March 18, 2022

The ExoExplorer Science Series presents talks by cohort members Romy Rodriguez Martinez (Ohio State) & Eckhart Spalding (Notre Dame) on March 18, 2022, from 11 AM - 12 PM Pacific / 2 PM - 3 PM Eastern. Connection information is below.

Speaker: Romy Rodriguez Martinez (Ohio State)

Title: A reanalysis of the composition of K2-106b, an ultra-short period super-Mercury candidate

Abstract: Super-Mercuries are a class of exoplanets with radii less than ~1.5 Re, high bulk densities and relatively large core-mass fractions (CMFs). The study of super-Mercuries will shed light on the composition of low-mass, terrestrial exoplanets as well as on the mechanisms that lead to the formation of iron-rich planets. However, only a few exoplanets have been confirmed as super-Mercuries, in part because of the challenges of obtaining the precise stellar and planetary parameters required to confirm them. I present a reanalysis of the K2-106 system, which contains an ultra-short period, super-Mercury candidate with a density from the literature of 13.1 (+5.4 -3.6) g/cc, approximately twice the density of Earth. We globally model extant photometry and radial velocity of the system and derive a planetary mass and radius that leads to a considerably lower density than previously reported. We derive the host star’s Fe, Mg and Si abundances and combine them with planet interior models to infer the CMF and interior composition of K2-106b. Using a statistical framework, we compared the planet’s CMF as expected from the planet’s density and the CMF as expected from the host star. Our analysis suggests that, although K2-106b has a high density and CMF, it is statistically unlikely to be a super-Mercury.

Speaker: Eckhart Spalding (Notre Dame)

Title: The quest for exoplanet direct imaging with ELT apertures: A hunt for companions with the Large Binocular Telescope

Abstract: Direct imaging of exoplanets is a promising route to finding and characterizing exoplanets in the thermal infrared. Currently the technique is most sensitive to massive, young planets on wide orbits. Innovative observing techniques are necessary to probe smaller angles from host stars, or search for older or lower-mass planets. The Large Binocular Telescope (LBT) is in a unique position to push these frontiers in preparation for the era of 30-m-class extremely large telescopes. When light is combined coherently in a "Fizeau" mode between the LBT's twin 8.4-m sub-telescopes, the facility effectively becomes a masked 22.7-m telescope. I will present an observation of the nearby star Altair in this mode, which represents the first LBT Fizeau dataset with a degree of automated phase control. These data constrain the existence of companions of 1.3 M⊙ down to an inner angle of ≈0.15", closer than any previously published direct imaging of Altair. I outline ways forward, in terms of software and physical upgrades, and post-processing with longer integration times.

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