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

Abstract

External 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>10^4\,G_0) destroy disks too quickly to study this process in detail. We study disk mass loss driven by intermediate (10 - 1000 G0G_0) FUV radiation fields in L1641 and L1647, where it is driven by more common A0 and B-type stars. Using the large (N=873) sample size offered by the Survey of Orion Disks with ALMA (SODA), we search 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. For radiation fields between 1 - 100 G0G_0, the median disk mass in the most irradiated disks drops by a factor ∼2\sim 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 fit an empirical irradiation - disk mass relation for the first time: Mdust,median=βˆ’1.3βˆ’0.13+0.14log⁑10(FFUV/G0)+5.2βˆ’0.19+0.18M_{\rm{dust,median}} = -1.3^{+0.14}_{-0.13} \log_{10}(F_{\rm{FUV}} / G_0) + 5.2^{+0.18}_{-0.19}. This work demonstrates that even intermediate FUV radiation fields have a significant impact on the evolution of protoplanetary disks.Comment: Accepted to A&A Letters. 5 pages, 4 figure

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