Presentation #434.02 in the session Exoplanet Radial Velocities & Transit Spectroscopy: Observations.
Statistics from transit surveys indicate that the most common type of planet is one with a radius between that of Earth and Neptune with ~30% of stars hosting one in their inner system; there is no analog of this planet type in the solar system. Radial velocity surveys have been able to characterize some of these planets, but typically only on orbits less than 40 days. We still know little about planetary system architectures at wider orbits and have yet to detect any architectures like the solar system. The 100 Earths Survey using the EXtreme PREcision Spectrometer (EXPRES) on the Lowell Discovery Telescope (LDT) is designed specifically to reveal small planets at close orbits and sub-Neptunes out to four year orbits. The program has been taking high cadence science observations since early 2019. During this time, more than one third of regularly observed systems are showing possible new planetary signals, most in multi-planet systems. I will present our latest results, focusing on one new system with two sub-Neptune mass planets.