Calendar

Astronomy is in a Golden Age. Ambitious surveys such as COSMOS are possible only because we have three Great Observatories operating at once – Chandra, Hubble and Spitzer – spanning the electromagnetic spectrum. COSMOS-Legacy illustrates how tightly connected these bands are. But Golden Ages are short, or they wouldn’t be golden. Our Golden Age may end because our telescopes grow exponentially in cost and have reached the point where the next step is unaffordable. In the age of JWST, will we have to wait a decade or more to have complementary X-ray observations? I discuss 3 responses to this looming crisis (other than giving up!). The third response is generational in timescale but offers open-ended growth: the harnessing of space resources. Astronomers can help this era come about by re-starting “Applied Astronomy”. Then we will be able to surpass COSMOS-Legacy.

Brown dwarfs – objects intermediate in mass between stars and planets – are ideal benchmark objects to test theories of star and planet formation. In particular, we hope to contribute to the understanding of the Initial Mass Function, the evolution of disks, and the physics of accretion. In this talk I will present results from a variety of observational studies focused on young brown dwarfs. I will show recent findings from our brown dwarf survey SONYC (Substellar Objects in Nearby Young Cluster), from IR and submm/mm observations of brown dwarf disks, and from variability studies aimed to constrain magnetic activity and accretion.

Active star formation was originally identified by optical variability. Nonetheless constraints on telescope time and limitations in capability generally limited observations of young stars to single spectral observations and optical photometric monitoring. This has led to our current picture of star formation of rotating spotted star surrounded by a static disk. I discuss recent near and mid infrared observations which demonstrate that the disk is highly dynamic with periodic structure which appear to be related with both stellar rotation and circumstellar revolutionary times scales. In our JHK study of Orion we find periods for hundreds of Class I and Class II objects and demonstrate complex changes in disk structure. Mid-IR observations show significant variability as well. Finally I discuss the first X-ray observation of a planetary transit. We demonstrate the X-ray radius is significantly greater than the optical extent.

In questa tesi si parla di Astronomia Gamma e, in particolare, della descrizione di un simulatore che determina l’efficienza quantica del fotomoltiplicatore al Silicio (SiPM) montato sul telescopio prototipo ASTRI SST-2M. Le sorgenti VHE vengono osservate dal suolo, sfruttando il fenomeno della radiazione Cherenkov. I telescopi gia` attivi per queste osservazioni sono gli IACT, Imaging Atmospheric Cherenkov Telescopes. Di futura generazione e’, invece, il CTA, Cherenkov Telescopes Array, con il quale si prevede di raggiungere un’energia di soglia di 1 Tev. L’Italia sta collaborando alla sua costruzione con il progetto ASTRI, realizzando un prototipo per i Small Size Telescopes (SST). Il prototipo monta sul piano focale un rivelatore al Silicio per il quale e’ stata condotta una simulazione che restituisce l’efficienza quantica (PDE) del dispositivo. Dal momento che la casa costruttrice non forniva le dimensioni del fotomoltiplicatore, sono state prodotte diverse curve di PDE, al variare delle dimensioni del SiPM e dell’overvoltage a cui opera. L’aderenza con i dati sperimentali, rilevati dal laboratorio COLD dell’Osservatorio Astronomico di Catania, e’ stata verificata con il test del chi quadro.

Young stars are known to be variable sources both in optical, infrared, and X-ray. This variability is strictly correlated with their physical properties and the morphology of the circumstellar material, if any. The study of their light curves and the connection between the observed variability in the various regions of the electromagnetic spectrum provides a deep insight on the physical properties and evolutionary status of young stars, both with and without disks. This motivated the Coordinated Synoptic Investigation of the young open cluster NGC~2264 (CSI 2264, Cody et al. 2014, Stauffer et al. 2014). This project is an unique and unprecedented cooperative project involving simultaneous observations with 15 ground and space telescopes, and covering a wide part of the electromagnetic spectrum from X-ray to mid-infrared. In this talk I will compare the optical and X-ray variability of NGC 2264 candidate members using simultaneous observations taken with the Convection, Rotation and Planetary Transits satellite (CoRoT), and Chandra/ACIS-I. I will show that a significant correlation between the flux variability in optical and X-ray is observed among the stars with disk where the central star is periodically or irregularly obscured by material associated with the circumstellar disk, and that in some of these sources an increase of the hydrogen column nH is observed during the obscuration observed in optical. In more than 50\% of the disk-less objects the optical and X-ray flux variability are anticorrelated, in about 25% they are correlated, while the remainder do not show any correlation between the variability in the two bands. I will discuss how the distribution of spots in the photosphere and active regions in the stellar coronae, inclination of the rotational axis, and rotational period may influence this result.

Secondary eclipse observations allow the characterisation of the dayside of hot Jupiter exoplanet atmospheres. The standard, state of the art way of getting these observations is by using IRAC on the Spitzer Space Telescope. This instrument was not designed to reach the precision required to conduct these observations. However, it is possible to push IRAC to detect the secondary eclipse. It has been used for nearly 10 year to observe secondary eclipses of a handful of exoplanets. The data are strongly affected by systematic errors which can limit the accuracy that we can measure the depth of the eclipse, as well as other parameters that can be derived from the lightcurve. In this talk I discuss the way that the WASP group analyses these data and describe a method of signal injection that can help in determining more realistic error bars on the time of mid eclipse and the eclipse depth. The two are fundamental parameters that come out of these observations. I also describe the work I would like to conduct as a postdoctoral research assistant once I have completed my PhD.

Il restauro e la conservazione dei beni librari ed archivistici sono stati considerati per molto tempo attivita` da espletare solo in laboratorio e quasi esclusivamente a vantaggio dei pezzi piu` preziosi, importanti o rappresentativi delle collezioni. Negli ultimi anni invece si sono affermate attivita` di conservazione che beneficino un grande numero di beni. Si e`, inoltre, finalmente imposta l’idea che il conservatore-restauratore e` una figura che debba occuparsi della salvaguardia delle collezioni ad ampio spettro, prendendosi cura anche della manipolazione, della movimentazione, degli ambienti di conservazione e della musealizzazione. In quest’ottica il tirocinio pratico Corso di Laurea abilitante in Conservazione e Restauro dei Beni Culturali, ha previsto un cantiere presso la Biblioteca ed Archivio Storico dell’I.N.A.F – Osservatorio Astronomico di Palermo. Il patrimonio storico di questa istituzione conta un’importante collezione bibliografica, iniziata dal fondatore (G. Piazzi) e arricchita dai vari direttori ad esso succedutisi, un ricchissimo archivio che raccoglie la documentazione non soltanto amministrativa dell’osservatorio ed anche una preziosa raccolta fotografica di positivi e negativi ancora in parte da esplorare.

A solar eruption after a flare on 2011 June 7 produced EUV-bright impacts of fallbacks far from the eruption site, observed with the Solar Dynamics Observatory. These impacts can be taken as a template for the impact of stellar accretion flows. Broad redshifted UV lines have been commonly observed in young accreting stars. Here we study the emission from the impacts in the Atmospheric Imaging Assembly’s UV channels and compare the inferred velocity distribution to stellar observations. We model the impacts with two-dimensional hydrodynamic simulations. We find that the localized UV 1600 A emission and its timing with respect to the EUV emission can be explained by the impact of a cloud of fragments. The first impacts produce strong initial upflows. The following fragments are hit and shocked by these upflows. The UV emission comes mostly from the shocked front shell of the fragments while they are still falling, and is therefore redshifted when observed from above. The EUV emission instead continues from the hot surface layer that is fed by the impacts. Fragmented accretion can therefore explain broad redshifted UV lines (e.g., C IV 1550 A) to speeds around 400 km/s observed in accreting young stellar objects.

In this talk I want to report on my research activity during the past two years at INAF-OAPa, which has been focused on the study of systems with hot Jupiters. In particular, I will show how hot Jupiters can affect the activity of their host stars, in two examples: HD 189733 and WASP-18. I will briefly report on results from another couple of systems with planets in eccentric orbits. In addition, I will mention other results from the study of star forming regions and the search in X-rays of low mass companions to Cepheids.