KPF Confirms a Polar Orbit for KELT-18 b
Ryan A. Rubenzahl, Fei Dai, Samuel Halverson, Andrew W. Howard, Aaron, Householder, Benjamin Fulton, Aida Behmard, Steven R. Gibson, Arpita Roy,, Abby P. Shaum, Howard Isaacson, Max Brodheim, William Deich, Grant M. Hill,, Bradford Holden, Russ R. Laher, Kyle Lanclos

TL;DR
This study reports spectroscopic transit observations of KELT-18 b, confirming its polar orbit and suggesting high-eccentricity migration possibly caused by a binary stellar companion, contributing to understanding hot Jupiter orbital dynamics.
Contribution
First spectroscopic transit analysis of KELT-18 b confirming its polar orbit and proposing a migration mechanism involving a binary companion.
Findings
KELT-18 b has a sky projected obliquity of -94.8 degrees.
The true 3D obliquity is approximately 92 degrees.
Evidence suggests high-eccentricity migration due to Kozai-Lidov oscillations.
Abstract
We present the first spectroscopic transit results from the newly commissioned Keck Planet Finder on the Keck-I telescope at W. M. Keck Observatory. We observed a transit of KELT-18 b, an inflated ultra-hot Jupiter orbiting a hot star ( K) with a binary stellar companion. By modeling the perturbation to the measured cross correlation functions using the Reloaded Rossiter-McLaughlin technique, we derived a sky projected obliquity of deg ( deg for isotropic ). The data are consistent with an extreme stellar differential rotation (), though a more likely explanation is moderate center-to-limb variations of the emergent stellar spectrum. We see additional evidence for the latter from line widths increasing towards the limb. Using loose constraints on the stellar rotation period from observed…
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Taxonomy
TopicsParticle accelerators and beam dynamics · Particle Accelerators and Free-Electron Lasers · Magnetic confinement fusion research
