Grain Alignment and Rotational Disruption by Radiative Torques in Exoplanet Atmospheres

Abstract Dust clouds are ubiquitous in the atmospheres of hot Jupiters and affect their observable properties. The alignment dust grains resulting polarization provide a promising way to study magnetic fields exoplanets. Moreover, grain size distribution plays an important role physical chemical processes atmospheres, which rather uncertain. In this paper, we first by radiative torques (RATs). We find that silicate can be aligned RATs with ( B − RAT) due strong Jupiters, but carbonaceous diamagnetic material tend radiation direction k RAT). At low altitude r < 2 R p , where is planet radius, only large aligned, tiny ∼ 0.01 μ m at high > 3 . then rotational disruption RAT (RAT-D) mechanism. disrupted RAT-D into smaller sizes. Grains tensile strength lower altitude. suggest ones facilitate escaping altitudes gravity may explain presence high-altitude as well superpuff atmospheres.