Comparative planetology with exo-minor planets

The detection of individual exo-minor planets is now a reality [1,2]. Further, measurements of their disrupted remnants in their evolved host star atmospheres are easily detectable, allowing for dynamical and chemical comparisons with solar system asteroids and comets.

Here we focus on how solar system asteroid dynamics inform understanding of the orbital and physical history of exo-minor planets and their remnants. Because all of these detections occur around or inside of dying stars known as white dwarfs, we must determine how exo-minor planets traverse the precursor violent giant branch phases of stellar evolution. The luminosity of a giant branch star can be 10⁴ higher than the Sun’s, with significant consequences for both the YORP [3,4] and Yarkovsky [5,6] effects. We model both effects on extrasolar analogs of the Main Belt and Kuiper Belt. We demonstrate how giant branch-induced YORP fission is greatly enhanced overall but can be inhibited by internal tensile strength and can lead to binary production. We also show how pebbles, cobbles, boulders and asteroids are easily flung past major planets from the giant branch-induced Yarkovsky effect. Our investigations produce constraints on the spatial and size distributions of the resulting seas of debris.

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2. Manser et al. (2019), Science, 364, 66-69.

3. Veras, Jacobson & Gänsicke (2014), MNRAS 445, 2794-2799.

4. Veras & Scheeres (2020), MNRAS 492, 2437-2445.

5. Veras, Eggl & Gänsicke (2015), MNRAS 451, 2814-2834.

6. Veras, Higuchi & Ida (2019), MNRAS, 485, 708-724