Rotational Desorption of Ice Mantles and Complex Molecules from Suprathermally Rotating Dust Grains around Young Stellar Objects

Abstract

Ice mantles on dust grains play a central role in astrochemistry. Water and complex organic molecules (COMs) are thought to first form on the ice mantles and subsequently are released into the gas phase due to star formation activity. However, the critical question is whether ice mantles can survive stellar radiation when grains are being heated from $T_d\sim 10\mathrm{K}$ to $\gtrsim 100$ K. In this paper, we first study the effect of suprathermal grain rotation driven by the intense radiation of young stellar objects (YSOs) on the ice mantles. We find that the entire ice mantles can be disrupted into small fragments by centrifugal stress before the water ice and COMs desorb via thermal sublimation. We then study the consequence of resulting ice fragments and find that tiny fragments of radius $a\lesssim 10$Å~ exhibit transient release of COMs due to thermal spikes, whereas larger fragments can facilitate thermal sublimation at much higher rates than from the original icy grain or the same rate but with temperatures of $\sim 20-40$ K lower. We find that rotational desorption is efficient for hot cores/corinos from the inner to outer regions where the temperature drops to $T_{\mathrm{gas}}\sim 40\mathrm{K}$ and $n_{\mathrm{H}}\sim 10^4\mathrm{c}{\mathrm{m}}^{-3}$. We discuss the implications of this mechanism for desorption of COMs and water ice in various environments, including outflow cavity walls, photodissociation regions, and protoplanetary disks. Finally, we show that very large aggregate grains can be disrupted into individual icy grains via rotational disruption mechanism, followed by rotational desorption of ice mantles.

17 pages, 11 figures; accepted to ApJ

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• A statistical analysis of dust polarization properties in ALMA observations of Class 0 protostellar cores
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• The water-ice feature in near-infrared disk-scattered light around HD 142527: Micron-sized icy grains lifted up to the disk surface?
• Icy molecule desorption in interstellar grain collisions
• Variation of dust properties with cosmic time implied by radiative torque disruption
• Observational evidence for rotational desorption of Complex Molecules by radiative torques from Orion BN/KL
• Scattering polarization of 3-$\mu$m water-ice feature by large icy grains
• Physical conditions for dust grain alignment in Class 0 protostellar cores II. The role of the radiation field in models aligning/disrupting dust grains
• Effect of Dust Rotational Disruption by Radiative Torques and Implications for F-corona decrease revealed by the Parker Solar Probe
• The radiative torque spin-up efficiency of ballistic dust grain aggregates
• Evolution of Dust and Water Ice in Cometary Comae by Radiative Torques
• On planet formation around supermassive black holes and the grain disruption barriers by radiative torques
• Grain alignment and dust evolution physics with polarisation (GRADE-POL). I. Dust polarisation modelling for isolated starless cores
• Rotational Disruption of Dust and Ice by Radiative Torques in Protoplanetary Disks and Implications for Observations
• Effect of dust rotational disruption by radiative torques on radiation pressure feedback from massive protostars
• Constraining properties of dust formed in Wolf-Rayet binary WR 112 using mid-infrared and millimeter observations