Survey of Orion Disks with ALMA (SODA). II. UV-driven disk mass loss in L1641 and L1647

Context. External far-ultraviolet (FUV) irradiation of protoplanetary disks has an important impact on their evolution and ability to form planets. However, nearby (< 300 pc) star-forming regions lack sufficiently massive young stars, while the Trapezium cluster and NGC 2024 have complicated star-formation histories and their O-type stars' intense radiation fields (> 10⁴ G₀) destroy disks too quickly to study this process in detail.
Aims: We study disk mass loss driven by intermediate (10 − 1000 G₀) FUV radiation fields in L1641 and L1647, where it is driven by more common A0- and B-type stars.
Methods: Using the large (N = 873) sample size offered by the Survey of Orion Disks with ALMA (SODA), we searched for trends in the median disk dust mass with FUV field strength across the region as a whole and in two separate regions containing a large number of irradiated disks.
Results: For radiation fields between 1 − 100 G₀, the median disk mass in the most irradiated disks drops by a factor ∼2 over the lifetime of the region, while the 95th percentile of disk masses drops by a factor 4 over this range. This effect is present in multiple populations of stars, and localized in space, to within 2 pc of ionizing stars. We fitted an empirical irradiation - disk mass relation for the first time: M_dust,median = −1.3_−0.13^+0.14 log₁₀(F_FUV/G₀) + 5.2_−0.19^+0.18.
Conclusions: This work demonstrates that even intermediate FUV radiation fields have a significant impact on the evolution of protoplanetary disks.