Collaborative Research: Speckle Surveys of Nearby Stars

About This Grant

A research collaboration between Georgia State University, Bridgewater State University and Southern Connecticut State University will observe a sample of nearly 5000 stars across the entire sky using a technique called speckle imaging. The observations will focus on two volume-limited, volume-complete samples of K dwarf stars within 40 parsecs of the Sun and M dwarf stars within 20 parsecs, our Sun’s nearest stellar neighbors. The choice of nearby stars will enable imaging of their stellar environments down to separations smaller than the distance of Mercury to the Sun. This will allow them to discover how unusual our Sun is in its stellar solitude and provide a list of stars around which other solar systems might be found because they lack close companion stars. The project is student-intensive, with graduate and undergraduate students carrying out the work at three universities, including an outreach effort entitled “Why Resolution Matters.” The project provides opportunities to gain expertise in (1) science — astronomy and physics, (2) mathematics — intensive data acquisition and reduction, with statistical treatments of results involving large databases, and (3) engineering — using some of the U.S.’s premier telescopes equipped with state-of-the-art instruments. This work will allow the researchers to detect stellar companions and provide benchmark measurements of their (1) luminosity function, (2) mass function, (3) multiplicity rates, (4) masses, (5) mass-luminosity relations, and (6) orbital architectures. The survey will comprise legacy samples that will continue to be the subject of ground-based and spaced-base efforts. The speckle imaging surveys will be carried out primarily at the APO 3.5m telescope with DSSI in the northern hemisphere and the SOAR 4.1m telescope with HRCam+SAM in the south. The speckle surveys are particularly relevant to exoplanet work, because they sample scales of 0.1–100 AU around the stars, similar to where planets are found in our Solar System. The results will be combined with a sweep of wide-field companions found in Gaia for larger separations and companions at small separations found via previous high-resolution efforts and in radial velocity surveys that are sensitive to lower-mass objects. The orbital architectures of companions to K and M dwarfs will be compared directly to planets reported to be orbiting stars in the same samples. A third sample of AFG stars will serve as a comparison to higher mass stars, with a nod toward lower metallicities to investigate dependences on how stars form in different historical environments. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.