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

TL;DR

This study uses ALMA observations to analyze how intermediate FUV radiation fields from nearby stars influence the mass loss and evolution of protoplanetary disks in the Orion region, revealing significant effects even at moderate radiation levels.

Contribution

It provides the first empirical relation between FUV irradiation strength and median disk dust mass, highlighting the impact of intermediate radiation fields on disk evolution.

Findings

Median disk mass decreases by a factor of 2-4 with increasing FUV flux.

Disk mass loss is localized within 2 pc of ionizing stars.

Established an empirical relation between FUV flux and disk dust mass.

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 ($>10^4\,G_0$) destroy disks too quickly to study this process in detail. We study disk mass loss driven by intermediate (10 - 1000 $G_0$) 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 $G_0$, the median disk mass in the most irradiated disks drops by a factor $\sim 2$ 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: $M_{\rm{dust,median}} = -1.3^{+0.14}_{-0.13} \log_{10}(F_{\rm{FUV}} / G_0) + 5.2^{+0.18}_{-0.19}$. This work demonstrates that even intermediate FUV radiation fields have a significant impact on the evolution of protoplanetary disks.