|The earliest phases of star formation: From low- to high-mass objects
|Present-day star formation starts in the coldest and densest cores of molecular clouds. Still, our knowledge about the very early stages of star formation is limited. Objects at these stages emit most of their luminosity at FIR wavelengths, which is not observable from the ground. Hence, our view in this wavelength range to date remains fuzzy at best, since all available information from the FIR is generally obtained from small aperture satellites severely lacking spatial resolution. Therefore, data are strongly affected by source blending, especially within protoclusters, where the density of potential protostars is very high. This limits the derivation of core masses and density profiles which is a major drawback for detailed studies of young low-mass cores. In addition, it has severely hampered progress in characterising young and cold high-mass cores which are, on average, far more distant. Nevertheless, detailed knowledge about these pre- and protostellar stages is indispensable for answering fundamental questions about the physics of the early collapse phase, the core fragmentation and the general ways to finally form stars of all masses. With Herschel we have the unique opportunity to deeply scrutinise such cold cradles of stars with unprecedented sensitivity and angular resolution in the FIR. We therefore propose to use the PACS and SPIRE instruments to perform deep and directed FIR mapping of confined regions. We have compiled a unique sample of low and high-mass targets that we identified based on careful preparatory studies (including ISO and Spitzer observations) as very promising sources for the study of initial conditions of star formation. The Herschel data will allow us to reconstruct the (3D) density and temperature structure and assess the energy budget of the cores. Furthermore, Herschel will for the first time enable us to perform an advanced modelling of such cold cores that is not affected by simplifications and parameter ambiguities.
|The Earliest Phases of Star Formation (EPoS): a Herschel key program. The precursors to high-mass stars and clusters . Ragan S. et al. . Astronomy & Astrophysics, Volume 547, id.A49, 79 pp. . 547 . 10.1051/0004-6361/201219232 . 2012A&A...547A..49R ,
|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, 2011, KPGT_okrause_1, SPG v14.2.0. https://doi.org/10.5270/esa-5z0lxy9