LA DIGITALIZZAZIONE PER LA DOCUMENTAZIONE, LO STUDIO E LA FRUIZIONE DI UN SITO ARCHEOLOGICO. LA VR EXPERIENCE DEL TEATRO DI RICINA

This paper presents a workflow developed thanks to the collaboration between archae- ologists and engineers, aimed at the documentation, representation and virtual fruition of an archaeological site. The purpose is to exploit the data acquired through digital solutions and the consequent elaboration of a reality 3D model to support archaeological studies and to effectively disseminate their results. The presented case study is the Roman Theatre of Ricina (Villa Potenza, MC). The building has preserved much of its masonry, but it is very different from that which could be appreciated by the audience of theatrical performances in Roman times. The work has been developed according to three steps: 1) digital documentation of the site and elaboration of a reality-based 3D model; 2) study of the archaeological finds thanks to the reality-based 3D model and design of a possible reconstruction, represented through a second 3D model elaborated by anastylosis; 3) development of a Virtual Reality environment for the fruition and the interaction with the two 3D models. The final output is therefore an immersive VR application that offers the possibility to access to the theatre both in its current form and in the original one. An experience that is not limited to a simple visualization rather presenting itself as a guided tour across the centurie

A Keplerian Disk around the Herbig Ae star HD169142

We present Submillimeter Array observations of the Herbig Ae star HD169142 in 1.3 millimeter continuum emission and 12CO J=2-1 line emission at 1.5 arcsecond resolution that reveal a circumstellar disk. The continuum emission is centered on the star position and resolved, and provides a mass estimate of about 0.02 solar masses for the disk. The CO images show patterns in position and velocity that are well matched by a disk in Keplerian rotation with low inclination to the line-of-sight. We use radiative transfer calculations based on a flared, passive disk model to constrain the disk parameters by comparison to the spectral line emission. The derived disk radius is 235 AU, and the inclination is 13 degrees. The model also necessitates modest depletion of the CO molecules, similar to that found in Keplerian disks around T Tauri stars.Comment: 10 pages, 2 figures, accepted by A

Organic Molecules and Water in the Inner Disks of T Tauri Stars

We report high signal-to-noise Spitzer IRS spectra of a sample of eleven classical T Tauri stars. Molecular emission from rotational transitions of H2O and OH and ro-vibrational bands of simple organic molecules (CO2, HCN, C2H2) is common among the sources in the sample. The gas temperatures (200-800 K) and emitting areas we derive are consistent with the emission originating in a warm disk atmosphere in the inner planet formation region at radii < 2 AU. The H2O emission appears to form under a limited range of excitation conditions, as shown by the similarity in relative strengths of H2O features from star to star and the narrow range in derived temperature and column density. Emission from highly excited rotational levels of OH is present in all stars; the OH emission flux increases with the stellar accretion rate, and the OH/H2O flux ratio shows a relatively small scatter. We interpret these results as evidence for OH production via FUV photo-dissociation of H2O in the disk surface layers. No obvious explanation is found for the observed range in the relative emission strengths of different organic molecules or in their strength with respect to water. We put forward the possibility that these variations reflect a diversity in organic abundances due to star-to-star differences in the C/O ratio of the inner disk gas. Stars with the largest HCN/H2O flux ratios in our sample have the largest disk masses. We speculate that such a trend could result if higher mass disks are more efficient at planetesimal formation and sequestration of water in the outer disk, leading to enhanced C/O ratios and abundances of organic molecules in the inner disk. A comparison of our derived HCN to H2O column density ratio to comets, hot cores, and outer T Tauri star disks suggests that the inner disks are chemically active.Comment: Accepted for publication in The Astrophysical Journa

Optical and Radio monitoring of S5 1803+74

The optical (BVRI) and radio (8.4 GHz) light curves of S5 1803+784 on a time span of nearly 6 years are presented and discussed. The optical light curve showed an overall variation greater than 3 mag, and the largest changes occured in three strong flares. No periodicity was found in the light curve on time scales up to a year. The variability in the radio band is very different, and shows moderate oscillations around an average constant flux density rather than relevant flares, with a maximum amplitude of $\sim$30%, without a simultaneous correspondence between optical and radio luminosity. The optical spectral energy distribution was always well fitted by a power law. The spectral index shows small variations and there is indication of a positive correlation with the source luminosity. Possible explanations of the source behaviour are discussed in the framework of current models.Comment: 25 pages, 12 figure

Resolving Molecular Line Emission from Protoplanetary Disks: Observational Prospects for Disks Irradiated by Infalling Envelopes

Molecular line observations that could resolve protoplanetary disks of ~100 AU both spatially and kinematically would be a useful tool to unambiguously identify these disks and to determine their kinematical and physical characteristics. In this work we model the expected line emission from a protoplanetary disk irradiated by an infalling envelope, addressing the question of its detectability with subarcsecond resolution. We adopt a previously determined disk model structure that gives a continuum spectral energy distribution and a mm intensity spatial distribution that are consistent with observational constraints of HL Tau. An analysis of the capability of presently working and projected interferometers at mm and submm wavelengths shows that molecular transitions of moderate opacity at these wavelengths (e.g., C17O lines) are good candidates for detecting disk lines at subarcsecond resolution in the near future. We suggest that, in general, disks of typical Class I sources will be detectable.Comment: 41 pages, 16 figures. To be published in The Astrophysical Journa

A New Probe of the Planet-Forming Region in T Tauri Disks

We present new observations of the FUV (1100-2200 Angstrom) radiation field and the near- to mid-IR (3--13.5 micron) spectral energy distribution (SED) of a sample of T Tauri stars selected on the basis of bright molecular disks (GM Aur, DM Tau, LkCa15). In each source we find evidence for Ly alpha induced H2 fluorescence and an additional source of FUV continuum emission below 1700 Angstroms. Comparison of the FUV spectra to a model of H2 excitation suggests that the strong continuum emission is due to electron impact excitation of H2. The ultimate source of this excitation is likely X-ray irradiation which creates hot photo-electrons mixed in the molecular layer. Analysis of the SED of each object finds the presence of inner disk gaps with sizes of a few AU in each of these young (~1 Myr) stellar systems. We propose that the presence of strong H2 continuum emission and inner disk clearing are related by the increased penetration power of high energy photons in gas rich regions with low grain opacity.Comment: 5 pages, 3 figures, accepted by ApJ Letter

Optical and infrared observations of the supernova SN 1999el

Optical and near-infrared light curves of the Type IIn supernova 1999el in NGC 6951 are presented. A period of 220 days (416 days in the near-infrared) is covered from the first observation obtained a few days before maximum light. Spectroscopic observations are also discussed. Using as a distance calibrator the Type Ia SN 2000E, which occurred some months later in the same galaxy, and fitting a blackbody law to the photometric data we obtain a maximum bolometric luminosity for SN 1999el of $\sim 10^{44}$ erg s$^{-1}$. In general, the photometric properties of SN 1999el are very similar to those of SN 1998S, a bright and well studied Type IIn SN, showing a fast decline in all observed bands similar to those of Type II-L SNe. The differences with SN 1998S are analyzed and ascribed to the differences in a pre-existing circumstellar envelope in which dust was already present at the moment of the SN outburst. We infer that light echoes may play a possibly significant role in affecting the observed properties of the light curves, although improved theoretical models are needed to account for the data. We conclude that mass loss in the progenitor RG stars is episodic and occurs in an asymmetric way. This implies that collapsing massive stars appear as normal Type II SN if this occurs far from major mass loss episodes, whereas they appear as Type IIn SNe if a large mass loss episode is in progress.Comment: 30 pages, 8 figures, figure 1 available as jpeg file, ApJ in pres

Spitzer Space Telescope study of disks in the young σ\sigma Orionis cluster

We report new Spitzer Space Telescope observations from the IRAC and MIPS instruments of the young (~ 3 Myr) sigma Orionis cluster. We identify 336 stars as members of the cluster using optical and near-infrared color magnitude diagrams. Using the spectral energy distribution (SED) slopes in the IRAC spectral range, we place objects in several classes: non-excess stars, stars with optically thick disks(like classical T Tauri stars), class I (protostellar) candidates, and stars with ``evolved disks''; the last exhibit smaller IRAC excesses than optically thick disk systems. In general, this classification agrees with the location expected in IRAC-MIPS color-color diagrams for these objects. We find that the evolved disk systems are mostly a combination of objects with optically thick but non-flared disks, suggesting grain growth and/or settling, and transition disks, systems in which the inner disk is partially or fully cleared of small dust. In all, we identify 7 transition disk candidates and 3 possible debris disk systems. As in other young stellar populations, the fraction of disks depends on the stellar mass, ranging from ~10% for stars in the Herbig Ae/Be mass range (>2 msun) to ~35% in the T Tauri mass range (1-0.1 msun). We find that the disk fraction does not decrease significantly toward the brown dwarf candidates (<0.1 msun). The IRAC infrared excesses found in stellar clusters and associations with and without central high mass stars are similar, suggesting that external photoevaporation is not very important in many clusters. Finally, we find no correlation between the X-ray luminosity and the disk infrared excess, suggesting that the X-rays are not strongly affected by disk accretion.Comment: 44pages, 17 figures. Sent to Ap

Diseño y Construcción de un Convertidor Boost de Pequeña Potencia, con PropósitosEducativos y de Investigación

This paper presents the design and construction of a DC-DC boost converter for a nominal power of 200W, with an input voltage of 100V and an output voltage of 200V, on the basis of theoretical analysis with the aim of design and determine all the components associated with the mentioned converter. In this research we use the voltage feedback control with a PI controller tuned by pole placement, and a PWM modulator for the IGBT switching. The converter performance and the control system faced with step changes in the input voltage and the load resistance is verified through computer simulation and then verified by experimental tests using a microcontroller PIC16F877.Este articulo presenta el diseño y construcción de un convertidor DC-DC boost o elevador de tensión, para una potencia nominal de 200 W, con una tensión de entrada de 100 V y una tensión de salida de 200 V, basándose previamente en un análisis teórico del mismo para así diseñar y determinar todos los componentes asociados a dicho convertidor. En este artículo se utiliza el control por retroalimentación de voltaje con un controlador PI, sintonizado mediante la asignación de polos, además de un modulador PWM (Pulse Width Modulation) para la conmutación del IGBT (Insulated Gate Bipolar Transistor). El desempeño del convertidor y del sistema de control ante cambios de tipo escalón en el voltaje de entrada y resistencia carga, es verificado a través de simulación computational y luego comprobado mediante pruebas experimentales utilizando un microcontrolador PIC16F877

Interseismic quiescence and triggered slip of active normal faults of Kīlauea Volcano's south flank during 2001-2018

The mobile south flank of Kīlauea Volcano hosts two normal fault systems, the Koa'e fault system (KFS) and the Hilina fault system (HFS). In historical time, at least three M>6.5 earthquakes have occurred on the basal detachment of the Kīlauea Volcano's south flank, with the most recent being the 4 May 2018 M6.9 earthquake. Here we analyze kinematic Global Positioning System data collected from 2001 to 2017 and interferometric synthetic aperture radar data before, during, and after the 2018 M6.9 earthquake to determine the crustal motion across the HFS and KFS faults. Our results indicate that the HFS faults did not significantly slip during the interseismic period from 2007 to 2011. Despite its substantial magnitude, interferometric synthetic aperture radar (InSAR) data show that the 2018 M6.9 earthquake triggered subcentimeter level slip along sections of the previously mapped HFS branches. Up to 20 cm of offset occurred on what appears to be a newly formed (or previously unknown) fault near the eastern end of the HFS. During the 3 months following the M6.9 earthquake, up to ~30 cm of slip occurred along the KFS, which helps accommodate rapid large‐scale subsidence of Kīlauea's summit region as large volumes of summit reservoir magma fed the lower East Rift Zone eruption. The HFS appears to activate only in concert with large earthquakes on the basal detachment. The KFS, on the other hand, moves both seismically during small local earthquakes and aseismically in response to nearby earthquakes and caldera subsidence