Morphology and Kinematics of Filaments in the Serpens and Perseus Molecular Clouds

TL;DR

This study uses high-resolution molecular line observations to analyze the structure and kinematics of filaments in the Serpens and Perseus molecular clouds, revealing detailed morphology, velocity gradients, and support for filament formation models.

Contribution

It provides high-resolution maps of dense gas tracers in filaments, uncovering complex velocity structures and supporting models of filament formation by turbulent inflow.

Findings

Filaments have widths of 0.03-0.08 pc.

Over 50% of filaments show perpendicular velocity gradients.

Evidence of inflow along some filaments towards cloud cores.

Abstract

We present H13CO+ (J=1-0) and HNC (J=1-0) maps of regions in Serpens South, Serpens Main and NGC 1333 containing filaments. We also observe the Serpens regions using H13CN (J=1-0). These dense gas tracer molecular line observations carried out with CARMA have an angular resolution of ~7", a spectral resolution of ~0.16 km/s and a sensitivity of 50-100 mJy/beam. Although the large scale structure compares well with the Herschel dust continuum maps, we resolve finer structure within the filaments identified by Herschel. The H13CO+ emission distribution agrees with the existing CARMA N2H+ (J=1-0) maps; so they trace the same morphology and kinematics of the filaments. The H13CO+ maps additionally reveal that many regions have multiple structures partially overlapping in the line-of-sight. In two regions, the velocity differences are as high as 1.4 m/s. We identify 8 filamentary structures having typical widths of 0.03-0.08 pc in these tracers. At least 50% of the filamentary structures have distinct velocity gradients perpendicular to their major axis with average values in the range 4-10 km/s/pc. These findings are in support of the theoretical models of filament formation by 2-D inflow in the shock layer created by colliding turbulent cells. We also find evidence of velocity gradients along the length of two filamentary structures; the gradients suggest that these filaments are inflowing towards the cloud core.