|Unveiling the spectral shape of warm Galactic dust emission
|The largest dust grains dominate the total dust mass, as well as the observed emission in the far-infrared (FIR) domain. They contribute to the efficient cooling in the FIR and submillimeter-millimeter (submm-mm) wavelengths, essential for the condensation of the ISM and the star formation process. Understanding the variations in dust emissivity is of primary importance, because they directly affect the accuracy of any mass determination using the Herschel photometric data. They are also extremely interesting in the prospect of understanding dust physics. For long time, the lack of data in the submm domain has induced to model the submm dust emission by a modified black-body, characterized by the mean dust temperature and a temperature and wavelength independent spectral index. However, analyses of recent data have shown a significant flattening of the dust emission spectrum in the submm-mm domain, for temperatures around 20 K. Emissivity variations also seem to be temperature-dependent. Two main models of the FIR-submm emission have been proposed to explain astrophysical observations, leading to different estimates of the interstellar medium characteristics. The present proposal aims at obtaining Herschel low resolution spectroscopic data towards the warmest regions of the ISM, in order to measure precisely their dust continuum emission. Indeed, dust processes occuring in warm-hot environments are poorly known. This unique combination of PACS and SPIRE spectroscopy for a sample of 7 compact-ultra-compact HII regions, accounting for 15.4h observing time, will allow us to efficently discrimate between possible dust models.
|Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
|Publisher And Registrant
|European Space Agency
|European Space Agency, 2013, OT2_dparadis_2, SPG v14.2.0. https://doi.org/10.5270/esa-dexyk9e