Browsing by Author "Santangelo, G."

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    Integral-field near-infrared spectroscopy of two blue dwarf galaxies: NGC 5253 and He 2-10
    (EDP SCIENCES S A, 2010) Cresci, G.; Vanzi, L.; Sauvage, M.; Santangelo, G.; van der Werf, P.
    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]/Br gamma and H(2) line ratios, some regions corresponding to non-thermal radio sources show a [FeII]/Br gamma 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 H(2) 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 similar to 30-80 km s(-1), driven by the high star-formation activity.
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    Resolving the molecular environment of super star clusters in Henize 2-10
    (EDP SCIENCES S A, 2009) Santangelo, G.; Testi, L.; Gregorini, L.; Leurini, S.; Vanzi, L.; Walmsley, C. M.; Wilner, D. J.
    Context. The rate of star formation both in the Galaxy and in external galaxies should be related to the physical properties of the molecular clouds from which stars form. This is expected for the starbursts found both in irregular galaxies and in some mergers. The dwarf galaxy Henize 2-10 is particularly interesting in this context as it shows a number of newly formed super star clusters (SSCs) associated with a very rich molecular environment.