EPoS Contribution
EPoS Contribution
Wispy features in the Milky Way: a global view of filamentary structures in the Galactic Plane

Eugenio Schisano
The last years have seen a gradual, but steady, increase of interest toward the earlier stages of star formation driven by the availability of high-sensitivity and high-resolution observations at infrared/mm wavelengths. Particular attention has been paid on characterizing the inital seeds of star formation and their surrounding enviroment. Not surprisingly, there are several hints of a connection between intermediate-scale substructures of molecular clouds and pre/protostellar condensations. These substructures, but often the overall molecular cloud itself, have a filamentary shape. Filaments are extremely recurrent and represent a dominant morphology all the Galaxy: from single isolated to multiple nesting objects, from faint and tenuous to bright and dense structures. Furthermore, they are observed over a wide range of scales, from about 0.01 to 10 pc, always associated with young stars or star precursors. Several questions arise from such an overwhelming richness: Can we determine the reasons behind such a variety? Do they inherit measurable properties allowing us to identify the physical process that formed them? What is the filament role in the star formation? Do they really represent an intermediate, eventually stable, configuration between large molecular clouds and clumps/cores? Are they strictly necessary to form stars? With such an increasing interest of community on filamentary structures, it is important to physically characterize an unbiased sample of filaments embedded in different enviroments. In this work I present a robust sample of more than 2000 elongated, filamentary-like objects selected from a larger list of almost 30000 candidates identified on Herschel dust continuum maps all along the Milky Way. The filaments in the robust sample lie between galactic longitudes 20 and 55 degrees and are confirmed as velocity-coherent features through detailed analysis of Galactic Ring Survey 13CO line data. The classification of remaining candidates is currently ongoing as part of VIALACTEA project by means of available molecular line datasets. We measure masses, densities, mean temperatures, lengths, widths, velocity gradients along the structure, occurence of local star formation activity, etc., for most objects in the robust sample. Such a statistical sample allows us to test the universality of the new, recently proposed, paradigm of star formation in which filamentary shapes have a fundamental role. Finally, we investigate the relation between the turbulent state of interstellar medium and the galactic distribution of filaments to shed light on over the process that form them.
S. Molinari, INAF-IAPS, IT
M. Benedettini, INAF-IAPS, IT
S. Pezzuto, INAF-IAPS, IT
M. Merello, INAF-IAPS, IT
A. Di Giorgio, INAF-IAPS, IT
and VIALACTEA team
Suggested Session: Filaments