Journal
ASTRONOMICAL JOURNAL
Volume 154, Issue 5, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.3847/1538-3881/aa8c04
Keywords
planet-star interactions; planets and satellites: dynamical evolution and stability; planets and satellites: formation
Categories
Funding
- NASA ATP [NNX13AH56G]
- University of Chicago College Research Fellows Fund award
Ask authors/readers for more resources
In the high-eccentricity migration (HEM) scenario, close-in planets reach the vicinity of the central star on high-eccentricity orbits that become circularized-with a concomitant decrease in the semimajor axis-through a tidal interaction with the star. Giant planets that arrive with periastron distances that are smaller than the Roche limit a(R) lose their gaseous envelopes, resulting in an inner edge to the surviving planets' distribution. The observational evidence for this effect, while extensive, is nonetheless somewhat ambiguous because of the effect of tidal orbital decay. Here, we consider another key prediction of the HEM scenario-the existence of a spatial eccentricity gradient near the location where the circularization time becomes comparable to the planet's age for typical parameters. Previous studies have already found evidence for this gradient and demonstrated that its properties are consistent with the circularization process being dominated by tidal dissipation in the planet (encapsulated by the tidal quality factor Q(p)(')). Our work extends these treatments by constructing explicit model distributions for comparison with the data and by carrying out backward-in-time integrations using observed system parameters. We show that circularization generally occurs outside the distribution's inner edge (which defines the boundary of the so-called sub-Jovian desert) and that typically Q(p)(') approximate to 10(6) in the circularization zone (to within a factor of 3). We also find tentative evidence for an eccentricity gradient in lower-mass planets, indicating that formation through HEM may be relevant down to Neptune scales.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available