Evolution of HDO/H2O in Protoplanetary Disks During Accretion Outbursts: Model Predictions for FU Orionis Systems

Title:Evolution of HDO/H2O in Protoplanetary Disks During Accretion Outbursts: Model Predictions for FU Orionis Systems

Authors:Anastasiia Topchieva, Tamara Molyarova and Anton Vasyunin

Conference:APRIM2026

Tags:astrochemistry, interplanetary medium and protoplanetary disks

Abstract:

First astrochemical study of FU Ori outbursts affecting water ice deuteration in disks, addressing ALMA data of V883 Ori. Anomalies: high HDO/H₂O & snowline at ~80 au, inconsistent with current ~400 L⊙.

Using ANDES code, we modeled a V883 Ori-like disk under 400–10,000 L⊙ outbursts (full D-chemistry, 2D disk, envelope). Key findings:

Amplitude critical:400 L⊙ fails (snowline ~20–30 au). 2000–10,000 L⊙ matches HDO/H₂O at 40–140 au & snowline 60–100 au.

Fossil record:Gas-phase HDO/H₂O reflects pre-existing ice. High deuteration = fingerprint of cold ice sublimated by past heating.

V883 Ori scenario:Best fit = past ~10,000 L⊙ outburst. Signature persists after weaker ~400 L⊙, explaining current low luminosity & primitive disk.

Thermal sensitivity:400 L⊙ could work with steeper midplane T∝R⁻³/⁷, highlighting need for accurate thermal structure.

Conclusion:Water deuteration is a sensitive archive of episodic accretion. V883 Ori data favor a giant past burst, supporting the inheritance scenario (high-D ice forms in cold ISM, survives into disk). This links stellar accretion history to planet-forming material chemistry, impacting our understanding of water's origin in planetary systems.