Le 14 novembre 2014
De 10h30 à 12h00
Sacha HONY
Institute of Theoretical Astrophysics, ZAH, University of Heidelberg
The rate with which interstellar gas is converted into stars, and its dependence on environment, is one of the pillars on which our understanding of the visible Universe is build. Constraining this requires studies over a range of size-scales from parsec to hundreds of parsecs, because stars are not born in isolation, but rather in group and even groupings-of-groups. For galaxy averaged values there are successful scaling relations (Schmidt-Kennicutt relations) which connect the mean surface density of gas and the star formation rate. However, linking those averaged values to the much smaller spatial scales of the regions in which star formation actually occur proves to be non-trivial. There are only a few observational studies that address the distribution of young stars and gas over the size-interval of interest. I will present a direct comparison of the way the young stars and the dust and gas are distributed across N66, the most active star-formation site in the Small Magellanic Cloud. N66 is of particularly interest, since it hosts a range of different environments including a rich clustered environment with over 2000 possible members and a more dispersed component extending over ~80pc. I will discuss the derivation of this bimodal distribution of pre-main-sequence stars based on the observed auto-correlation function. I will further present the first measurements the Schmidt-Kennicutt relation and local star-formation efficiency across an entire star-formation complex. Our measurements are based on individual star-counts and dust column densities obtained using Spitzer, Herschel and infrared to sub-millimetre photometry. This allows us to measure star formation efficiencies on scales of ~6 parsecs which brings to light a clearly higher star formation efficiency in the clustered environment compared to the periphery.