Program: GN-2021B-Q-309

RR Lyrae stars are a staple of our understanding of old stellar populations, and yet, one of its most fundamental parameters, mass, has been only predicted from stellar evolution models, but never measured. This is because of the incredible lack of detections of RRL in binary systems. We propose speckle observations of 53 well-characterized RRL in the solar neighborhood. Speckle observations with 'Alopeke and Zorro, sensitive to companions down to ~7 magnitudes fainter than the primary RRL, will provide strong constraints on the binarity of these systems, and a first step into measuring their masses. Since only one RRL has been proved to reside in a binary system so far, any new detections will have a key value in moving forward the field.