ATLAS — A Trail to Life Around Stars: A Survey of Planets Orbiting M Dwarfs within 25 Parsecs

M dwarfs are notoriously the most common type of stars in the Milky Way, and undoubtedly in other galaxies as well. They are cooler and dimmer than more massive stars, and consume their hydrogen slowly over extraordinarily long periods of time, creating enduring stable environments in which life might originate and thrive. Pragmatically, M dwarfs are excellent candidates to search for other worlds because their small stellar radii and masses permit the detection of Earth-size planets. An M dwarf with minimal stellar activity is an ideal host for an exoplanet, in particular because the lack of stellar flaring would allow an atmosphere to be preserved. The goal of this project, known as ATLAS, is to follow the trail to life by revealing the ‘quiet’ nearby M dwarfs that have planets. We expect that variability in excess of 1% at optical wavelengths would lead to elevated variability at higher energies, thereby making such stars less than optimal for habitability. REsearch Consortium On Nearby Stars (RECONS) efforts over the past two decades provide unique insight into the long-term variability of nearby star systems and their environments. At the CTIO/SMARTS 0.9m telescope we are currently observing 456 M stars of the nearest M dwarfs, among which are 30 systems with 61 reported exoplanets that already have an average 12 years of photometric data. An additional 15 systems with 21 exoplanets are being added to the program. Here we explore the data already in-hand to evaluate the environments experienced by many of the nearest exoplanets, as a step along the trail to finding life. This work has been supported by NSF grants AST-0507711, AST-0908402, AST-1109445, AST-141206, and AST-1715551 and the SMARTS Consortium.