The ice composition in the protoplanetary disk V883 Ori revealed by its stellar outburst

Earth-like planets form mostly from dry refractory materials in the inner regions of protoplanetary disks; however, they might become habitable if water and organic molecules are delivered to their surfaces and atmospheres by planetesimals formed beyond the sublimation front of water. Complex organic molecules (COMs), which are the seeds of prebiotic material and precursors of amino acids and sugars, form in the icy mantles of dust grains but cannot be detected remotely unless they are heated and released to the gas phase. Around solar-mass stars, water and COMs only sublimate in the inner few au of the disk, making them extremely difficult to spatially resolve and study. Sudden increases in the luminosity of the central star will quickly expand the snow line to larger radii, as seen previously in the FU Ori outburst of the young star V883 Ori. In this paper, we take advantage of the rapid increase in disk temperature of V883 Ori to detect and analyze five different COMs, methanol, acetone, acetonitrile, acetaldehyde, and methyl formate, in spatially-resolved submillimeter observations. The COMs emission observed in V883 Ori traces fresh sublimates at the edges of the water sublimation front, where the disk becomes optically thin. COMs abundances in V883 Ori are much more similar to those in comets than to those in the protostellar core IRAS 16293 B, which represent older and younger evolutionary stages, respectively. The chemical evolution of COMs continues after the volatiles are incorporated to the disk and during the planet formation process. Since the duration of the stellar outbursts ($sim$100 yr) is shorter than the gas-phase chemical timescale ($sim10^4$ yr), high-resolution observations of FU Ori objects such as V883 Ori open a new and truly unique window to trace the composition and chemical evolution of ices in protoplanetary disks.