HP2 Survey

V. Ophiuchus: Filament formation in a dispersing cloud complex

¹ University of Vienna, Department of Astrophysics, Türkenschanzstrasse 17, 1180 Vienna, Austria
² University of Milan, Department of Physics, via Celoria 16, 20133 Milan, Italy
³ Harvard-Smithsonian Center for Astrophysics, Mail Stop 72, 60 Garden Street, Cambridge, MA 02138, USA

^★ Corresponding author.

Received: 5 November 2024
Accepted: 22 December 2024

Abstract

We searched for potential “birthmarks” left from the formation of filamentary molecular clouds in the Ophiuchus complex. We used high dynamic range column density and temperature maps derived from Herschel, Planck, and 2MASS/NICEST extinction data. We found 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 the two 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.