My latest (and likely last!) paper is up on arXiv today! As the title says, it's about the "Relative Habitability of Exoplanet Systems with Two Giant Planets".
Go check it out ➡️ https://arxiv.org/abs/2205.02777
Or for a TL;DR, continue ⬇️
The basic idea is, given an exoplanet system with 2 giant planets, what can we say—from a dynamical perspective—about its ability to host a habitable Earth-like planet?
We focus here on whether the system would be stable and how the exo-Earth's eccentricity would be changed.
Unstable systems (planets ejecting or colliding): not habitable. Easy enough, except the question of whether an arbitrary 3-planet system is stable is, um, HARD. In this case, I used a bunch of different predictive techniques that have been developed by other scientists.
The question of whether an Earth-like planet is habitable and a given semi-major axis and eccentricity is likewise HARD. I (intentionally) use a very simple model here based on existing work in the field. This framework is very adaptable with other habitability models!
In general, as the exo-Earth's eccentricity increases, it gets more sunlight from its star, making it less habitable in the inner regions and more habitable in the outer regions.
For each giant planet pair, we consider 80 different locations of the exo-Earth. At each of these locations, we find the stability and habitability probabilities. Then we can integrate over the exo-Earth locations to find a relative habitability for the giant planet pair.
A couple trends we saw:
• Mass of the giant planets ↑, relative habitability ↓
• Very low relative habitability when the giant planets are in the habitable zone
• Eccentricity of the giant planets ↑, relative habitability ↓
• Secular resonances can have big effects
While in general the presence of the giant planets reduces the relative habitability compared to a system with just an exo-Earth, there are some cases where the giant planets make the system "ultra-habitable":
If this thread got you excited, you can also watch me talk about this research: https://youtu.be/0smzHsburh8?t=1847
Ty!! 😊
@norasguidetothegalaxy congrat for this ! it's really cool you can do a PhD defense _and_ a great learning video in one shot ... I enjoyed it all ;)
We looked at 147,456 different pairs of giant planets! This dataset is huge and 8-dimensional, so there's a LOT remaining to be found in it! You can play around with it yourself at: https://doi.org/10.5281/zenodo.6324216