Evolution of spheroidal dust in electrically active sub-stellar atmospheres

Stark, Craig R.; Diver, D. A.

doi:10.1051/0004-6361/202037589

Cited by 2 publications

(2 citation statements)

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“…Polarization in thermal emission from giant planets is discussed in Marley & Sengupta (2011; see Marley et al 2013 for a review). A recent study by Stark & Diver (2020) suggested that if the grains are aligned, they can produce a polarization degree of order of ∼1%. Following the modern understanding of grain alignment theory, dust grains in the hot Jupiter's atmospheres subject to stellar radiation are expected to be efficiently aligned by radiative torques (RATs; Lazarian & Hoang 2007a;Hoang & Lazarian 2008.…”

Section: Introductionmentioning

confidence: 99%

Grain Alignment and Rotational Disruption by Radiative Torques in Exoplanet Atmospheres

Hoang

Lazarían

2023

ApJ

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

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Section: Introductionmentioning

confidence: 99%

Grain Alignment and Rotational Disruption by Radiative Torques in Exoplanet Atmospheres

Hoang

Lazarían

2023

ApJ

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show abstract

“…Polarization in thermal emission from giant planets is discussed in Marley & Sengupta (2011) (see Marley et al 2013 for a review). Recent study by Stark & Diver (2020) suggested that if grains are aligned, they can produce a polarization degree of orders of ∼ 1%. Following the modern understanding of grain alignment theory, dust grains in the hot Jupiter's atmospheres subject to stellar radiation can be efficiently aligned by RAdiative Torques (RATs; Lazarian & Hoang 2007;Hoang & Lazarian 2008a.…”

Section: Introductionmentioning

confidence: 99%

Grain alignment and rotational disruption by radiative torques in exoplanet atmospheres

Hoang¹,

Lazarian²

2021

Preprint

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

show abstract

Evolution of spheroidal dust in electrically active sub-stellar atmospheres

Cited by 2 publications

References 77 publications

Grain Alignment and Rotational Disruption by Radiative Torques in Exoplanet Atmospheres

Grain Alignment and Rotational Disruption by Radiative Torques in Exoplanet Atmospheres

Grain alignment and rotational disruption by radiative torques in exoplanet atmospheres

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