Luminosity outburst chemistry in protoplanetary discs: going beyond standard tracers

Abstract

The chemical influence of luminosity outbursts on the environments of young solar-type stars is explored. Species are categorised into several types according to their response to the outburst. The first and second types imply chemical changes only during the outburst (with slightly different behaviours). These response types are mostly observed close to the star and are caused by icy mantle evaporation. However, mantles recover after the outburst almost immediately. A notable exception is benzene ice, which is accumulated on dust surfaces during and after the outburst, so that its abundance exceeds the pre-outburst level by orders of magnitude. The third type of response is mostly seen at the disc periphery and implies alteration of abundances during the outburst and preservation of these `abnormal' abundances for centuries. This behaviour is typical of organic compounds, like HCOOCH${}_3$, CH${}_3$CN, CH${}_2$CO. Their presence in the dark disc regions can be a manifestation of the past outburst. CO and CO${}_2$ only trace past outbursts at the remote disc regions. The outburst changes the C/O ratio, but it quickly returns to the pre-outburst value almost everywhere in the disc. An important factor determining the sensitivity of molecular composition to the outburst is the dust size distribution. The duration of the pre-outburst stage and of the outburst itself influence the chemical effects, if the burst duration is shorter than 50 yr and the duration of the quiescent phase between the bursts is shorter than 100 kyr.

Accepted to MNRAS

References in corpus (15)

• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• The 2014 KIDA network for interstellar chemistry
• The Burst Mode of Protostellar Accretion
• Variable protostellar accretion with episodic bursts
• On the existence of accretion-driven bursts in massive star formation
• Thermal desorption of circumstellar and cometary ice analogs
• Decoupling of Magnetic Fields in Collapsing Protostellar Envelopes and Disk Formation and Fragmentation
• Cometary ices in forming protoplanetary disc midplanes
• Molecule sublimation as a tracer of protostellar accretion: Evidence for accretion bursts from high angular resolution C18O images
• Chemical tracers of episodic accretion in low-mass protostars
• The chemistry of protoplanetary fragments formed via gravitational instabilities
• The chemistry of episodic accretion in embedded objects. 2D radiation thermo-chemical models of the post-burst phase
• Gas mass tracers in protoplanetary disks: CO is still the best
• V346 Normae: First post-outburst observations of an FU Orionis star
• Mass transport from the envelope to the disk of V346 Nor: a case study for the luminosity problem in an FUor-type young eruptive star

Cited by in corpus (15)

• Accretion bursts in magnetized gas-dust protoplanetary disks
• Evolution of dust in protoplanetary disks of eruptive stars
• Collisional evolution of dust and water ice in protoplanetary discs during and after an accretion outburst
• Accretion bursts in high-mass protostars: a new testbed for models of episodic accretion
• Burned to ashes: How the thermal decomposition of refractory organics in the inner protoplanetary disc impacts the gas-phase C/O ratio
• ALMA observations of the Extended Green Object G19.01$-$0.03: I. A Keplerian disc in a massive protostellar system
• Physical and Chemical Structure of the Disk and Envelope of the Class 0/I Protostar L1527
• Gaia21bty: An EXor lightcurve exhibiting an FUor spectrum
• The warm-up phase in massive star-forming cores around RCW 120
• Modeling snowline locations in protostars: The impact of the structure of protostellar cloud cores
• Star formation timescale in the molecular filament WB 673
• Time-dependent response of protoplanetary disk temperature to an FU Ori-type luminosity outburst
• Gaia20bdk -- a new FUor in Sh 2-301 Star Forming Region
• Gas-phase and Surface Chemistry in the Massive Star-Forming Region RCW\,120
• Infrared observations of the flaring maser source G358.93-0.03 -- SOFIA confirms an accretion burst from a massive young stellar object