizzare un questionario di valutazione da proporre annualmente agli insegananti che leggono e utilizzano EduINAF, partecipando alle varie iniziative. In questo Report vengono riportati e analizzati i dati raccolti nel primo anno di questo monitoraggio
Three Astro-Arcades developed with to play with astrophysics
Full text linkDuring "Time Machines", a pop exhibition at Palazzo Esposizioni Roma, in Italy (Nov 2023 - March 2024) celebrating the wonders of the Universe, we feature interactive displays and activities to explore the mysteries of space and time, including an actual arcade with 80s-style video games.
Three arcade-style video games were created using Scratch, a block-based visual programming language aimed primarily at children, developed by MIT: Asteronoids, Planetris, and AstroPacman. The poster was selected and presented at the Communicating Astronomy with the Public (CAP) Conference, the only large-scale, international conference for astronomy communication (June 24-28 2024)
Strategie di comunicazione su TikTok per “Macchine del Tempo”, la mostra dell’INAF: numeri e risultati
Full text linkDal 12 gennaio 2024 al 20 marzo 2024, la comunicazione dedicata alla mostra INAF “Macchine del Tempo” si è aperta anche a TikTok sul profilo di Media INAF. Sono stati pubblicati 12 video dedicati alla mostra INAF che hanno generato migliaia di visualizzazioni e interazioni. Secondo il Rapporto Digital 2024, 43 milioni di persone in Italia sono attive sui social e TikTok è l’app che colleziona più ore di visualizzazione discostandosi molto da social come YouTube, Facebook e Instagram. Per questo motivo, tra le varie strategie social ideate per far conoscere la mostra dell’INAF “Macchine del Tempo” abbiamo deciso di sfruttare le potenzialità di questo social così dinamico, quanto controverso.
In questo report pubblichiamo i risultati prodotti da questa prima sperimentazione di campagna social
Precise characterisation of HD 15337 with CHEOPS: A laboratory for planet formation and evolution
Full text linkContext. The HD 15337 (TIC 120896927, TOI-402) system was observed by the Transiting Exoplanet Survey Satellite (TESS), revealing the presence of two short-period planets situated on opposite sides of the radius gap. This offers an excellent opportunity to study theories of formation and evolution, as well as to investigate internal composition and atmospheric evaporation. Aims: We aim to constrain the internal structure and composition of two short-period planets situated on opposite sides of the radius valley: HD 15337 b and c. We use new transit photometry and radial velocity data. Methods: We acquired 6 new transit visits with the CHaracterising ExOPlanet Satellite (CHEOPS) and 32 new radial velocity measurements from the High Accuracy Radial Velocity Planet Searcher (HARPS) to improve the accuracy of the mass and radius estimates for both planets. We re-analysed the light curves from TESS sectors 3 and 4 and analysed new data from sector 30, correcting for long-term stellar activity. Subsequently, we performed a joint fit of the TESS and CHEOPS light curves, along with all available RV data from HARPS and the Planet Finder Spectrograph (PFS). Our model fit the planetary signals, stellar activity signal, and instrumental decorrelation model for the CHEOPS data simultaneously. The stellar activity was modelled using a Gaussian-process regression on both the RV and activity indicators. Finally, we employed a Bayesian retrieval code to determine the internal composition and structure of the planets. Results: We derived updated and highly precise parameters for the HD 15337 system. Our improved precision on the planetary parameters makes HD 15337 b one of the most precisely characterised rocky exoplanets, with radius and mass measurements achieving a precision better than 2% and 7%, respectively. We were able to improve the precision of the radius measurement of HD 15337 c to 3%. Our results imply that the composition of HD 15337 b is predominantly rocky, while HD 15337 c exhibits a gas envelope with a mass of at least 0.01 M⊕. Conclusions: Our results lay the groundwork for future studies, which can further unravel the atmospheric evolution of these exoplanets and offer new insights into their composition and formation history as well as the causes behind the radius gap. The data are available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/686/A282 This article uses data from CHEOPS programme CH_PR100031. Based on observations made with ESO-3.6 m telescope at the La Silla Observatory under programme ID 1102.C-0923