In 2018 and 2019, Seminars at IAPS are organized by:
Alessandra Derosa, Anna Milillo, Sergio Molinari.
———————– YEAR 2019 ———————–
30-01-2019, 14:00, Aula IB09, ARTOV – IAPS – Via Fosso Del Cavaliere, 100
The Key Science Projects of the Cherenkov Telescope Array
Stefano Vercellone – INAF/OABrera, Brera
The Cherenkov Telescope Array (CTA) will be the next generation gamma-ray observatory, open to the scientific community, to investigate the very high-energy emission from a large variety of celestial sources in the 20 GeV – 300 TeV energy range. The full array, distributed over two sites, one in the northern and one in the southern hemisphere, will provide whole-sky coverage and will improve the sensitivity with respect to the current major arrays such as H.E.S.S., MAGIC and VERITAS by a factor of five to twenty, depending on the energy. CTA will investigate a much higher number of already known classes of sources, going to much larger distances in the Universe, performing population studies, accurate variability and spatially-resolved studies.
We review the current status of the CTA project and discuss the main CTA Key Science Projects, which will focus on major scientific cases, allowing us to provide legacy data-sets of high value to a wider community in a context of synergies with other major multi-wavelength facilities.
23-01-2019, 14:00, Aula IB09, ARTOV – IAPS – Via Fosso Del Cavaliere, 100
To be defined
Elisabetta Dotto – INAF- OARoma, Monteporzio
16-01-2019, 14:00, Aula IB09, ARTOV – IAPS – Via Fosso Del Cavaliere, 100
La missione BepiColombo e la strumentazione italiana a bordo
A cura del gruppo di divulgazione Bep-it!
BepiColombo, durante la sua crociera di 7 anni, viaggerà in maniera “compatta”: un motore elettrico (MTM) spingerà il satellite europeo MPO e giapponese MMO, in una “pila” di più di 6 metri. Il modulo Europeo, in particolare, avrà a bordo 11 strumenti, 4 dei quali saranno “made in Italy” (e tre di essi a forte partecipazione IAPS): la suite di 4 sensori SERENA che studieranno l’esosfera e la sua interazione con la superficie, la magnetosfera e il vento solare; la suite di 3 strumenti ottici SIMBIO-SYS che forniranno immagini della superficie del pianeta sia in 2D sia in 3D, indicandone anche la composizione; ISA che misurerà le accelerazioni non gravitazionali e che sarà di supporto a MORE nella stima del campo di gravità di Mercurio, dando informazioni preziose sul suo interno, e nei test della teoria della relatività di Einstein.
———————– YEAR 2018 ———————–
12-12-2018, 14:30, Aula IB09, ARTOV – IAPS – Via Fosso Del Cavaliere, 100
Stellar Activity and exoplanets: the Sun’s lesson
Francesco Berrilli (Università degli Studi di Roma Tor Vergata)
The solar atmosphere, acting as a nonlinear dissipative system subjected to an external forcing (i.e. non zero energy flow), presents a state of reduced symmetry with the consequent formation of convective and magnetic structures and evolution of associated patterns. These magneto-convective structures, modulated by the global dynamo, interact with the hosted planets and impact the climate and habitability of terrestrial (exo)planets. Innovative spectral proxies of solar activity and planetary climatic response may be useful for application to observational surveys of UV activity in Sun-like stars and IR signal in exoplanetary systems.
28-11-2018, 14:00-14:50, Aula IB09, ARTOV – IAPS – Via Fosso Del Cavaliere, 100
Che cosa è e come funziona l’Ufficio Comunicazione INAF per la Didattica e la Divulgazione
Stefano Sandrelli (INAF, Osservatorio di Brera)
Dal maggio 2016, la Presidenza INAF si e’ dotata di una struttura per la Comunicazione che coordina le azioni di Didattica e Divulgazione dell’ente, cercando di valorizzare sempre di piu’ le strutture sul territorio e la componente di ricerca. Vediamo insieme con quali strumenti, quali strategie, quale visione e quali prospettive per il futuro.
28-11-2018, 14:50-15:15, Aula IB09, ARTOV – IAPS – Via Fosso Del Cavaliere, 100
Presentazione attività di Didattica e Divulgazione IAPS
Livia Giacomini (INAF – IAPS)
Verranno illustrate le principali attività di didattica e divulgazione organizzate dall’Ufficio di Comunicazione INAF-IAPS e le possibilità di collaborare con noi. Partendo dal nostro nuovo sito (www.iaps.inaf.it/ufficio.comunicazione), verranno presentati i progetti dedicati alle scuole e le possibili partecipazioni a eventi e manifestazioni divulgative. Saranno infine illustrati i due nuovi progetti Pianeti in una stanza e il MUVISS, il Museo Virtuale delle Scienze Spaziali.
28-11-2018, 15:15-15:30, Aula IB09, ARTOV – IAPS – Via Fosso Del Cavaliere, 100
Presentazione Olimpiadi di Astronomia
Fiamma Capitanio (INAF – IAPS)
Le Olimpiadi Italiane di Astronomia, con il pretesto della competizione, offrono agli studenti delle scuole italiane un’occasione di confronto con altri ragazzi e la possibilità di coltivare l’interesse e la passione per l’astronomia (materia poco studiata nelle scuole superiori). Inoltre i ragazzi che vi partecipano hanno l’occasione di incontrare e conoscere il mondo della ricerca scientifica. Illustrerò brevemente l’organizzazione delle Olimpiadi Italiane di Astronomia e il coinvolgimento del nostro istituto sia a livello locale che nazionale.
21-11-2018, 11:00, aula Convegni, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
The quest for single and dual active galactic nuclei: a numerical perspective
Pedro Capelo (University of Zurich)
Supermassive black holes (SMBHs) are believed to lie at the centre of most galaxies and to coevolve with them, growing through both mergers and accretion, shining as active galactic nuclei (AGN), and feeding part of the accretion energy back to their hosts. When galaxies merge, SMBHs may reveal themselves as dual AGN and, much later in the merging process, as gravitational-wave sources. I address a variety of questions, related to both dynamics and growth of SMBHs, by using high-resolution, N-body, hydrodynamical simulations of mergers between late-type galaxies, in which I vary mass ratios, gas fractions, orbital configurations, and SMBH masses, and where I include realistic descriptions of cooling, stellar and SMBH feedback, and star formation. In this talk, I will mostly focus on examining which mergers preferentially trigger AGN activity, distinguishing between merger-related and secular-related accretion, tracing the resultant evolution of the SMBH mass ratios in the pairing process, describing different gas feeding paths, and connecting theory with observations in the search for dual AGN.
07-11-2018, 11:00, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
High-contrast imaging observations of exoplanetary systems: current status and future perspectives
Valentina D’Orazi (INAF/OAPadova, Padova)
Thanks to notable advancements in adaptive optics combined with coronagraphic observational strategies, high-contrast imaging techniques are rapidly progressing in the current years. The exploration of the sub-stellar regime via direct imaging, hampered so far by technical limitations, is starting to provide us with a powerful tool. SPHERE at VLT, combining extreme adaptive optics with coronagraphy, dual-band imaging and integral field spectroscopy, has started its operations: relatively massive exoplanets at few tenths of arcsecond separations and contrasts better than 106 can be reached. In this contribution I will present recent results obtained with SPHERE in the framework of the SHINE survey. Moreover, I will present a new system for coronagraphy with high-order adaptive optics that will be operating at LBT by the end of 2019: SHARKs. This system will provide coronagraphic observations from visual to NIR bands, allowing a spectral coverage that is not currently available for any other instrument in the world. Finally, I will discuss the employment of a brand-new technique that combines highcontrast imaging with high-dispersion spectroscopy, allowing in principle to reach contrasts down to 1010. In the era of E-ELT, this will open the way to investigating earth-like planets in the habitable zones of their parent stars.
31-10-2018, 11:00, aula Convegni, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Unveiling the Obscured Universe with SPICA observations
Luigi Spinoglio (INAF/IAPS Roma)
A most exciting but still unknown process in modern astrophysics is how galaxy evolution develops from the last ten billion years. Star formation (SF) and accretion onto supermassive black holes (BHA) play this game. Around the peak of the SF and BHA rate histories (z=1-4), galaxies and stars develop in dusty heavily obscured environments, preventing optical/UV observations to reveal their nature. As opposite, IR spectroscopy (and photometry at higher redshift) will reveal physically galaxy evolution, allowing to measure through lines the main physical properties (e.g., ionization field, density, metallicity, gas velocities, etc.). I will show how the ESAJAXA (preselected in M5) mission SPICA will do this.
Also unknown, because deeply obscured by interstellar dust, is the early evolution of stars and planets, which will strongly benefit from key observations that only SPICA will be able to do. I will also outline the IR spectroscopy of proto-planetary disks and protostellar objects and FIR polarimetric images of interstellar filaments, to give a few examples.
24-10-2018, 11:00, Aula Convegni, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
The search for life elsewhere
Daniela Billi (Università di Tor Vergata, Roma)
Are we alone in the Universe? Clues to address this question derive from disparate disciplines, from the most hostile places on Earth, from the experiments carried out in research laboratories and outside the International Space Station, as well as from the space missions that study comets and asteroids.
10-10-2018, 11:00, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Supermassive black holes and planetary habitability
Amedeo Balbi (Università di Tor Vergata, Roma)
It is generally thought that the habitability of a planet is strongly influenced by the amount of ionizing radiation incident on its atmosphere and surface. While the host star is usually the prevalent origin of such high-energy radiation, previous studies have also considered the effect on a hypothetic biosphere of other possible sources, in particular with regard to potentially catastrophic transient events such as nearby gamma ray bursts or supernova explosions. Here we consider a phenomenon whose astrobiological consequences are much less explored, i.e. the production of X-ray and extreme ultraviolet (XUV) radiation during the peak of the active phase of supermassive black holes. In particular, we investigated how the activity of the supermassive black hole at the center of the Milky Way, known as Sagittarius A* (Sgr A*), may have affected the habitability of Earthlike planets in our Galaxy. Our results show for the first time that the combined effect of atmospheric loss and of the direct biological damage to surface life was probably significant during the AGN phase of Sgr A*, possibly hindering the development of complex life within a few kiloparsecs from the galactic center.
04-10-2018, 14:30, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Turbulence: the last unsolved problem of classical physics
Vincenzo Carbone (Università della Calabria, Cosenza)
Since the early ‘500, the problem of turbulence in fluid flows has been posed to the attention of scientists. Although a lot of efforts have been devoted to solve the problem, both from a mathematical and physical point of view, some basic aspect of turbulent fluid flows yet remains somewhat wrapped in mystery. The advent of space flights and high performance computers provided a lot of new experimental evidences and, in some sense, further complications in the theory. The talk provides an up to date short review of this last
unsolved problem of classical physics.
26-09-2018, 11:00, Aula Convegni, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Radar evidence of subglacial liquid water on Mars
Roberto Orosei (INAF – Istituto di Radioastronomia)
The presence of liquid water at the base of the Martian polar caps has long been suspected but not observed. We surveyed the Planum Australe region using the Mars Advanced Radar for Subsurface and Ionosphere Sounding, a low-frequency radar on the Mars Express spacecraft. Radar profiles collected between May 2012 and December 2015, contain evidence of liquid water trapped below the ice of the South Polar Layered Deposits. Anomalously bright subsurface reflections were found within a well-defined, 20km wide zone centered at 193°E, 81°S, surrounded by much less reflective areas. Quantitative analysis of the radar signals shows that this bright feature has high dielectric permittivity >15, matching water-bearing materials. We interpret this feature as a stable body of liquid water on Mars.
19-09-2018, 11:00, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Detection of the Missing Baryons in the Warm-Hot Intergalactic Medium
Fabrizio Nicastro (INAF – Ossrvatorio Astronomico di Roma)
It has been known for decades that the observed number of baryons in the local Universe falls about 30-40% short of the total number of baryons predicted by Big-Bang Nucleosynthesis, inferred by density fluctuations of the Cosmic Microwave Background and seen during the first 2-3 billion years of the universe (redshift z>2-3) in the so called “Lyman-α Forest”. While theory provides a reasonable solution to this paradox, by locating the missing baryons in hot and tenuous filamentary gas connecting galaxies, it also sanctions the difficulty of detecting them because their by far largest constituent, hydrogen, is mostly ionized and therefore virtually invisible in ordinary signal-to-noise Far-Ultraviolet spectra. Indeed, despite the large observational efforts, only a few marginal claims of detection have been made so far.
Here I will first review the observational efforts pursued over the past 15 years by several groups and will then present our recent results that show that the missing baryons are indeed found in a tenuous warm-hot and moderately enriched medium that traces large concentrations of galaxies and permeates the space between and around them. I will show that the number of OVII systems detected down to the sensitivity threshold of our data, agrees well with numerical simulation predictions for the long-sought hot intergalactic medium, and its detection adds a fundamental tile to the long-standing missing baryon puzzle. Finally, I will comment on the implications of these new results for future high resolution X-ray missions (e.g. Athena).
17-09-2018, 11:00, Aula Gratton, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
The peculiar case of the active galactic nucleus in PBC J2333.9-2343
Lorena Hernandez (Euniversity of VALPARAISO – CHILE)
Under unification schemes, active galactic nuclei (AGN) can be explained by orientation effects. However, some sources show properties at different frequencies that led to incongruent classifications and cannot be explained by such unification scheme. This is the case of PBC J2333.9-2343; its optical spectrum is of a type 2 AGN but its X-ray spectrum does not show signs of absorption, and in the radio it has many features typical of a blazar but it is a giant radio galaxy. Using multiwavelength simultaneous data from XMM-Newton, San Pedro Mártir telescope and VLBA, we find that these classifications cannot be attributed to variability. We propose that PBC J2333.2343 is a blazar that has undergone a restarting activity episode in its nucleus. Interestingly, it has changed from being a radio galaxy to become a blazar, showing an exceptional change in the direction of the jet that, by chance, occurred in the plane of the sky.
Moreover, we have analyzed Swift and New Technology Telescope (NTT) data to study the variability of the source, revealing a change in the broad line region BLR) clouds and increasing variability at all observed wavelengths and we have detected an outflow in its optical spectra.
12-09-2018, 11:00, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
The Milky Way in motion
Ronald Drimmel (INAF – Ossrvatorio Astrofisico di Torino)
Thanks to the most recent data release from ESA’s Gaia satellite, the astronomical community now has at its finger tips the parallaxes and proper motions of over a billion stars. While this represents only a tiny fraction of the total number of stars in our galaxy, it samples a significant fraction of the volumn of the Milky Way. Gaia is not only a galactic cartographers dream machine: thanks to its proper motions it is setting the Galaxy in motion for us. For the first time we are able to map in detail the stellar kinematics not only in the solar neighborhood, but also in other neighboring volumns to significant distances. I present some of the most recent surprises that this data set has revealed regarding the dynamics of the Milky Way, some remaining open questions, and how Gaia is allowing us to see our home galaxy in a new light and is forcing us to rethink our usual assumptions.
31-08-2018, 11:30, Aula IB09, ARTOV- IAPS Via Fosso del Cavaliere, 100
Multiple-scale analysis of effective transport in compressible magnetohydrodynamic turbulence
Nobumitsu Yokoi (Institute of Industrial Science (IIS), University of Tokyo, Japan)
Strongly compressible magnetohydrodynamic (MHD) turbulence is investigated with the aid of the multiple-scale direct-interaction approximation, a renormalised perturbation closure scheme for inhomogeneous turbulence at very high Reynolds numbers. Turbulence correlations in the mean-field equations are evaluated with analytical expressions of the turbulent transport coefficients. It is shown that, in addition to the usual solenoidal effects, genuine compressibility effects show up in the turbulence correlation expressions, which include the density variance effects in the turbulent electromotive force, the compressive cross-helicity effects in the turbulent mass and energy fluxes, etc. Turbulence modelling based on the theoretical results is also presented. Some possible applications to shock–turbulence interaction in the context of dynamo and magnetic reconnection are discussed.
Yokoi, N. “Cross helicity and related dynamo,” Geophys. Astrophys. Fluid Dyn. 110, 114-184 (2013) doi.org/10.1080/03091929.2012.754022
Yokoi, N. “Electromotive force in strongly compressible magnetohydrodynamic turbulence,” J. Plasma Phys. 84, 1-26 (2018) doi:10.1017/S0022377818000727
27-08-2018, 11:30, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Electromotive force in space plasmas
Yasuhito Narita (Space Research Institute, Austrian Academy of Science, Graz, Austria)
Electromotive force is a cross product of fluctuations between the flow velocity and the magnetic field, and plays an important role in the dynamo mechanism.
Electromotive force is one of the second-order fluctuation quantities like fluctuation energies or elicity quantities, but has so far drawn only little attention in the observational studies in situ in the solar system plasmas. I focus on the use of electromotive force as an observational tool to study turbulence and dynamo mechanism. An analysis method is developed for the electromotive force and the transport coefficients such as those for the alpha effect and the turbulent diffusivity. A test against a magnetic cloud event in the inner heliosphere using the Helios spacecraft data is presented. The electromotive force is enhanced together with the magnetic cloud event by 1 or 2 orders of magnitude, suggesting that the magnetic field can instantly and locally be amplified in the heliosphere.
27-06-2018, 14:30, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
The OSIRIS-REx Mission: scientific outcomes from the sampling site selection
Maurizio Pajola (INAF – Osservatorio Astronomico di Padova)
The OSIRIS-REx mission is the third one in NASA’s New Frontiers Program, and its main goal is to carry home samples (2023) from the surface of 101955 Bennu, a ~500 m size B-type Near-Earth Asteroid. In December 2018, the OSIRIS-REx will finally rendezvous its target. Then, for more than 1.5 years, the entire instruments suite will be dedicated to select the best sampling site. We are deeply involved in the sampling site selection task, with the main aim of providing the boulder size-frequency distribution of the entire asteroid, the boulders localized surface densities and the boulders hazard maps of the sampling site. In addition, we will focus on the surface processes generating such sizes distributions, aiming to maximize the scientific return of the high-resolution observations. Within this talk we will first introduce the OSIRIS-REx mission, its main goals and the onboard instruments suite. Then, we will present both the expected engineering and scientific products we will prepare while riding around Bennu.
20-06-2018, 14:30, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Solar Orbiter and beyond: a new season of heliphysics studies, looking further
Daniele Spadaro (INAF – Osservatorio Astrofisico di Catania)
This is a great year for a new season of heliophysics studies, thanks to the creation of a group of Instruments, on board of space missions or steadily on earth, which will be put in operation in the next decade and will let us study our star and the heliosphere as never before.
In addition to ESA Solar Orbiter mission, whose scientific payload integration is underway and whose launch is planned in February 2020, soon (August 2018) NASA Parker Solar Probe (PSP) mission will be launched, a “mission to touch the Sun”, since the minimum distance perihelion is expected at less than 10 solar radii. On the other hand, the minimum perihelion of Solar Orbiter mission is expected at 0.28 AU, well inside Mercury orbit. The contemporary presence of both “in-situ” and “remote-sensing” instruments, in the two missions, will let us study in great details the solar processes that give birth and set the heliosphere, and then have important consequences on circumplanetary environments.
In the next decade, two big solar telescopes will be built (4 m class), the American DKIST, on the Hawaii islands, and the European EST, on the Canarian islands. They might both have the capacity to observe the solar atmosphere with a remarkable space, temporal and spectral resolution, with a great contribution to the detailed study of processes of emergence and evolution of solar magnetic fields, their role in the structure and dynamics of solar atmosphere, as well as eruptive phenomena that release great amounts of plasma in the interplanetary space. The main features of such instruments and their potential contribution to the progresses on heliophysics studies are going to be described, looking at the possibility of having new useful information concerning star physics and eso-planetary researches.
13-06-2018, 11:00. Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Preparandosi per SKA – Getting ready for the SKA
Grazia Umana (INAF – Osservatorio Astrofisico di Catania)
Lo Square Kilometre Array (SKA) è un ambizioso progetto globale di scienza e ingegneria finalizzato alla costruzione di una delle più imponenti infrastrutture astronomiche mai realizzate. Attualmente in avanzata fase di progettazione, lo SKA sarà un network di radiotelescopi, distribuito su due continenti, caratterizzato da una sensibilità mai raggiunta, da uno elevato potere risolutivo e dall’applicazione di tecnologie innovative allo sviluppo dei ricevitori, al trasporto ed elaborazione del segnale e del calcolo.
L’Italia, attraverso l’Istituto Nazionale di Astrofisica (INAF), è uno dei maggiori attori della fase di pre-costruzione, partecipando in prima linea alla progettazione, e contribuisce attivamente alla definizione dei casi scientifici attraverso gli SKA Science Working Group.
Dopo una breve illustrazione del progetto e del suo stato di avanzamento, presenterò alcune attività scientifiche preparatorie nel campo della scienza galattica che vedono alcuni team italiani protagonisti, con particolare riferimento all’Australian SKA Precursor ASKAP, attualmente in fase di Early Science.
30-05-2018, 11:00, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Research on exoplanets in Italy: current status and perspectives
Giusi Micela (INAF – Osservatorio Astronomico di Palermo)
In recent years the research on exoplanets has led to many discoveries that are allowing a better understanding of the place of the solar system in a broader astrophysical context.
The Italian scientific community has invested significantly in this field participating to the development of dedicated instruments operating both from ground and from space.
The HARPS-N spectrograph at the TNG is today the most efficient facility for the research of exoplanets through the radial velocity method. Today HARPS-N can work simultaneously with GIANO – in the GIARPS mode – observing from optical to near infrared wavelengths with performances currently unique in the world.
This, together with the participation with a leading role, to the design and exploitation of other instruments from ground and space, has allowed the development of an internationally recognized national community expert in the study of exoplanets. The future spatial missions CHEOPS, PLATO and ARIEL will give a further boost to this research for the next decades.
02-05-2018, 11:00, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Probing the innermost regions of blazar jets at tens of microarcseconds through space and millimeter VLBI observations
Jose Luis (Instituto de Astrofisica de Andalucia, Granada Spain)
Investigating how AGN jets originate, and what are the sites and mechanisms for the production of high energy emission, requires probing these jets at the highest angular resolution.
We present the results of our RadioAstron Key Science Program to study a sample of AGN jets in combination with the Event Horizon Telescope (EHT) and the GMVA. Among our earlier results,
we have successfully imaged the jet in BLLac at an angular resolution of 21 microarcseconds (uas), revealing a large scale helical magnetic field in the vicinity of the central black hole, and 0716+714 at 24 uas, showing a sharp inner bending that may be responsible for the characteristic intraday variability observed in this source. OJ287 is the best candidate for harboring a coalescing supermassive binary black hole (SMBBH) system, making it an excellent laboratory for studying strong-field relativistic effects and the future detection of nano- and mili-hertz gravitational waves. Our quasi-simultaneous RadioAstron, EHT, and GMVA observations of OJ287 reveal a highly twisted jet at an unprecedented angular resolution of 10 uas (26 Schwarzschild radii); these are analyzed in combination with our multiwavelength monitoring (optical to gamma-rays), to test the SMBBH scenario and jet formation models.
18-04-2018, 11:00, Aula Convegni, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
The realm of the first AGN in the Universe
Cristian Vignali (Dipartimento di Fisica e Astronomia – Università di Bologna)
Over the last decade, optical, near-infrared and X-ray observations have pushed the search for galaxies and AGN to very high redshifts and, coupled to mid-IR, far-IR and millimeter data, have enabled detailed studies on their physical properties and evolution.
I will present the state of the art concerning the observation and characterization of the first black holes in the Universe, including the obscured ones and the properties of their host galaxies, and the firm constraints on the low-rate mass accretion onto supermassive black holes at high redshifts as probed by the deepest X-ray exposure carried out in the Chandra Deep Field-South. I will also outline some open issues and promising prospects for the future.
04-04-2018, 11:00, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Climate models as a tool for quantifying the habitability of rocky planets
Giovanni Vladilo (INAF – Osservatorio Astronomico di Trieste)
One of the drivers of Solar System missions and exoplanet observations is the search for astronomical bodies showing signatures of life. This search poses several challenges, partly related to the definition and identification of life in the context of exobiology. In this talk I will emphasize the essential role of climate models in this type of investigation, showing how it is possible to define a quantitative index of surface habitability. I will then present a climate model developed for the study of the surface temperature of Earth-like exoplanets (Vladilo et al. 2015, ApJ 804, 50) and show an example of application of this model to a terrestrial-size exoplanet discovered with the Kepler mission (Silva et al. 2017, MNRAS, 470, 2270). Finally, I will briefly discuss the challenges that must be faced to extend the range of application of the climate-model approach to the wide spectrum of physical and chemical conditions expected to exist in rocky exoplanets.
28-03-2018, 11:00, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Astroinformatics, a data-driven Science
Massimo Brescia (INAF – Osservatorio Astronomico Capodimonte)
Astronomy has entered the big data era and Machine Learning based methods have found widespread use in a large variety of astronomical applications. This is demonstrated by the recent huge increase in the number of publications making use of this new approach. The usage of machine learning methods, however is still far from trivial and many problems still need to be solved. Through a series of astrophysical use case studies, we outline main problems and some ongoing efforts to solve them.
15-03-2018, 11:00, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Planet formation in the ALMA era
Davide Fedele (INAF – Osservatorio Astrofisico Arcetri)
Planet formation is one of the most fundamental process in modern astrophysics as it is tightly linked to the origin of life. With more than 3000 planets known so far we are learning that planetary systems are ubiquitous in the Galaxy and their architectures are highly heterogeneous. These findings challenge our understanding of the planet formation mechanism. Protoplanetary disks (a natural outcome of the star formation process) offer a unique laboratory to investigate the early phases of planet formation and evolution. A major contribution to this field is coming from the Atacama Large Millimeter Array (ALMA). For the first time indeed, we are now able to detect and spatially resolve the emission coming from the cold disk interior where planet formation takes place. I will present recent results based on ALMA observations of gas and dust in disks.
28-02-2018, 11:00, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Superfici di asteroidi: irraggiamento e micro-spettroscopia VIS-IR in laboratorio
Rosario Brunetto (Institute d’Astrophysique Spatiale, CNRS- Orsay Paris)
I materiali primitivi extraterrestri, come alcune meteoriti e le polveri di asteroidi e comete, sono caratterizzati da una grande eterogeneità di composizione a diverse scale. Questa eterogeneità è stata osservata in laboratorio con diverse tecniche. Tra queste, la micro-spettroscopia infrarossa ha il vantaggio di essere totalmente non distruttiva e consentire un confronto diretto con le osservazioni astronomiche dei corpi minori del Sistema Solare. Grazie ai recenti sviluppi dei rivelatori a matrice di tipo “Focal Plan Array”, la mappatura IR ad alta risoluzione spaziale e in tempi brevi di acquisizione e la tomografia IR sono ora possibili. In questa presentazione mostreremo alcune misure recenti di imaging spettrale FTIR su diversi materiali extraterrestri, ottenuti in collaborazione con la linea SMIS del sincrotrone SOLEIL (Francia).
Nella seconda parte presenteremo nuovi dati di imaging spettrale di meteoriti irraggiate in laboratorio con ioni a 40 keV. Questi esperimenti hanno come scopo di simulare l’irradiazione da parte del vento solare delle superfici degli asteroidi. Insieme agli evidenti effetti dell’irraggiamento misurati nelle particelle dell’asteroide Itokawa (raccolte dalla missione Hayabusa), questi risultati possono essere di supporto all’interpretazione spettrale delle osservazioni di asteroidi, per stabilire un collegamento tra asteroidi e meteoriti e per comprendere i processamenti energetici che modificano le superfici dei corpi minori. Nei campioni irraggiati in laboratorio osserviamo variazioni spettrali delle componenti organiche e minerali, nonché le variazioni dell’albedo. Questi effetti di irraggiamento in funzione della dose sono quindi confrontati su scala micrometrica con l’eterogeneità composizionale dei materiali originari, per determinare quali bande spettrali sono più sensibili agli effetti dell’alterazione energetica. I risultati saranno discussi nel contesto delle prossime missioni di raccolta di campioni asteroidali Hayabusa 2 (JAXA) e OSIRIS-REx (NASA).
25-01-2018, 11:00, Aula IB09, ARTOV – IAPS, Via Fosso Del Cavaliere, 100
Exoplanet characterisation from space and using stratospheric balloons
Enzo Pascale (Dipartimento di Fisica dell’Università di Roma, La Sapienza)
With more than 3700 exoplanets discovered to date, spectroscopic characterisation of their atmospheres is the next step. The exoplanetary science stands on an exciting threshold as remote-sensing of exo-atmospheres has now become possible, allowing us to study the thermodynamics and chemistry of planets orbiting stars other than our Sun, and to constrain models of planetary formation and evolution. For this, observations are needed from the visible to the mid-IR portion of the electromagnetic spectrum which are challenging to obtain from the ground. I will review the status of the ARIEL space mission, and discuss the early science it would be possible to obtain on a shorter time-scale using stratospheric balloon instrumentation.
———————– YEAR 2017 ———————–
23-05-2017, 11:00 – Room IB09, ARTOV
Intermittent Turbulence in the Heliosheath and Magnetosheath Plasmas
Dr. Wieslaw M. Macek (Space Research Centre, Polish Academy of Sciences, Warsaw, Poland; Cardinal Stefan Wyszyński University, Warsaw, Poland)
Abstract: Turbulence is complex behavior that is ubiquitous in space, including the environments of the heliosphere and the magnetosphere. Our previous studies on solar wind turbulence, including the heliosheath , and even at the heliospheric boundaries , also beyond the ecliptic plane , have shown that turbulence is intermittent in the entire heliosphere. As is known turbulence in space plasmas could often exhibit a substantial deviation from the normal distribution. Therefore, we also analyze the fluctuations of plasma and magnetic field parameters in the magnetosheath at the Earth’s bow shock. In particular, based on THEMIS observations, we have suggested that turbulence behind the quasi-perpendicular shock is more intermittent with larger kurtosis then that behind the quasi-parallel shocks . Following this study we would like to present detailed analysis of the level of intermittency in the magnetosheath depending on various characteristics of plasma behind the bow shock and near the magnetopause. In particular, we have verified that at higher Alfvénic Mach numbers fluctuations are often more intermittent than at the lower numbers. However, the level of intermittency for the outgoing waves seems to be similar as for the incoming waves. We hope that the difference in characteristic behavior of these fluctuations in various regions of space plasmas can help to detect some complex structures in space missions in the near future.
17-05-2017, 11:00 – Room IB09, ARTOV
The Athena project and its science objectives
Dr. Matteo Guainazzi (European Space Research and Technology Centre, Noordwijk, The Netherlands)
Abstract: In this talk I will present the scientific objectives and design status of Athena – the Advanced Telescope for High-ENergy Astrophysics. Athena was selected in June 2014 as the second L-class mission in ESA’s Cosmic Vision 2015-25 plan, with a launch foreseen in 2028. It is an X-ray observatory designed to address the two questions of Cosmic Vision science theme ‘The Hot and Energetic Universe’: a) How does ordinary matter assemble into the large-scale structures we see today? and; b) How do black holes grow and shape the Universe? It will achieve these goals by studying a wide range of astrophysical phenomena: the formation and evolution of groups and clusters of galaxies; the chemical evolution of hot baryons; feedback effects of active
galactic nuclei; missing baryons thought to populate the intergalactic medium; the formation and early growth of black holes; and the accretion by super-massive black holes through cosmic time, among others. These goals will be achieved through an unprecedented combination of an X-ray telescope with a focal length of 12 m and an effective area of ~2 square meters at 1 keV, and two instruments: an X-ray Integral Field Unit (X-IFU) for spatially-resolved, high spectral resolution (~2.5 eV) imaging spectroscopy over a ~5’x5′ field-of-view, and a Wide Field Imager (WFI) for high count rate, moderate resolution spectroscopy over a large field of view (~40’x40′). The mission is currently in the study phase (“Phase A”) aiming at the scientifically optimal
design. Upon completion, Athena will be proposed for ‘adoption’ around 2019.
25-01-2017, ore 11:00, Aula IB09 ARTOV
Gravity: Where Do We Stand? (Springer, 2016) Presentazione del libro
Roberto Peron (INAF-IAPS)
Abstract: È recentemente uscito per i tipi Springer il libro “Gravity: Where Do We Stand?” (Peron, Colpi, Gorini, Moschella, Ed.). Questo libro ha avuto origine dall’organizzazione della Scuola SIGRAV 2009, dal titolo omonimo, tenutasi a Villa Olmo (Como), estendendo e integrando successivamente gli argomenti trattati. Il tema è l’attuale stato delle conoscenze del fenomeno “gravitazione”, nelle sue varie sfaccettature e su di un ampio intervallo di scale. Ogni capitolo del libro è stato concepito come gradino di una progressione che parte dalla scala di laboratorio, per allargarsi poi a fenomenologie sempre più vaste, dallo spazio circumterrestre al sistema solare a sistemi astrofisici. Ampio spazio è stato dato a questioni di carattere fondazionale, avendo al contempo sempre cura nel sottolineare lo stretto legame fra formulazioni teoriche e verifiche sperimentali. Una parte consistente è stata quindi dedicata ai molti problemi aperti in astrofisica e cosmologia, che chiamano costantemente in causa la gravitazione come motore di molti dei fenomeni osservati.
Il libro verrà presentato da uno dei curatori, ed è prevista la presenza di alcuni degli autori dei capitoli.
20-01- 2017, ore 15:00, Aula IB09 ARTOV
Five years of RadioAstron: pushing the angular resolution limit with Space-VLBI
Gabriele Bruni (Max Planck Institute for Radio Astronomy)
Abstract: During the five years after its launch, the Space-VLBI antenna RadioAstron has broken the records of the highest angular resolution obtained in astronomy, and used its resolutive power to probe brightness temperatures in AGN that exceeds the inverse Compton catastrophe limit. Three key science projects are devoted to the study of AGN physics, from jet launching/collimation to magnetic fields structure, taking advantage of the great detail offered by RadioAstron together with a global supporting ground array of radiotelescopes. I will review the main results of the three KSPs, and the technical challenges that have been overcome in data correlation and processing during these years.
———————– YEAR 2016 ———————–
30-11-2016, ore 11:00, Aula IB09 ARTOV
Francesca Zambon (INAF-IAPS)
Mercury after MESSENGER: preliminary analysis in support to BepiColombo mission
Abstract: The planet Mercury has been explored by two space missions so far. Because of its harsh thermal environment, close exploration of Mercury is challenging. The NASA Mariner 10 spacecraft was the first one to acquire remote sensing data of this planet, back in 1974. Mariner 10 covered 45% of the surface during three Hermean flybys. In recent times, the NASA MESSENGER mission globally mapped the planet and contributed in understanding several unsolved issues on Mercury’s origin, its surface structure, and the nature of its magnetic field, exosphere, and magnetosphere. Nevertheless, after MESSENGER, the surface composition is still debated, and the correlation between morphology and compositional heterogeneity is far from being fully understood.
The Mercury Dual Imaging System (MDIS) onboard MESSENGER achieved global coverage of Mercury’s surface with varying spatial resolution. The surface of Mercury shows differences in composition associated to variations in the spectral slope. By analyzing the spectral slope, relative reflectance, and morphology, three major terrain units have been identified: smooth plains, intermediate terrain, and low-reflectance material.
The mapping process permits integration of different geological surface information, which is required to better understand the planet crust formation and evolution. Our work focuses on the search for a possible connection between the different morpho-stratigraphic units and compositional units. Merging data from different instruments provides additional information about lithological composition, which is key to the achievement of a geochemical map.
The ESA BepiColombo mission, due to be launched in 2018, has an innovative, highly integrated remote sensing package: Spectrometers and Imagers for MPO BepiColombo Integrated Observatory SYStem (SIMBIO-SYS). The VIHI channel of SIMBIO-SYS will enable acquisition of hyperspectral data with enhanced spatial resolution and in a larger wavelength range compared to similar instrumentation flown onboard MESSENGER, meant to improve our knowledge of Mercury’s surface from a geological and compositional standpoint. In addition to this, the Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) and the Mercury Imaging X-ray Spectrometer (MIXS) onboard BepiColombo are also expected to obtain global mapping of the surface. These data may be combined to those returned by SIMBIO-SYS to ultimately achieve a complete geochemical map of Mercury.
10-11-2016, ore 11:00, aula IB09, ARTOV
Vito Francesco Polcaro (INAF-IAPS)
I “Campanari”: un calendario di pietra della Prima Età del Bronzo nella Sicilia Occidentale
Abstract: In provincia di Palermo, all’interno dei confini comunali delle cittadine di San Cipirello e Monreale, ci sono due grandi rocce con fori indubbiamente artificiali, entrambe chiamato localmente “Campanaru” (cioè “campanile”) e poste a meno di otto chilometri l’una dall’altra. Entrambi i fori sono orientati astronomicamente con estrema precisione: la prima roccia, situata sul Monte Arcivocalotto, ha l’asse del suo foro allineato con il sorgere del Sole al solstizio d’inverno, mentre l’altra, situata sulla collina di Cozzo Perciata, punta esattamente al sorgere del Sole del solstizio d’estate. Per quest’ultima esisteva ancora fino a poco tempo fa la tradizione che metteva in relazione il sorgere del Sole nel foro con l’inizio dei lavori di mietitura. Vicino ad entrambi questi megaliti, è archeologicamente ben attestata la presenza di un insediamento datato all’Eneolitico/Prima Età del Bronzo. Gli assi dei fori in entrambe le rocce puntano, da direzioni opposte, a Pizzo Pietralunga, una eccezionale struttura geologica isolata, alla cui base è situato un altro sito dell’Eneolitico/Prima Età del Bronzo, probabilmente di carattere cultuale e / o di scambio delle popolazioni locali. Il fatto che in questa zona ci siano due monumenti coevi e simili (rocce perforate artificialmente) con allineamenti diverse e complementari (solstizio invernale ed estivo) indica che qui, tra l’Eneolitico e la Prima Età del Bronzo, si è sviluppata una civiltà che aveva un calendario solare ed ha sviluppato una tecnologia semplice ma molto efficace per materializzarlo. Altri monumenti megalitici, come il cosiddetto ” Pulpito del Re ” nel vicino parco del Bosco della Ficuzza, risalenti allo stesso periodo e che mostrano ierofanie sorprendenti al sorgere del sole ai solstizi, suggeriscono quale sia stata questa civiltà.
6-10-2016, ore 11:00, Aula IB09, ARTOV
Alberto Adriani (INAF-IAPS)
Juno: Missione a Giove. I primi risultati.
Abstract: La missione Juno a Giove si prefigge di svelare molti dei segreti ancora irrisolti del pianeta più grande del sistema solare. La sonda è equipaggiata con strumenti che permettono lo studio del pianeta in tutti i suoi aspetti dalla magnetosfera che lo circonda fino al suo interno. Verranno illustrate le motivazioni, gli obiettivi scientifici della missione e mostrati i primi dati raccolti durante il primo passaggio in prossimità del pianeta dallo strumento italiano JIRAM, Jovian InfraRed Auroral Mapper.
8-04-2016, 11.00, Aula IB09, ARTOV
Dr.ssa Kazi Rygl (IRA – INAF)
ALMA Cycle 4 Capabilities
Abstract: The Atacama Large Millimeter/submillimeter Array (ALMA) is a complete imaging and spectroscopic instrument operating at frequencies from 84GHz to 950GHz (3mm – 0.3mm). Located on Chajnantor plain of the Chilean Andes, ALMA is the most powerful millimeter/submillimeter interferometer on Earth consisting of two arrays which are sensitive to different angular scales to provide scientists with the best possible sky brightness representation of their targets. I will present the ALMA capabilities offered for the Cycle 4 proposal call, give some examples of science with ALMA cycle 4 observations, and show a brief overview of the Cycle 4 Observing Tool.
08-03-2016, 14:30, Aula IB09, ARTOV
Prof. Yukihiro Takahashi (SMC – Hokkaido University)
Lightning and cloud observations in Venus and Jupiter with spacecraft and ground-telescope
Abstract: Lightning process is an excellent tool to explore the planetary atmosphere through the knowledge of the relationship between the atmospheric dynamics and electrical charge.
It has been suggested for a decade that thunderstorms in Jupiter’s atmosphere take important roles not only in the investigation of meteorology, which determines the large scale structures such as belt/zone and big ovals, but also in probing the water abundance of the deep atmosphere, which is crucial to constrain the behavior of volatiles in early solar system.
Here we suggest making observation of thunderstorm activity using lightning flash detection and cloud imagery with JUICE spacecraft and ground-based telescopes. Observing H Balmer Alpha line (656.3nm), we could estimate the activities of thunderstorms quantitatively, which enables us to investigate the mechanism of large structure formation.
As for the lightning activity in Venus, even though extensive investigations using data obtained with spacecraft and ground-based telescopes have been carried out, we don’t reach consensus on the existence of lightning in that planet. Indeed there exist some strong indications of electrical discharge both in optical and radio wave measurements. But these “evidences” are sometimes not accepted in the majority of researcher community. For example, it is reported that the magnetometer on board Venus Express recorded whistler mode waves whose source could be lightning discharge occurring well below the spacecraft.
LAC is the first sensor designed for the lightning detection in Venus. In order to identify the optical flash caused by electrical discharge in the atmosphere of Venus, at least, with an optical intensity of 1/10 of the average lightning in the Earth, we built a high-speed optical detector, LAC (Lightning and Airglow Camera), on board Akatsuki spacecraft. Unique performance of LAC compared to other equipments is the high-speed sampling rate at 32 us interval for all 32 pixels of APD matrix, enabling us to distinguish the optical lightning flash from other pulsing noises. We selected OI 777 nm line, the most expected emissions in CO2 atmosphere based on the laboratory experiment. After orbit insertion of Akatsuki, the elongated orbit allows umbra for ~30 min to observe the lightning flash in the night side of Venus every ~10 days after April 2016. Here we would report the instrumental status of LAC and the testing result together with future plans and strategy of LAC operation.
———————– YEAR 2015 ———————–
09-12-2015, 11:00, Aula IB09, ARTOV
Dr.ssa Nazma Islam Syeda (Raman Research Institute – Indian Institute of Science)
Long term observations of X-ray binaries with All Sky Monitors: New results
Abstract: I will describe some new studies carried out using long term light curves of X-ray binaries with various X-ray all sky monitors. 16 years of RXTE-ASM light-curves are utilised to construct multiple snapshots of X-ray Luminosity Functions (XLF) of the X-ray binaries in the Milky Way and study the effect of variability of X-ray binaries on them. Using orbital phase resolved spectroscopic measurements of the bright High Mass X-ray binary GX 301-2 with an unprecedented orbital coverage with MAXI, we examined various models about the mode of accretion on to the neutron star. Presence of an eclipse in a X-ray binary can be useful in determining orbital parameters like inclination and estimating the orbital evolution by eclipse timing method. The orbital period evolution of the eclipsing X-ray binary 4U 1700-37 was measured using long term light-curves obtained with the all sky monitors RXTE–ASM, Swift–BAT and MAXI–GSC. We have also used the mid-eclipse times and the eclipse duration measurements obtained from 10 years long X-ray light curve obtained with Swift–BAT to separately put constraints on the eccentricity of the binary system and attempted to measure any apsidal motion.
The orbital intensity profile of another X-ray binary IGR J16393-4643 created with Swift-BAT shows it to have a short eclipse, which is used to constrain the inclination of this system. With 5 years of MAXI-GSC data, we have for the first time measured long term averaged spectra of X-ray binaries and have constructed composite X-ray binary spectrum of the Milky Way. The long term averaged composite spectrum will be an useful input to realistically estimate the contribution of X-ray heating at the epoch of re-ionization. I will also describe the various payloads onboard the recently launched Indian multi-wavelength astronomy mission ASTROSAT.
30-10-2015, 11:00, Aula IB09, ARTOV
Dr.ssa Valeria Mangano (IAPS – Roma)
THEMIS Na exosphere observations of Mercury and their correlation with in-situ magnetic field measurements by MESSENGER
Abstract: The Na exosphere of Mercury is being studied since its discovery in mid ’80s from Earth-based telescopes, and it has revealed a high dynamicity and variability. Although the processes and inter-relations characterizing the Hermean exosphere dynamics are still not thoroughly understood, the existence of a connection among the planet’s surface, exosphere, intrinsic magnetic field and the Interplanetary Magnetic Field (IMF) that drives Solar Wind ions into Mercury’s magnetosphere via magnetic reconnection, is undoubtful.
We analyzed an extended dataset of images of the exospheric Na emission, corresponding to the period from 2009 to 2013, obtained by the THEMIS ground-based telescope, in order to perform a comprehensive statistical study of the recurrent patterns and their relationship with the IMF variability. For this purpose, we take advantage of a subset (years 2011-2013) of contemporary in-situ measurements of the IMF obtained by the MAG instrument onboard the MESSENGER spacecraft.
Data seem to confirm that the mid-high latitude double peak configuration is the most common Na emission pattern, supporting the view that the solar wind ion precipitation through the polar cusps has an important role in the generation of the observed Na exospheric emission. Moreover, the lack of a statistically significant North-South asymmetry seems to disfavour the idea of an asymmetric and/or shifted magnetic dipole.
In addition, comparison with the IMF data indicates that the contribution of the IMF Bx component to the magnetic reconnection is generally weak while negative IMF Bz values are usually connected with double peaks emission and positive IMF Bz valules are more frequently associated to single peaked equatorial Na emission.
28-10-2015, 11:00, Aula IB09, ARTOV
Dr. Gianni Bernardi (SKA Africa & Rhodes University)
The South African pathway to the Square Kilometre Array)
Abstract: The Square Kilometre Array (SKA) is a radio telescope array that promises to revolutionize our knowledge of the Universe. It is currently planned and designed by a consortium of countries (including Italy) and will be built on South Africa (mid-high frequency component) and Australia (low frequency component). In South Africa the SKA will incorporate the MeerKAT pathfinder, a 64 antenna radio interferometer that will operate in the 0.5-1.6 GHz regime. MeerKAT is preceded by the engineering testbed 7-antenna Karoo Array Telescope (KAT-7) that has been successfully commissioned and has been operated in “science mode” since a few years. I will review the current status of radio astronomy development in South Africa, paving the way to the SKA and outlining opportunities for the community.
06-10- 2015, 11:30, Aula IB09, ARTOV
Dr. Robert Carlson (Jet Propulsion Laboratory California Institute of Technology Pasadena, USA)
Jupiter’s Great Red Spot: Possible chromophores from photolysis of ammonia in the presence of acetylene
Abstract: The high altitude of Jupiter’s Great Red Spot (GRS) may enhance the upward flux of ammonia (NH3) gas into the high troposphere, where NH3 molecules can be photodissociated and initiate a chain of chemical reactions with downwelling acetylene molecules (C2H2). These reactions, experimentally studied earlier by Ferris and Ishikawa (Ferris and Ishikawa, 1987; Ferris and Ishikawa, 1988), produce chromophores that absorb in the visible and ultraviolet. In this work we photolyzed mixtures of NH3 and C2H2 with methane (CH4) using ultraviolet radiation with a wavelength of 214 nm and measured the spectral transmission of the precipitated films in the visible region (400-700nm). From these transmission data we derived the imaginary indices of refraction.
Assuming that ammonia grains at the top of the GRS clouds are coated with this material we performed layered sphere and radiative calculations to predict GRS reflection spectra. Comparison of these results with reflectance spectra and true-color images of the GRS shows that the unknown GRS chromophore is spectrally consistent with the coupled NH3-C2H2 photochemical products produced in our laboratory experiments. These laboratory-produced chromophores consist of aliphatic imines, amines, and nitriles, isonitriles, and ketenimines.
07-09-2015, 11.00, Aula IB09, ARTOV
Prof. Gary Zank (University of Alabama at Huntsville, USA)
Diffusive Shock Acceleration and Reconnection Processes
Abstract: An emerging paradigm for the dissipation of magnetic turbulence is via localized small-scale reconnection processes, essentially between quasi-2D interacting magnetic islands. Charged particles trapped in merging magnetic islands can be accelerated by the electric field generated by magnetic island merging and the contraction of magnetic islands. We have derived a gyrophase-averaged transport equation for particles experiencing pitch-angle scattering and energization in a super-Alfvenic flowing plasma experiencing multiple small-scale reconnection events. A simpler advection-diffusion transport equation for a nearly isotropic particle distribution has been derived from the gyrophase-averaged transport description. The dominant charged particle energization processes are 1) the electric field induced by quasi-2D magnetic island merging, and 2) magnetic island contraction. The magnetic island topology ensures that charged particles are trapped in regions where they experience repeated interactions with the induced electric field or contracting magnetic islands. Shock waves naturally generate vertical turbulence downstream of shocks. This introduces an additional possibility or mechanism to accelerate particles distinct from classical diffusive shock acceleration (DSA). We present a new mechanism that combines DSA with particle acceleration by reconnection-related processes. We discuss the nature of the spectra and the evolution of the energetic particle intensities with distance from the shock wave. We relate our theoretical models to observations made of energetic particles at the heliospheric termination shock that cannot be explained on the basis of classical DSA.
24-06-2015, 16:00, Aula IB09, ARTOV
Dr. Andrea Tramacere (ISDC – Data Center for Astrophysics, Versoix – Ginevra)
Application of topological clustering algorithms in automatic galaxy shape classification
Abstract: We present a method based on topological clustering algorithms aimed to automatic galaxy shape classification, based on a novel combination of clustering algorithms (DBSCAN and DENCLUE). The method does not require any external tool to extract the galaxy from the CCD image.
In a first stage, we use the DBSCAN algorithm to extract the cluster of pixels belonging to the galaxy. In a second stage, we apply the DENCLUE algorithm to this cluster of pixels, obtaining a partition the initial galaxy image in sub-clusters generated from the localization of local maxima, by a kernel density estimation. Typically, elliptical galaxies are characterized by a single sub-cluster, whilst spiral ones present several sub-clusters related to different segments of arms. The arms segments are then merged, and fitted by a log-spiral analytical function, and the resulting parameters provide a sub-set of the features. Further topological and statistical features are extracted from the distribution of the sub-clusters, and from the computation of geometrical invariant moments of the pixels belonging to the contours of the galaxy, and to the sub-clusters. Finally these features are used with different classifiers, such as Random Forest.
We present results for a sample of galaxies from SDSS Stripe 82 data set, and we compare our classification results to GalaxyZoo2 ones.
11-06-2015, 11:00, Aula Comitato, ARTOV
Dr. Simone Marchi (Institute for the Science of Exploration Targets Colorado)
Widespread mixing and burial of Earth’s Hadean crust by asteroid impacts
Abstract: In this talk I will present a new bombardment model of the Hadean Earth (4.0-4.5 billion years ago) that has been calibrated using existing lunar data and terrestrial highly siderophile elements. We find that the surface of the Hadean Earth was widely reprocessed by impacts through mixing and burial by impact-generated melt. This model may explain the absence of early terrestrial rocks. Furthermore, we will discuss an intriguing correlation between the age distribution of Hadean zircons and the impact flux, possibly indicating impacts played an important role in Hadean zircon formation. Finally, by tracking the magnitude and timing of early collisions, we find that existing oceans would have repeatedly boiled away into steam atmospheres as a result of large collisions as late as about 4 billion years ago.
03-06-2015, 11.00, Aula IB09, ARTOV
Prof. Toru Tanimori (Department of Physics, Kyoto University, Kyoto Japan)
Development of Electron Tracking Compton Camera (ETCC) for a Survey of Deep Universe by MeV gamma-rays
Abstract: ETCC with a gas Time Projection Chamber (TPC) and pixel GSO scintillators, by measuring electron tracks, provides both a strong background rejection by dE/dx of the track and clear imaging by adding the arc direction of incident gammas (SPD: Scatter Plane Deviation) with the ARM (angular Resolution Measure) direction measured in standard Compton Camera (CC). In 2006 its background rejection was revealed by SMILE-I balloon experiment with 10 cm-cubic ETCC using the dE/dx of tracks. In 2013, 30 cm-cube-ETCC has been developed to catch gammas from Crab in next SMILE-II balloon with >5 sigma detection for 4 hrs. Now its sensitivity has been improved to 10 sigma by attaining the angular resolution of the track (SPD angle) to that determined by multiple scattering of the gas. Thus, we show the ability of ETCC to give a better significance by a factor of 10 than that of standard CCs having a same detection area by electron tracking. Based on this technology, SMILE-II with 3 atm CF4 gas is expected to provide a 5 times better sensitivity than COMPTEL for one month balloon flight around the polar region, and 4 modules of 50 cm-cube ETCCs would exceed over 10^-12 erg/cm^2s^1 (1 mCrab) at 10^6 s in satellite.
To verify its performance in space, SMILE-II was irradiated by intense gammas and neutron using 140 MeV proton beam, and successfully measured both clear image of a weak RI without the efficiency deterioration under 10 times stronger radiation than that in space.
Here we summarize the performance of the ETCC and new astrophysics opened in near future by high-sensitivity observation of MeV gamma-rays.
14-05-2015, 11:00, Aula IB09, ARTOV
Dr. Yasuo Fukui (Department of Physics Nagoya University)
How to form Spitzer bubbles: Wind bubbles or collision-created cavities
Abstract: It is generally believed that the Spitzer bubbles are formed by winds by O stars. In this scenario, the mechanism of the formation of the central O star remains unexplained. Recent CO observations of RCW120, one of the most typical Spitzer bubbles, show that RCW120 may have been formed by collision between a small cloud and a large cloud (Torii et al. 2015 ApJ in press, http://ads.nao.ac.jp/abs/2015arXiv150300070T). In this scenario, a cavity is created in the large cloud by the collision and the central O star formed by the collisional triggering illuminates the inside of the cavity, which is observable as a bubble-like infrared nebula. I will discuss the pros and cons of the cloud-cloud collision scenario and the wind bubble scenario, and the implications on star formation.
06-05-2015, 11:00, Aula IB09, ARTOV
Dr. Riccardo Claudi (INAF – Osservatorio Astronomico Padova)
Pianeti Extrasolari, HARPS-N@TNG e GAPS
Abstract: GAPS (Global Architecture for Planetary Systems) è una collaborazione che raccog,lie in se tutta o la maggior parte della comunità esoplanetaria italiana. E’ una collaborazionee aperta a nuove adesioni ed è stata sollecitata dall’INAF nel 2011 con una “open call” quando l’ente ha deciso di dedicare molte risorse all’integrazione di HARPS – N al Telescopio Nazionale Galileo. Un adeguato uso del migliore strumento al mondo per la misura di velocità radiali ha come contropartita uno sforzo non indifferente per coordinare e gestire la comunità che potenzialmene lo può usare.
La storia comincia a padova nel 2011 e poi continua a Roma nel 2012 dove questo gruppo si è costituito. GAPS comincia ufficialmente le sue osservazioni in agosto 2012, da allora ha avuto un totale di 1764 ore assegnate (1456 effettivamente osservate), distribuite nei vari sotto progetti che lo costituiscono. Lo scopo di GAPS è molteplice ed è suddiviso in diversi blocchi che permettono di capire l’architettura dei sistemi planetari: 1) studiare la frequenza di pianeti di piccola massa in funzione della massa e della metallicità delle stelle ospite e della densità dell’ambiente stellare; 2) caratterizzare i pianeti noti; 3) analizzare l’attività delle stelle ospiti ed il suo effetto sulla derivazione dei parametri planetari; 4) derivare misurazioni accurate della massa planetaria per mezzo dello studio asterosismologico delle stelle ospiti.
Dal 2012 ad oggi sono stati ottenuti molti risultati che saranno oggetto di questo seminario, non ultimo quello di aver coagulato intorno al miglior cacciatore di pianeti un’intera comunità.
29-04-2015, 11.00, Aula IB09, ARTOV
Tanmoy Chattopadhyay (Physical Research Laboratory of Ahmedabad – India)
X-ray Polarimetry Programs in Physical Research Laboratory (PRL), India
Abstract: Hard X-ray polarimetry is supposed to provide better understanding of celestial X-ray sources. Compton polarimeters when coupled with hard X-ray optics can provide sensitive polarisation measurements in hard X-rays with a broad energy band. In this regard, we are developing a focal plane hard X-ray Compton polarimeter consisting of a plastic scintillator as active scatterer surrounded by a cylindrical array of CsI scintillators read by Si Photomultipliers. Here I briefly describe the experimental results obtained from the final polarimetric configuration.
Apart from this, CdZnTe Imager (CZTI) onboard Astrosat, can also work as a potential Compton polarimeter in 100 – 300 kev range due to its multi-pixel detection capability and significant Compton efficiency in this energy range. We have experimentally verified the polarization measurement capability of CZTI modules. Astrosat is going to be launched in 2015 end and therefore gives unique opportunity to measure polarization of few bright hard X-ray sources e.g. Crab nebula and CygX1. Prospects of hard X-ray polarimetry with CZTI, will also be discussed here briefly.
17-04-2015, 11.00, Aula Convegni, ARTOV
Dr. Claudio Maccone (International Academy of Astronautics)
“SETI and ASTROBIOLOGY: current status”
Abstract: SETI and ASTROBIOLOGY have long been regarded as two separate research fields. The growing number of discovered exoplanets of various sizes and characteristics, however, forces us to envisage some sort of CLASSIFICATION of exoplanets based on the question: *where does a newly-discovered exoplanet stand ON ITS WAY TO DEVELOP LIFE ?*
This author has tried to answer this question in a mathematical fashion by virtue of his “Evo-SETI” (standing for “Evolution and SETI”) mathematical model. The results were two papers published in the International Journal of Astrobiology, the first of which turned out to be the second most-widely read paper in the International Journal of Astrobiology in the year 2013. In this seminar the Evo-SETI mathematical model is described in mathematical detail for the benefit of researchers.
25-03-2015, 11.00, Aula IB09, ARTOV
Prof. Jean-Claude Gerard (Université de Liège, Belgium)
Jupiter’s aurora, ultraviolet, visible and infrared views: what can we learn?
Abstract: Precipitation of energetic electrons from Jupiter’s magnetosphere into the atmosphere is a powerful process which generates a photon flux of a few 1011 to 1012 Watts. Unlike the Earth’s or Saturn’s case, aurora on Jupiter is not located near the boundary between open and closed magnetic field line. It is powered by the planet’s fast rotation which creates a global current system and accelerates electrons into the atmosphere where their collisions with H2 produce the spectacular aurora. Most of the observations on the morphology and its relation with the solar wind have been collected with the ultraviolet cameras on board the Hubble Space Telescope. These observations have also shown that changes in Io’s volcanic activity also controls to some extent the size if the aurora. Observations of the H3+ emission in the infrared have been obtained with ground-based telescopes and show similarities with their UV counterparts. Some differences are also seen, probably stemming from the sensitivity of the IR emission to the local gas temperature. The main morphological features of the Jovian aurora will be presented and the unique case so far when images were simultaneously collected in the UV and IR will be analysed. Possible reasons for differences will be discussed. We shall also describe recent work using UV spectral imaging that made it possible to remotely map the energy of the precipitated electrons. Perspectives to combine future observations collected with UVS and JIRAM on board the Juno orbiter will be discussed.
12-03-2015, 11.00, Aula IB09, ARTOV
Dr.ssa Christina Plainaki (INAF – IAPS)
A global model for Ganymede’s exosphere in view of the JUICE mission
Abstract: The interactions between Jupiter’s magnetospheric plasma and Ganymede’s icy surface are responsible for the generation of the moon’s neutral environment. Such interactions are strongly constrained by the moon’s intrinsic magnetic field determining the pattern of the ion precipitation to the icy surface. In this paper, the water and oxygen exospheres of Jupiter’s moon Ganymede are simulated through the application of a 3D Monte Carlo modeling technique that takes into consideration the combined effect on the exosphere generation of the main surface release processes (i.e. sputtering, sublimation and radiolysis) and the precipitation of the magnetospheric ions to the moon’s surface. We find that plasma precipitation occurs in a region related to the open-closed magnetic field lines (OCFB) boundary and its extent depends on the assumption used to mimic the plasma mirroring in Jupiter’s magnetosphere. In the full mirroring assumption, the primary surface sputtering mechanism at the whole polar cap of Ganymede can alone explain the observed higher albedo of this region; in the non- mirroring assumption the polar cap brightness above the OCFB ring can be explained with the action of secondary sputtering due to ionized exospheric particles re-impacting the surface. At small altitudes above the moon’s subsolar point the main contribution to the neutral environment comes from sublimated water; the spatial distribution of the directly sputtered-water molecules exhibits a close correspondence with the plasma precipitation region and extends at high altitudes, being, therefore, well differentiated from the sublimated water. The oxygen exosphere comprises two different populations: a thermal one (extending to some 100s of km above the surface) and a more energetic one consisting of more energetic oxygen molecules sputtered directly from the surface after water-dissociation by ions has taken place.
The availability to the science community of such an exospheric model could be of help during the planning of the future JUICE mission observations. The interdisciplinary study of endogenic/exogenic surface release processes– with their potential implication on the nature of the moon’s inner ocean – have as mandatory prerequisite an accurate characterization of Ganymede’s exospheric background.
20-01-2015, 11:00, Aula Convegni, ARTOV
Prof. C. T. Russell (University of California, Los Angeles)
The Dawn Discovery Mission: A Voyage in Space and Time
Abstract: Giuseppe Piazzi discovered Ceres 214 years ago. Almost exactly 2 centuries later NASA selected the Dawn mission to visit Ceres and map it completely. On the way to Ceres it studied Vesta, discovered in 1807 two centuries before Dawn’s launch. In this talk we present a short summary of the Dawn objectives, the spacecraft, the observations made at Vesta, and the planned observations at Ceres.