EPoS Contribution

Feedback-driven filament formation Joao Alves UVienna, Vienna, AT
We explore the influence of massive stars on the gas distribution in Ophiuchus, a key laboratory of star formation. We construct high-dynamic-range column density maps (from 6×10²⁰ to 6×10²³ cm^-2), and temperature maps for the Ophiuchus cloud complex, using a combination of Planck and Herschel dust emission calibrated with 2MASS NIR extinction. The main filaments in rho Ophiuchi cloud exhibit several notable characteristics: 1) they are aligned radially with massive ionizing stars in Upper-Sco; 2) have decreasing longitudinal mass profiles from their heads (facing the massive stars) to their tails; 3) the filament heads contain virtually all the protostars in the region; and 4) they are moving away from the massive stars. In contrast, the main filaments in the Oph North complex are oriented approximately orthogonal to the nearest massive star and show a relatively constant linear mass. These findings led us to measure filament orientations across the larger gas distribution around the Upper-Sco region using Planck data. Like for Ophiuchus, filament orientations are not random; instead, they tend to either be radially aligned towards the general direction of massive stars (R-type) or orthogonal to them (O-type). We suggest that both types of filaments are a result of feedback from massive stars. This illustrates a complex phase in molecular cloud evolution, characterized by two simultaneous yet contrasting processes: the formation of filaments and stars through the compression and stretching of gas and the dispersal of residual gas remaining from a previous massive star formation event in Sco-Cen. Our results imply that the formation of dense molecular filaments in the ISM is not a universal process. The filament types discussed here are likely to be only found in feedback dominated regions. Other filament types are likely to emerge under different star-forming conditions.

Caption: Temperature map of the well-known Ophiuchus-Lupus-Pipe region. Areas in white indicate dust at approximately 30 K at the center of the image, while black areas represent dust at cooler temperatures, around 10 K. The main gas filaments in the region are easily distinguishable as colder structures and are highlighted with orange rectangles. Notably, the orientations of these filaments are not arbitrary (top left: distribution of filament orientations). They typically align either radially towards the direction of massive stars (classified as R-type) or at right angles to them (O-type). The feedback from the 20 ionizing massive stars in the Upper-Sco region plays a crucial role in forming and shaping these filaments and driving the star formation in the region.
Collaborators: M. Lombardi, UMilan, IT C. Lada, CfA, US	Key publication Relevant topic(s): Feedback Filaments Molecular Clouds
Relevant Big Question: Is the formation of star-forming filaments a universal process?