On the likely magnesium-iron silicate dusty tails of catastrophically evaporating rocky planets
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| Main Authors: | , , , , |
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| Format: | Preprint |
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2023
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| _version_ | 1866914634892574720 |
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| author | Estrada, Beatriz Campos Owen, James E. Jankovic, Marija R. Wilson, Anna Helling, Christiane |
| author_facet | Estrada, Beatriz Campos Owen, James E. Jankovic, Marija R. Wilson, Anna Helling, Christiane |
| contents | Catastrophically evaporating rocky planets provide a unique opportunity to study the composition of small planets. The surface composition of these planets can be constrained via modelling their comet-like tails of dust. In this work, we present a new self-consistent model of the dusty tails: we physically model the trajectory of the dust grains after they have left the gaseous outflow, including an on-the-fly calculation of the dust cloud's optical depth. We model two catastrophically evaporating planets: KIC 1255b and K2-22b. For both planets, we find the dust is likely composed of magnesium-iron silicates (olivine and pyroxene), consistent with an Earth-like composition. We constrain the initial dust grain sizes to be $\sim$ 1.25-1.75 $μ$m and the average (dusty) planetary mass-loss rate to be $\sim$ 3$M_\oplus \mathrm{Gyr^{-1}}$. Our model shows the origin of the leading tail of dust of K2-22b is likely a combination of the geometry of the outflow and a low radiation pressure force to stellar gravitational force ratio. We find the optical depth of the dust cloud to be a factor of a few in the vicinity of the planet. Our composition constraint supports the recently suggested idea that the dusty outflows of these planets go through a greenhouse effect-nuclear winter cycle, which gives origin to the observed transit depth time variability. Magnesium-iron silicates have the necessary visible-to-infrared opacity ratio to give origin to this cycle in the high mass-loss state. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2311_02477 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | On the likely magnesium-iron silicate dusty tails of catastrophically evaporating rocky planets Estrada, Beatriz Campos Owen, James E. Jankovic, Marija R. Wilson, Anna Helling, Christiane Earth and Planetary Astrophysics Catastrophically evaporating rocky planets provide a unique opportunity to study the composition of small planets. The surface composition of these planets can be constrained via modelling their comet-like tails of dust. In this work, we present a new self-consistent model of the dusty tails: we physically model the trajectory of the dust grains after they have left the gaseous outflow, including an on-the-fly calculation of the dust cloud's optical depth. We model two catastrophically evaporating planets: KIC 1255b and K2-22b. For both planets, we find the dust is likely composed of magnesium-iron silicates (olivine and pyroxene), consistent with an Earth-like composition. We constrain the initial dust grain sizes to be $\sim$ 1.25-1.75 $μ$m and the average (dusty) planetary mass-loss rate to be $\sim$ 3$M_\oplus \mathrm{Gyr^{-1}}$. Our model shows the origin of the leading tail of dust of K2-22b is likely a combination of the geometry of the outflow and a low radiation pressure force to stellar gravitational force ratio. We find the optical depth of the dust cloud to be a factor of a few in the vicinity of the planet. Our composition constraint supports the recently suggested idea that the dusty outflows of these planets go through a greenhouse effect-nuclear winter cycle, which gives origin to the observed transit depth time variability. Magnesium-iron silicates have the necessary visible-to-infrared opacity ratio to give origin to this cycle in the high mass-loss state. |
| title | On the likely magnesium-iron silicate dusty tails of catastrophically evaporating rocky planets |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2311.02477 |