Rapid destruction of protoplanetary discs due to external photoevaporation in star-forming regions

• We analyse N-body simulations of star-forming regions to investigate the effects of externalfar- and extreme-ultraviolet photoevaporation from massive stars on protoplanetary discs. Byvarying the initial conditions of simulated star-forming regions, such as the spatial distribution,net bulk motion (virial ratio), and density, we investigate which parameters most affect the rateat which discs are dispersed due to external photoevaporation. We find that disc dispersal due toexternal photoevaporation is faster in highly substructured star-forming regions than in smoothand centrally concentrated regions. Subvirial star-forming regions undergoing collapse alsoshow higher rates of disc dispersal than regions that are in virial equilibrium or are expanding.In moderately dense (∼100 M pc −3 ) regions, half of all protoplanetary discs with radii≥100 au are photoevaporated within 1 Myr, three times faster than is currently suggested byobservational studies. Discs in lower density star-forming regions (∼10 M pc −3 ) survive forlonger, but half are still dispersed on short time-scales (∼2 Myr). This demonstrates that theinitial conditions of the star-forming regions will greatly impact the evolution and lifetime ofprotoplanetary discs. These results also imply that either gas giant planet formation is extremelyrapid and occurs before the gas component of discs is evaporated, or gas giants only formin low-density star-forming regions where no massive stars are present to photoevaporate gasfrom protoplanetary discs.

Subject headings

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Publication and Content Type

art (subject category)

ref (subject category)