SearcharxivSearch

arXiv subjects

Robert Royer III

Publications and source records attributed to Robert Royer III.

2 recordsLinked to original sources

Modeling Carbon-Based Planets with MAGRATHEA

A planet's interior structure not only influences its habitability, but it also provides information about the planet's formation and history. In the quest to characterize the variety of planetary discoveries, the most common practice is to rely on our understanding of the Earth's differentiated interior structure, with an iron core and silicate mantle as a starting point. However, recent work by arXiv:2408.07761 [astro-ph.EP] shows that these assumptions may not be true for all planetary systems as the composition of the condensed material can change drastically towards a carbon mantle instead of a silicate one, once the C/O ratio of the system approaches and exceeds approximately 0.9. In an effort to more fully understand the range of possible planetary bodies, we added the ability to model carbon-based mantles to our open-source planetary interior solver, MAGRATHEA. The newly added carbon mantle includes three relevant allotropes of carbon: graphite, diamond, and BC8 (body centered cubic with eight atoms per cell).

astro-ph.EP

Comparing the Architectures of Multiplanet Systems from Kepler, K2, and TESS Data

Exoplanet surveys like Kepler, TESS, and K2 have shown that planetary systems are common in our galaxy. These surveys, along with several others, have identified thousands of planetary candidates, with more than five thousand having already been confirmed. Many of these planetary systems host multiple planets. As we discover more multiplanet systems, notable trends begin to appear in the data. We use kernel density estimation (KDE) to analyze the period ratios of adjacent planet pairs in multiplanet systems in the most recent Kepler, TESS and K2 data, paying particular attention to pairs in first order mean motion resonance (MMR). We compare a recent Kepler catalog with the DR25 data release. We also compare TESS and K2 against this recently released Kepler data. To verify the significance of our findings against selection bias, we perform Monte Carlo simulations of multiplanet systems in the TESS catalog, finding an excess of planet pairs near the 2 (2:1), and 1.5 (3:2) period ratios, both exceeding the 99\% confidence interval. We also find a significant peak at the 2.19 period ratio, which exceeds the 90\% confidence interval. Using a lower limit for period ratios determined by the period of the inner planet proposed in Steffen & Farr (2013), we identify two planet pairs orbiting M dwarf stars in a very tight ratio. We also note a likely misidentified planet pair orbiting an FGK type star, which if further study proves to be true, would indicate that only planets orbiting M dwarf stars may violate this limit.

astro-ph.EP