Dynamics of narrow, super-critical filaments within a dense core Anika Schmiedeke MPE, Garching, DE
Filaments are ubiquitous in the interstellar medium. In dust emission especially the Herschel Space Observatory revealed elongated parsec-scale filamentary structures. Along and at the junctions of these filaments, dense cores -- the birthplaces of stars -- are forming. We present two narrow and super-critical filaments embedded in a dense core. The filaments are only ~0.24 and 0.31 pc long, and have a width < 0.05 pc. Their average mass per unit length are a factor of ~3 higher than the critical mass for a 10 K isothermal cylinder (18 Msun/pc), while locally it can reach values as high as 100 Msun/pc. The non-thermal linewidths are subsonic (M < 0.5) for the entire filaments. This means that neither thermal pressure nor turbulence provide sufficient support against gravitational collapse. Hence the filaments are very unstable or require some extra level of support. Embedded in the filaments we find signs of ongoing fragmentation: A single Class I young stellar object and at least three condensations are forming a wide- separation bound system. Using multi-tracer interferometric observations, we follow the kinematics onto the filaments as well as along the filament onto the condensations, which shows "chemically fresh" material flowing on the filament. Although previous studies showed evidence for accretion onto the filaments, this is the first time such high angular resolution chemical differentiation is seen. This allows for a more dynamic picture of the evolution of dense condensations within and via narrow filaments.
Caption: (a) Integrated intensity map of NH3(1,1). The navy contour indicates the extent of the subsonic zone. The grey contours indicate the structures identified using astrodendro. The orange star and circles mark the location of the protostar and the three gas condensations, respectively. The yellow and orange arrows indicate the spine of the filaments. (b) Mass per unit length along the spine of the filaments. The blue horizontal line marks the critical mass for an isothermal 10 K cylinder (18 Msun/pc; Ostriker 1964). The yellow dashed and orange dotted horizontal line mark the average values. (c) Moment 1 map of HC3N(10-9), a tracer of "chemically fresh" material, showing velocity gradients with respect to the filament and the embedded gas condensations. The black contour show the NH3 integrated intensity. The black star and circles mark the location of the protostar and the three gas condensations, respectively.
Collaborators: J.E. Pineda, MPE, DE P. Caselli, MPE, DE	Suggested Session: Cores