The Pipe Nebula as seen with Herschel: Formation of filamentary structures by large-scale compression ?

TL;DR

This study uses Herschel observations to explore how large-scale compression from nearby stellar winds influences the formation and structure of filaments in the Pipe Nebula, a key process in star formation.

Contribution

It provides new evidence that large-scale compression plays a significant role in filament formation in the Pipe Nebula, complementing gravitational effects.

Findings

Filaments are organized and asymmetric, indicating external compression.

Western side of the nebula shows signs of being compressed by stellar winds.

Star formation in B59 is likely triggered by this compression.

Abstract

A growing body of evidence indicates that the formation of filaments in interstellar clouds is a key component of the star formation process. In this paper, we present new Herschel PACS and SPIRE observations of the B59 and Stem regions in the Pipe Nebula complex, revealing a rich, organized network of filaments. The asymmetric column density profiles observed for several filaments, along with the bow-like edge of B59, indicates that the Pipe Nebula is being compressed from its western side, most likely by the winds from the nearby Sco OB2 association. We suggest that this compressive flow has contributed to the formation of some of the observed filamentary structures. In B59, the only region of the entire Pipe complex showing star formation activity, the same compressive flow has likely enhanced the initial column density of the clump, allowing it to become globally gravitationally unstable. Although more speculative, we propose that gravity has also been responsible for shaping the converging filamentary pattern observed in B59. While the question of the relative impact of large-scale compression and gravity remains open in B59, large-scale compression appears to be a plausible mechanism for the initial formation of filamentary structures in the rest of the complex