Kavli Affiliate: Ke Wang
| First 5 Authors: Ke Wang, Yifei Ge, Tapas Baug, ,
| Summary:
Filamentary structure is important for the ISM and star formation. Galactic
distribution of filaments may regulate the star formation rate in the Milky
Way. However, interstellar filaments are intrinsically complex, making it
difficult to study quantitatively. Here, we focus on linear filaments, the
simplest morphology that can be treated as building blocks of any filamentary
structure. We present the first catalog of 42 “straight-line” filaments
across the full Galactic plane, identified by clustering of far-IR Herschel
HiGAL clumps in position-position-velocity space. We use molecular line cubes
to investigate the dynamics along the filaments; compare the filaments with
Galactic spiral arms; and compare ambient magnetic fields with the filaments’
orientation. The selected filaments show extreme linearity ($>$10), aspect
ratio (7-48), and velocity coherence over a length of 3-40 pc (mostly $>$10
pc). About 1/3 of them are associated with spiral arms, but only one is located
in arm center, a.k.a. “bones” of the Milky Way. A few of them extend
perpendicular to the Galactic plane, and none is located in the Central
Molecular Zone (CMZ) near the Galactic center. Along the filaments, prevalent
periodic oscillation (both in velocity and density) is consistent with gas
flows channeled by the filaments and feeding the clumps which harbor diverse
star formation activities. No correlation is found between the filament
orientations with Planck measured global magnetic field lines. This work
highlights some of the fundamental properties of molecular filaments and
provides a golden sample for follow-up studies on star formation, ISM
structure, and Milky Way structure.
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