HP2 Survey V. Ophiuchus: Filament formation in a dispersing cloud complex

TL;DR

This study investigates filament formation in the Ophiuchus molecular cloud complex, identifying two filament types influenced by massive star outflows, and highlights how these processes shape cloud evolution and star formation.

Contribution

It introduces a new classification of filaments based on orientation and formation mechanisms driven by star outflows, emphasizing the complex dynamics of cloud dispersal.

Findings

Identification of two filament types: R-type and T-type.

Distinct mass profiles linked to filament orientation.

Filament formation driven by outflow-induced compression and stretching.

Abstract

We search for potential ``birthmarks'' left from the formation of filamentary molecular clouds in the Ophiuchus complex. We use high dynamic-range column density and temperature maps derived from \textit{Herschel}, \textit{Planck}, and \textit{2MASS/NICEST} extinction data. We find two distinct types of filaments based on their orientation relative to nearby massive stars: radial (R-type) and tangential (T-type). R-type filaments exhibit decreasing mass profiles away from massive stars, while T-type filaments show flat but structured profiles. We propose a scenario where both filament types originate from the dynamic interplay of compression and stretching forces exerted by a fast outflow emanating from the OB association. The two formation mechanisms leave distinct observable ``birthmarks'' (namely, filament orientation, mass distribution, and star formation location) on each filament type. Our results illustrate a complex phase in molecular cloud evolution with two simultaneous yet contrasting processes: the formation of filaments and stars via the dispersal of residual gas from a previous massive star formation event. Our approach highlights the importance of taking into account the wider context of a star-forming complex, rather than concentrating exclusively on particular subregions.