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Testing the Effects of Resolution on Radial Velocities

Presentation #401.03 in the session Exoplanet Radial Velocities — iPoster Session.

Published onJun 29, 2022
Testing the Effects of Resolution on Radial Velocities

After years of steady improvement, the past decade has seen radial velocity (RV) precision stall at 1 m/s. Now, spectrographs are again pushing down toward the 10 cm/s goal to detect Earth-like extrasolar planets around Sun-like stars. One common feature to these new extreme precision radial velocity (EPRV) instruments is using higher resolution in order to resolve line shapes. With over-resolved lines, they hope to separate the line center motions of Doppler shifts from line shape changes due to stellar activity. However, there is a downside to higher resolution: fewer photons. The high resolution these instruments are using limits extreme precision to only bright stars. With the EXtreme PREcision Spectrometer (EXPRES), we are looking at systems where the previous generation of RV spectrographs have failed to detect planets. At a resolution of R=137,000, we are limited to V < ~7 if we want to achieve 20 cm/s nightly precision. The goal of my research project is to determine whether the resolution of EXPRES plays a strong role in achieving radial velocity precision. I am testing whether we can maintain our current RV precision at lower resolutions so that we could reach fainter targets. These results will inform future instrument design.

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