The Snake Filament: A study of polarization and kinematics

TL;DR

This study investigates how magnetic fields influence the structure and dynamics of the Snake filament in the Pipe Nebula, revealing aligned magnetic fields, velocity gradients, and stability against gravitational collapse through polarization and molecular line observations.

Contribution

It provides new insights into the magnetic field orientation and gas kinematics in the Snake filament using combined polarization and molecular line data.

Findings

Magnetic fields are aligned with the filament's spine at lower densities.

A velocity gradient along the filament indicates gas motion.

The filament is stable against gravitational collapse.

Abstract

The role of magnetic fields in the formation of dense filamentary structures in molecular clouds is critical for understanding the star formation process. The Snake filament in or close to the Pipe Nebula s neighboring, a prominent example of such structures, offers an ideal environment to study the interplay between magnetic fields and gas dynamics in the early stages of star formation. This study aims to investigate how magnetic fields influence the structure and dynamics of the Snake filament, using both polarization data and molecular line observations. Our goal is to understand the role of magnetic fields in shaping the filamentary structure and explore the kinematics within the filament. We conducted polarization observations in the optical and near-infrared bands using the 1.6 m and 60 cm telescopes at the Observatorio do Pico dos Dias/Laboratorio Nacional de Astrof\isica (OPD/LNA). Molecular line observations of the C18O and 13CO lines were obtained using the IRAM 30m telescope. We analyzed the data to characterize polarization and gas properties within the filament, with a focus on understanding the magnetic field orientation and its relationship with the filament s structure. Our findings reveal that the polarization vectors align with the filament s spine, indicating a magnetic field structure that is predominantly parallel to the filament at lower-density regions. A velocity gradient along the filament is observed in both C18O and 13CO lines, with C18O tracing the denser regions of the gas. The polarization efficiency decreases with increasing visual extinction, consistent with reduced grain alignment in higher-density regions. The filament s mass-to-length ratio is below the critical value required for gravitational collapse, indicating stability.