Super Star Clusters in the Blue Dwarf Galaxy UM 462

I present optical observations of the Blue Compact Dwarf Galaxy UM 462. The images of this galaxy show several bright compact sources. A careful study of these sources has revealed their nature of young Super Star Clusters. The ages determined from the analysis of the stellar continuum and $H\alpha$ are between few and few tens Myr. The total star formation taking place into the clusters is about 0.05 $\mathrm{M_{\odot}/yr}$. The clusters seem to be located at the edges of two large round-like structures, possibly shells originated in a previous episode of star formation. The sizes of the shells compare well with the ages of the clusters. Evidence for the presence of an evolved underlying stellar population is found.Comment: 8 pages, 6 figure

Integral field spectroscopy in the near infrared of NGC 3125-A and SBS 0335-052

We present integral field spectroscopy in the near infrared of the nearby dwarf starburst galaxies NGC 3125-A and of the low metallicity dwarf galaxy SBS 0335-052. The use of adaptive optics in the observations produces sub-arcsecond angular resolution. We pinpoint the star forming cores of both galaxies, identify relevant ISM components such as dust, photo ionized gas, shock excited gas and molecular gas. We relate these components to the large scale star formation process of the galaxies. In particular we find the emission of the near infrared lines of H2 and especially [FeII] does not coincide with the HII region in NGC 3125. We have the first clear detection of [FeII] in SBS 0335-052

Studio delle caratteristiche analitiche e applicative di alcuni composti organici ad azione biocida utilizzati nell'industria conciaria

Il controllo della crescita batterica e dello sviluppo di funghi e muffe, è un aspetto fondamentale in numerose fasi della lavorazione conciaria. Nella concia al cromo, questo controllo permette di conservare a lungo le pelli ed evitare difetti sul prodotto finale. Nel presente lavoro, svolto presso il laboratorio Dermacolor, sono stati valutati, dal punto di vista analitico ed applicativo, alcuni fra i principi attivi più usati nella lavorazione conciaria durante la concia al cromo. E’ stata effettuata una valutazione e comparazione dell’efficacia di diversi prodotti e tale efficacia è stata messa in relazione con la quantità di principio attivo contenuta nella pelle conciata. A partire da prodotti commerciali, è stata effettuata la purificazione di due principi attivi, i quali, sono stati caratterizzati mediante spettroscopia UV, FT-IR, 1HNMR ed impiegati come standard cromatografico nell’analisi HPLC condotta sulla pelle

Integral-field near-infrared spectroscopy of two blue dwarf galaxies: NGC 5253 and He 2-10

We present integral field spectroscopy in the near infrared (NIR) of He 2-10 and NGC 5253, two well known nearby dwarf irregular galaxies showing high star-formation rates. Our data provide an unprecedented detailed view of the interstellar medium and star formation in these galaxies, allowing us to obtain spatially resolved information from the NIR emission and absorption line tracers. We study the spatial distribution and kinematics of different components of the interstellar medium (ISM) mostly through the Bracket series lines, the molecular hydrogen spectrum, [FeII] emission, and CO absorptions. Although the ISM is mostly photo-excited, as derived by the [FeII]/Bry and H2 line ratios, some regions corresponding to non-thermal radio sources show a [FeII]/Bry excess due to a significant contribution of SN driven shocks. In He 2-10 we find that the molecular gas clouds, as traced by CO(2-1) and H2 infrared line, show consistent morphologies and velocities when studied with the two different tracers. Moreover, there is a clear association with the youngest super star clusters as traced by the ionized gas. In the same galaxy we observe a cavity depleted of gas, which is surrounded by some of the most active regions of star formation, that we interpret as a signature of feedback-induced star formation from older episodes of star formation. Finally, we measured high turbulence in the ISM of both galaxies, sigma~30-80 km/s, driven by the high star-formation activity.Comment: 12 pages, 10 figures, accepted for publication in A&

Identifying the lights position in photometric stereo under unknown lighting

Reconstructing the 3D shape of an object from a set of images is a classical problem in Computer Vision. Photometric stereo is one of the possible approaches. It stands on the assumption that the object is observed from a fixed point of view under different lighting conditions. The traditional approach requires that the position of the light sources is accurately known. It has been proved that the lights position can be estimated directly from the data, when at least 6 images of the observed object are available. In this paper, we give a Matlab implementation of the algorithm for solving the photometric stereo problem under unknown lighting, and propose a simple shooting technique to solve the bas-relief ambiguity.Comment: new versio

Delayed Photoionization Feedback in a Super Star Cluster in SBS0335-052E

SBS0335-052 is a well studied Blue Compact Dwarf galaxy with one of the lowest metallicities of any known galaxy. It also contains 6 previously identified Super Star Clusters. We combine archival HST NICMOS images in the Pa alpha line and the 1.6 micron continuum of the eastern component, SBS0335-052E, with other space and ground based data to perform a multi-wavelength analysis of the super star clusters. We concentrate on the southern most clusters, designated S1 and S2, which appear to be the youngest clusters and are the strongest emitters of Pa alpha, radio, and x-ray flux. Our analysis leads to a possible model for S1 and perhaps S2 as a cluster of very young, massive stars with strong stellar winds. The wind density can be high enough to absorb the majority of ionizing photons within less than 1000 AU of the stars, creating very compact HII regions that emit optically thick radiation at radio wavelengths. These winds would then effectively quench the photoionizing flux very close to the stars. This can delay the onset of negative feedback by photoionization and photodissociation on star formation in the clusters. This is significant since SBS0335-052E resembles the conditions that were probably common for high redshift star formation in galaxies near the epoch of reionization.Comment: Accepted for publication in the Astrophysical Journa