Planetary radii and orbital periods for planets (black circles) and planetary candidates (red circles) discovered by the Kepler mission. The dashed curves shows how close different planets can get to their host stars before they would be tidally disrupted. Taken from Jackson et al. (2016).
Exciting news – just today, my research group had another paper accepted for publication, so we’ve added one more tiny brick to the edifice of human knowledge.
This paper explored tidal disruption of gaseous exoplanets. Over the last few decades, astronomers have discovered thousands of planets outside of our solar system, so-called “exoplanets”.
Most of the planets do not resemble planets in our solar system, and owing to biases in the way we find the planets, many of them are big, gas balls like Jupiter but orbiting much closer to their host stars than planets in our solar system – these planets are called “hot Jupiters“. The figure at left shows how close some of these planets are to their host stars.
Many of these hot Jupiters are doomed to spiral in toward their host stars, and when they get too close, the star’s gravity can rip them apart in a process called “tidal disruption“.
In our recent paper, we studied that process to try to understand how close a planet can get before it’s ripped apart and what might happen as it’s being ripped apart. The upshot of our study is that planets might get ripped apart a little farther from their stars than is often assumed BUT that ripping-apart process might proceed fairly slowly, over billions of years.
Final day of the IAU meeting general assembly found me in talks about transit-timing variations, tidal interactions, and planets in binary star systems.
The first session focused on the impressive results from transit-timing variation (TTV) studies. Since detecting and modeling TTVs is very data-intensive, the talks explored the data science aspects of TTV analysis. Ben Montet‘s talk, for example, looked at how hard it can be to detect transits in the first place, much less measure their period variations. To estimate uncertainties on their variations, he advocated using importance sampling and generating thoroughly explored prior distributions.
The next session looked at tidal interactions and planets in binary star systems. Smadar Naoz talked about her work on Kozai oscillations and how she showed that Kozai had made some fairly specific assumptions that limited his famous dynamical analysis in important ways. Her improved analysis shows that, contrary to the original results, the Kozai mechanism can actually produce planets on retrograde orbits and so can help explain the growing number of such retrograde planets.
I also spoke in the second session about Roche lobe overflow in short-period gaseous exoplanets, and I’ve posted my presentation below.
So, all in all, a really brilliant conferences in an inspiring locale. Mahalo, Hawaii.
Tidal Decay and Disruption of Gaseous Exoplanets
Day 1 of International Astronomical Union’s joint meeting with the American Astronomical Society in steamy Honolulu.
I attended the morning session on Dynamical astronomy in the solar system and beyond and saw some amazing talks on developments in computing planetary and satellite ephemerides, the modern day equivalent of Laplace’s Demon. These sophisticated computer programs are able to predict planetary positions to breath-taking accuracy and are sensitive enough to require including the gravitational influence of the 30 largest Trans-Neptunian Objects.
Coffee break then a late morning session on protoplanetary disks, where I learned about recent developments in the theory of disks and saw more of the beautiful disk images produced by the ALMA array.
Then a lunch session on Inclusive Astronomy led by Prof. Meredith Hughes discussing things we, as a community, can do to welcome and help people who face unusual challenges to entering and staying in the field. For example, we were advised to use sans serif fonts in our presentations because they are easier to read for those with dyslexia.
I skipped the plenary talk to attend the poster session (which were inexplicably scheduled on top of one another). I chatted with Erika Nesvold of SMACK fame about her recent result, explaining observations of an asymmetric distribution of CO in the Beta Pictoris protoplanetary disk via enhanced collisions among dust grains in the disk.
On Friday, everyone in our research group gave a little update on what they’ve been up to.
Liz and Jennifer talked about Parmentier et al.’s (2013) paper on the meteorology of hot Jupiters and how condensates are transported throughout these dynamic atmospheres.
Emily talked about working through the first few chapters of Murray & Dermott’s classic Solar System Dynamics. She will eventually study the orbital dynamics of systems of exoplanets very close to their host stars.
Brenton discussed his reading of Balme & Greeley (2006) on dust devils in preparation for working with me on terrestrial and Martian dust devils. A very exciting possibility, Brenton and the rest of the group said dust devils are common just south of Boise. Good chance we can do some in-situ monitoring locally.
Nathan spoke briefly about looking for more very short-period planets using data from the Kepler and K2 missions.
In attendance were Liz Kandziolka, Jennifer Briggs, Emily Jensen, Brenton Peck, Nathan Grigsby, Trent Garrett, and Tiffany Watkins.