Effect of Dust Rotational Disruption by Radiative Torques and Implications for F-corona decrease revealed by the Parker Solar Probe

Abstract

The first-year results from the Parker Solar Probe (PSP) reveal a gradual decrease of F-coronal dust from distances of $D=0.166-0.336$ AU (or the inner elongations of $\sim 9.22-18.69R_{\odot }$) to the Sun (Howard et al. 2019). Such a F-corona decrease cannot be explained by the dust sublimation scenario of the popular silicate composition that implies a dust-free-zone of boundary at heliocentric radius $R\lesssim 4-5R_{\odot }$, but may be explained by appealing to various dust compositions with different sublimation fronts. In this paper, we present an additional explanation for the F-corona decrease using our newly introduced mechanism of dust destruction so-called Radiative Torque Disruption (RATD) mechanism. We demonstrate that RATD rapidly breaks large grains into nanoparticles so that they can be efficiently destroyed by nonthermal sputtering induced by bombardment of energetic protons from slow solar winds, which extends the dust-free-zone established by thermal sublimation to $R_{dfz}\sim 8R_{\odot }$. Beyond this extended dust-free-zone, we find that the dust mass decreases gradually from $R\sim 42R_{\odot }$ toward the Sun due to partial removal of nanodust by nonthermal sputtering. The joint effect of RATD and nonthermal sputtering can successfully reproduce the gradual decrease of the F-corona between $19-9R_{\odot }$ observed by the PSP. Finally, the RATD mechanism can efficiently produce nanoparticles usually observed in the inner solar system.

arXiv comment14 pages, 7 figures, accepted to ApJ

References in corpus (25)

• Electric Dipole Radiation from Spinning Dust Grains
• Radiative torques: Analytical Model and Basic Properties
• Radiative Torques on Interstellar Grains: I. Superthermal Spinup
• Dust sublimation by GRBs and its implications
• Radiative torque alignment: Essential Physical Processes
• A unified model of grain alignment: radiative alignment of interstellar grains with magnetic inclusions
• Grain Alignment by Radiative Torques in Special Conditions and Implications
• Rotational Disruption of Dust Grains by Radiative Torques in Strong Radiation Fields
• Improving the model of emission from spinning dust: effects of grain wobbling and transient spin-up
• Subsonic Mechanical Alignment of Irregular Grains
• Sublimation Temperature of Circumstellar Dust Particles and Its Importance for Dust Ring Formation
• Alignment of Irregular Grains by Mechanical Torques
• Radiative torques alignment in the presence of pinwheel torques
• A dynamical constraint on interstellar dust models from radiative torque disruption
• Spinning Dust Emission: Effects of irregular grain shape, transient heating and comparison with WMAP results
• Solar-wind predictions for the Parker Solar Probe orbit
• Tensile Strength of Porous Dust Aggregates
• Magnetic Properties of Dust Grains, Effect of Precession and Radiative Torque Alignment
• The tensile strength of dust aggregates consisting of small elastic grains: Constraints on the size of condensates in protoplanetary disks
• Alignment and rotational disruption of dust
• Radiative torques of irregular grains: Describing the alignment of a grain ensemble
• On origin and destruction of relativistic dust and its implication for ultrahigh energy cosmic rays
• Alignment of irregular grains by radiative torques: efficiency study
• Rotational Desorption of Ice Mantles and Complex Molecules from Suprathermally Rotating Dust Grains around Young Stellar Objects
• Rotational disruption of dust grains by mechanical torques for high-velocity gas-grain collisions