MOPSS I: Flat Optical Spectra for the Hot Jupiters WASP-4 b and WASP-52b

TL;DR

This paper introduces MOPSS, a survey creating uniform optical spectra of exoplanets, presenting flat spectra for two hot planets indicating aerosols, and discussing implications for future observations including JWST.

Contribution

First uniform optical transmission spectra database for exoplanets, with initial results showing featureless spectra and aerosol presence, aiding comparative studies and future telescope planning.

Findings

Both planets show flat, featureless spectra indicating aerosols.

Cloud decks are located no lower than 10$^{-4}$ bar.

Star spots can influence transmission spectra and limb darkening.

Abstract

We present the first results from MOPSS, The Michigan Optical Planetary Spectra Survey, aimed at creating a database of optical planetary transmission spectra all observed, reduced, and analyzed with a uniform method for the benefit of enabling comparative exoplanet studies. We discuss our methods, and present results for our first two targets observed with the Magellan Baade 6.5m telescope, one transit of the Hot Jupiter WASP-4b and two transits of the Hot Saturn WASP-52b. Both targets present flat, featureless spectra, corresponding to the presence of aerosols. We find that the cloud decks must begin no lower than 10$^{-4}$ bar for both planets. For WASP-52b, we also consider the effects of star spots on the transmission spectrum, including unocculted spots and spots on the stellar limb influencing the light curve limb darkening parameters. We discuss the usefulness of this program in the coming James Webb Space Telescope era.