posters - Osservatorio di Arcetri

POSTERS
Virginia Botte
Dipartimento di Astronomia – Università di Bologna
OI 8446 in NLS1 galaxies
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Alessandra Beifiori
Dipartimento di Astronomia – Università di Padova
A. Beifiori, E. M. Corsini, E. Dalla Bontà, A. Pizzella, M. Sarzi, F. Bertola
Upper limits on the mass of supermassive black holes from HST/STIS archival data
The growth of supermassive black holes (SBHs) appears to be closely linked with the formation
of spheroids. From the observational point of view there is a pressing need to acquire better
statistics on SMH masses since the existing samples are preferentially weighted toward earlytype galaxies with very massive SBHs. With this motivation we started a project aimed at
measuring upper limits of the mass of the SBHs that can be present in the centers of all the
nearby galaxies (D<100 Mpc) for which STIS/G750M spectra are available in the HST archive.
These upper limits will be derived from the modeling of the central emission-line widths
([NII]6548,6583AA , Halpha, and [SII]6716,6730AA) observed over an aperture of ~0.1'' (R<50
pc). In this poster we present our preliminary results about a subsample of 50 bulges
Giacomo Briani
Dipartimento di Astronomia – Università di Firenze
G. Briani, G. Pupillo, S. Aiello, E. Pace, S. Shore, A. Passaro
Studio di micrometeoroidi nell’atmosfera terrestre
E’ stato suggerito che molecole organiche complesse, in grado di catalizzare la sintesi di
composti biochimici prebiotici, siano state depositate sulla Terra da corpi extraterrestri nell’arco
dei primi 800 milioni di anni dopo la formazione della Terra. Questo scenario è basato sulla
grande abbondanza di composti organici trovati in condriti carboniose. Particelle di polvere
interplanetaria, micrometeoroidi (MM) e meteoroidi che sopravvivono, almeno parzialmente,
all’ingresso in atmosfera, sono i più plausibili vettori per il trasporto di materiale organico intatto
sulla Terra. I MM, in particolare, sono interessanti perché rappresentano la maggior parte
dell’attuale flusso di materia extraterrestre verso la Terra e probabilmente sono stati la
principale fonte di carbonio organico anche per la Terra primordiale. Inoltre i MM possono darci
informazioni sui corpi minori del Sistema Solare (probabilmente i loro corpi progenitori sono
asteroidi o comete) o direttamente sull'origine del Sistema Solare (alcuni dei MM potrebbero
essersi formati proprio durante la condensazione della nebulosa pre-solare).
Un punto critico per capire il ruolo dei MM è il riscaldamento che sperimentano durante il volo
atmosferico, quando raggiungono alti valori di temperatura (ai quali le specie organiche
possono sublimare o decomporsi) e perdono parte della loro massa. Noi abbiamo sviluppato un
nuovo modello generale per il passaggio di MM attraverso l'atmosfera, in cui si considerano
molti processi fisici diversi (variazioni di velocità, temperatura, dimensioni?) ma, allo stesso
tempo, complementari. Con il nostro modello vogliamo affrontare il problema da un punto di
vista globale e, considerando quelli che possono essere i processi fisici più importanti per
stabilire il destino di un MM che entra nell'atmosfera, evidenziare come un dato processo può
essere il risultato di meccanismi fisici diversi. Il modello include le equazioni che descrivono
l'evoluzione di velocità, temperatura, massa e dimensioni dei MM ed anche il calcolo della
magnitudine delle micrometeore associate. Recentemente è stato introdotto il calcolo del profilo
della temperatura interna, per valutare l’eventuale differenza di temperatura tra la superficie ed
il centro di un MM e l'effetto di trasformazioni (ad esempio la deidratazione) dei minerali che
costituiscono un MM.
Nella presentazione sarà discusso il problema generale dell'interazione micrometeoroidiatmosfera, con particolare attenzione a quali possano essere i più importanti processi fisici e a
come possano essere modellizzati. Saranno presentati i risultati del nostro modello, insieme ai
possibili miglioramenti futuri.
Innocenza Busà
INAF - Osservatorio Astrofisico di Catania
I. Busà, G. Catanzaro
The outer atmosphere of the RS CVn variable HR 7428
We infer informations on the physical properties of the outer atmosphere of the RS CVn binary
system HR7428 by means of semi-empirical atmospheric modeling of the K2 cool component of
the system. The work, based on the spectroscopic Halpha and Mg II diagnostic, aims to
understand the nature of the H alpha broad extra-absorption observed by many authors.
Daniela Cardini
INAF / IASF
Rotational evolution in late type main-sequence stars
We have carried out a study of the rotation-age relationship in a large sample of late type mainsequence stars. The study is based on rotation period data of single stars taken from the
literature. From the analysis of the data relative to open clusters and field stars we find that
rotational periods decrease linearly with increasing mass in stars of same age. This linear
sequence evolves as a power of age (t^0.45). This result is compatible with that obtained by
Skumanich (1972) for 1 solar mass stars, and extends its applicability to a broader range of
masses.
Andrea Cardullo
Dipartimento di Astronomia - Università di Padova
A. Cardullo, E.M. Corsini, A. Pizzella, F. Bertola
Ultraviolet variability in the nucleus of elliptical galaxy NGC 4278
We searched the Hubble Space Telescope Science Archive to investigate UV variability in the
nuclei of elliptical galaxies. We looked for galaxies which were observed more than once with
ACS and/or WFPC2 imagers.
We detected the presence of a strongly variable point-like source in the nucleus of NGC 4278.
This UV flare was previously unknown and we give an estimation of the mass of the central
supermassive black hole.
A. Cardullo, A. Pizzella, E.M. Corsini, F. Bertola
Kinematics and dynamics of low surface-brightness galaxies
Major and minor axis stellar and ionized-gas kinematics of a sample of bulge dominated low
surface-brightness galaxies is presented.
The stellar kinematics, together with broad-band imaging, is used to construct detailed mass
models aimed at deriving the central density profile of the dark matter component.
Elisabetta Cesarini
Dipartimento di Astronomia - Università di Firenze
Thermomechanical characterization of materials for future interferometric GW detectors
In a broad region between few tens of Hz up to 1 kHz, the sensitivity of interferometric
gravitational wave antennae is dominated by thermal excitation of test masses and suspensions
vibrational modes. Thermal noise can be reduced by using suitable materials, with low
mechanical losses, or by cooling masses and suspensions. In both cases, a thorough
experimental characterization of thermomechanical properties of materials, such as thermal
conductivity and dissipation, has to be combined with a theoretical understanding of the
observed behavior, in order to design a next generation detector. In this poster, the
experimental activity of Firenze-Urbino group, in the layout of Virgo collaboration, will be
presented; its laboratory is devoted to the experimental study of thermomechanical properties of
materials to be employed in test masses. A facility for measuring the thermal conductivity has
been set up and tested, and measurements on silicate bonded Si samples, in collaboration with
the IGR group in Glasgow, are carried out. A new nodal suspension for measuring the
dissipation factor in bulk substrates has been realized and is now under test; this suspension
will allow a non disruptive determination of coating losses in coated substrates.
Valentina Cracco
Dipartimento di Astronomia – Università di Padova
Morphology and photometry of isolated Seyfert galaxies
An important, unresolved, problem about active galactic nuclei (AGN) is the determination of the
mechanism responsible for nuclear activity. In particular, gas or other material needs to lose
angular momentum to fall into the galaxy nucleus and fuel the supermassive black hole.
Many authors proposed a lot of different solutions: circumnuclear star clusters, bars, disks or
nuclear spirals, interactions between galaxies, and mergers.
Here we present preliminary results about morphological and photometric analysis of a sample
of 35 nearby (z<0.03) and isolated or partially isolated Seyfert galaxies, observed through
broad-band BVR filters at the 1.8 m Vatican Telescope and the 2.2 m ESO-La Silla Telescope.
This work is part of a larger project focused on the study of the possible causes of AGN
triggering.
Valentina D'Orazi
Dipartimento di Astronomia – Università di Firenze
Chemical abundances in Orion Nebula Cluster from Low-Mass Stars
We present the results of a spectroscopic analysis of pre-main sequence low-mass stars
belonging to Orion Nebula Cluster (ONC). Our main goal is the determination of metallicity of
our sample of 7 stars, spanning a mass range from 0.9 M0 to 1.4 M0, by means of the fit of Fe
I observed profiles with MOOG synthetic profiles.
We find a very close to solar metallicity for most stars, consistentenly with previous results
obtained from both B-type main sequence stars (Cunha & Lambert, 1994) and F-G pre-main
sequence stars (Cunha, Smith & Lambert 1998). We also derived Nichel and Titanium
abundances for a sub-sample of 4 and 3 stars, respectively: this is the first determination in
literature and the [Ni/Fe] and [Ti/Fe] values are roughly solar.
Lisa Gambicorti
Dipartimento di Astronomia – Università di Firenze
L. Gambicorti, D. Magrin, M. Munari, E. Pace, I. Pagano, S. Scuderi, B. Shustov.
WSO-UV Field Camera Unit preliminary optical layout
The WSO-UV telescope, a 1.7 m UV-optimized space observatory, will investigate numerous
astrophysical phenomena from planetary science to cosmology.
The Field Camera Unit (FCU), an Italian lead project, is one of the focal plane instruments
aboard. The FCU will have three channels that will cover a wide spectral range going from 115
nm to 700 nm. It will have imaging and spectropolarimetric capabilities. This poster describes
the preliminary optical design of the 3 channels and the expected optical performances.
Silvio Giordano
INAF - Osservatorio Astronomico di Torino
S. Giordano, A. Cora, C.A. Volpicelli and S. Mancuso
MINVIT a Multi INstrumental VIsualization Tool for Solar Physics Data
In recent years a lot of effort has been performed to construct systems for the sharing of
resources within the solar physics community (eg. EGSO and SOLARNET). Several advanced
archives and multi-instrumental analysis systems (e.g SolarSoft) do exist, but there is not
availability of a data visualization tool for simultaneous display of multi instrument/wavelength
solar data. Meanwhile map server technology has received great attention by the IT Researcher
and Geophysical community.
In this paper we discuss an example of possible use of Open Source environment for building
spatially-enabled Internet applications dedicated to the visualization and analysis of Solar
Physics Data set. As we show, MINVIT (Multi INstrumental VIsualization Tool) shall be able to
merge images and information produced by different instruments on board SOHO in a
single/synoptic image available via WEB. Moreover it allows to display the temporal evolution of
data. We also discuss its integration into Grid Framework, focusing on a middleware be able to
query EGSO resources like UOC and SEC in order to include data from several space and
ground-based solar observatories.
Domenico Impiombato
Dipartimento di Fisica e INFN – PERUGIA
D. Impiombato, G. Tosti, Collab. TEAM REM
Osservazioni ottiche e nel vicino infrarosso di un campione di blazar con il telescopio
REM
Il telescopio REM (Rapid Eye Mount), installato a La Silla (Cile) nel giugno del 2003, è un
telescopio di nuova generazione, completamente robotizzato ed è in grado di ospitare
contemporaneamente più strumenti permettendo di eseguire simultaneamente fotometria ottica
ed infrarossa oltre a spettroscopia a bassa risoluzione di transienti (soprattutto di prompt
afterglow dei gamma-ray burst rivelati dal satellite SWIFT). In questo poster illustriamo il
monitoraggio ottico ed infrarosso di campioni blazars che emettono anche nella banda di
emissione gamma e che saranno di supporto alla continuazione della ricerca scientifica con le
missioni di GLAST ed AGILE ; inoltre presentiamo le osservazioni ed un lavoro di analisi dei
dati e dei flares sulle immagini d’archivio delle sorgenti di gennaio 2007.
Simone Marchi
Dipartimento di Astronomia – Università di Padova
C. Barbieri, S. Billotta, P. Bolli, G. Bonanno, A. Di Paola, C. Facchinetti, E. Giro, S. Marchi,
G. Naletto, T. Occhipinti, C. Pernechele, E. Sain, E. Verroi, M. Zaccariotto, P. Zoccarato.
Status of AQUEYE, the fast multichannel photometer for the 182cm telescope at Cima
Ekar
In 2005 we designed a possible focal plane instrument (QuantEYE) for the 100 m OverWhelmingly Large Telescope (OWL) of the European Southern Observatory, as the fastest
photon counting astronomical photometer ever conceived, with an array of 100 parallel
channels, capable to push the time tagging capabilities toward the pico-second region.
Thanks to this extremely high time resolution, and to the enormous photon flux at the output of
OWL, it would be possible for the first time to study second-order statistical functions in the
photon stream from celestial sources. To acquire real experience with such novel type
of astronomical instrumentation, we are now in the process of realizing a small prototype
(AquEYE) for the Asiago 182 cm telescope. AquEYE will have four independent photon
counting channels. All the main building blocks of Aqueye are in the laboratory, in advanced
status of verification and assembly.
This paper will describe the main results obtained so far. As example of scientific programs
we plan to tackle with it, we plan to follow the ingress and egress of extrasolar transiting
planets, in order to determine with the highest accuracy the perturbation of the orbital
elements to detect low mass unseen companions.
Lorenzo Matteini
Dipartimento di Astronomia - Università di Firenze
Evoluzione della anisotropia di temperatura dei protoni nel vento solare da 0.3 a 2.5 UA
Presentiamo uno studio della evoluzione della anisotropia delle funzioni di distribuzione dei
protoni nel vento solare da 0.3 a 2.5 UA. I dati utilizzati provengono delle missioni Helios I, II e
Ulysses e riguardano sia il vento veloce che il vento lento. L'evoluzione della anisotropia di
temperatura evidenzia il ruolo di instabilità di plasma nell'espansione del vento e nella
regolazione della sua dinamica macroscopica. L'anisotropia risultante è in buon accordo con i
vincoli derivanti dalla teoria lineare (Vlasov) e rispecchia gli andamenti trovati in recenti
simulazioni numeriche nelle quali il vento è predetto espandere lungo un cammino di stabilità
marginale della instabilità "fire hose"; i dati Ulysses a grande distanza qui analizzati per la
prima volta confermano questo andamento.
Sergio Messina
INAF - Osservatorio Astrofisico di Catania
The RACE-OC project: Rotation and Activity Evolution in Open Cluster
We present an ongoing project consisting of multiband long-term CCD photometric observations
of open stellar clusters of different age, ranging from about 1 to 500 Myr. Our sample consists of
twelve clusters, seven of which have already been observed at least in one season. From this
project we expect: a) to identify the cluster members, b) to determine the rotation period of the
late-type cluster members; c) to determine their rotational period distribution; and c) to study the
short-term (rotational) and long-term (cyclical) magnetic variability by using photospheric
activity tracers. Once the observations of all clusters will be completed for at least one season,
we plan to better describe and model the evolution of the stellar angular momentum from the
PMS to the TAMS. Moreover, we intend to investigate in a statistically complete stellar sample
the dependence and evolution of magnetic activity on the global stellar parameters in the
framework of the current dynamo theories, thanks to the repeated year-to-year observations.
Maurizio Pancrazzi
Dipartimento di Astronomia – Università di Firenze
The Data Handling Unit for the World Space Observatory
The World Space Observatory (WSO) is a space telescope conceived to observe the universe
in the UV. The instrument payload consists of three spectrographs and one Field Camera Unit
(FCU) composed by three cameras for UV and visible light imaging.FCU instrument
(responsibility of Italian team) will produce a huge quantity of data to be transferred in a short
time to the control ground stations. The XUVLab of the Department of Astronomy of Florence
University is developing the Data Handling Unit for FCU instrument. Since the data volume will
be very huge it cannot be possible to store images on the computer mass storage for a long
time. At the moment the proposed satellite interface is the MIL1553B which represents a
bottleneck dued to its low data rate. In order to avoid very long images transfer time (which
could be a very strong constraint against scientific requirement), we are designing a
communication interface that uses an hybrid architecture which is capable of high-speed and
reliable data transfer.
Linda Podio
INAF-Osservatorio Astrofisico di Arcetri – Firenze
Spectral analysis of stellar jets: from large to small scales
Stellar jets play a key role in the overall star formation process. The ejection of these flows, in
fact, is deeply connected with the accretion process and they can be responsible for the
removal of the excess angular momentum from the disk, thus allowing the material to accrete
from it onto the star.
To confirm this picture and to constrain the launching mechanism we studied the structure of
stellar jets both over large scales and near the source where the acceleration and collimation
processes take place.
Maria Letizia Pumo
INAF – Osservatorio Astrofisico di Catania
M.L. Pumo, L. Siess, R.A. Zappalà
Advanced evolution and final fate of Super-AGB stars
Stars having initial masses between ~ 7 and ~ 11 M0 (so-called Super-AGB stars) fill the gap
between “intermediate-mass” stars unable to ignite core C-burning and “massive” stars able to
evolve through all nuclear burning stages.
As a consequence these stars exhibit a very peculiar structural evolution, characterised by offcentre C-igniton folowed by the propagation of a deflagration C-burning front to the centre. After
the C-burning phase, Super-AGB stars can end their life either forming a neon-oxygen white
dwarf or going through electro-capture supernova becoming a neutron star.
Key questions, concerning the advanced (post-He-burning) evolution and the final fate of these
starts, have not yet been explicitly investigated.
We address this issue based on the full computation of 90 stellar models, analysing the effects
of initial composition, mass loss and convective overshooting.
Preliminary results will be presented.
Lara Sidoli
INAF / IASF - Milano
Recenti scoperte sulle binarie X di grande massa
Presenterò le ultime scoperte riguardo le stelle binarie X di grande massa, focalizzandomi su
una nuova classe di sorgenti con emissione X concentrata in eventi transienti di breve durata,
dell’ordine di qualche ora o pochi giorni.
Maurizio Ternullo
INAF – Osservatorio Astrofisico di Catania
Macchie solari e oscillazioni torsionali
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Elena Tundo
Università di Padova
SMBH Mass Function from velocity dispersion and luminosity
Black hole masses are tightly correlated with the stellar velocity dispersion of host galaxies, and
slightly less-well correlated with the bulge luminosities. There is still debate on which of these
predictors can better reproduce the local black hole mass function when coupled with an
appropriate distribution function: the Mbh-&#61555;sigma relation predicts fewer massive black
holes than does the Mbh-L relation. This is because the L-sigma in black hole samples currently
available is inconsistent with that in the samples from which the distributions of L or
sigma&#61555; are based. This suggests that current black hole samples are biased towards
objects with abnormally large &#61555; for their luminosities. Assuming that the bias is a
selection rather than physical effect, then the Mbh-&#61555;sigma and Mbh-L relations
currently in the literature are also biased from their true values. Our analysis suggests that the
bias in the Mbh-&#61555;sigma relation is likely to be small, whereas the Mbh-L relation is
biased towards predicting more massive black holes for a given luminosity. In this case, the
velocity dispersion-based estimate of the intrinsic local supermassive black hole mass function
is more reliable.
Delia Volpi
Dipartimento di Astronomia - Università di Firenze
Simulated synchrotron and Inverse Compton emission from Pulsar Wind Nebulae
Basing on the set of MHD equations and the evolution equation of the maximum energy of the
emitting particles (which includes adiabatic and synchrotron losses along streamlines) a
complete set of diagnostic tools aimed at producing synthetic synchrotron emissivity, integrated
flux energy, polarization and spectral index maps from relativistic MHD simulation is obtained.
A first application of this method is the emission from Pulsar Wind Nebulae (PWNe).
Axisymmetric simulations of PWNe obtained with the relativistic MHD code by Del Zanna et
al.(2003) are directly compared with the observations of the inner structure of Crab Nebula and
similar objects in the optical and X-ray bands. The typical observed PWNe jet-torus morphology
is well reproduced even in finer emission details (arcs, rings and the bright knot) and in the
velocity ranges. Spectral properties (spectral index maps and integrated spectra) are
reproduced.
A preliminary work about Inverse Compton on CMB and synchrotron photon fields (SSC) has
been done. Some scattered radiation emissivity and integrated flux energy maps are obtained.