Reinvestigation of the Multi-Epoch Direct Detections of HD 88133 b and Upsilon Andromedae b

TL;DR

This paper reevaluates previous direct detections of exoplanets HD 88133 b and ups And b, showing that earlier claims were unlikely given the data, and emphasizes the importance of simulations and careful analysis in high-resolution spectroscopy.

Contribution

It demonstrates how simulations can assess the detectability of exoplanets in high-resolution spectra and clarifies the conditions needed for successful detection.

Findings

Previous detections were unlikely given the data and stellar properties.

Simulations show upgraded instruments and specific observing strategies improve detection prospects.

More epochs are needed for reliable detection of certain exoplanets.

Abstract

We reanalyze the multi-epoch direct detections of HD 88133 b and ups And b that were published in Piskorz et al. 2016 and Piskorz et al. 2017, respectively. Using simulations to attempt to reproduce the detections, we find that with the 6 and 7 $L$ band Keck/NIRSPEC epochs analyzed in the original works, the planets would not have been detectable unless they had unreasonably large radii. HD88133 and ups And both have fairly large stellar radii, which contributed to the difficulty in detecting the planets. We take this opportunity to consider how these planets may have been detectable with the small number of epochs originally presented by running simulations both with the upgraded NIRSPEC instrument and with near-zero primary velocities, as recommended by Buzard et al. 2021. While 7 $L$ band NIRSPEC2.0 epochs with near-zero primary velocities would have allowed a strong ($10.8\sigma$) detection of ups And b, many more than 6 $L$ band epochs would have been required for a strong detection of HD88133b, which could be due in part to both this system's large stellar radius and low stellar temperature. This work stresses the importance of careful analytic procedures and the usefulness of simulations in understanding the expected sensitivity of high-resolution spectroscopic data.