NGC 1817 IS A RICH AND RELATIVELY YOUNG (~1 BILLION YR) OPEN CLUSTER IN THE CAMPAIGN 13 FIELD. THANKS TO ITS MASS THE CLUSTER HAS A LARGE POPULATION OF EVOLVED STARS THAT WILL IMPACT A DIVERSE SET OF FIELDS IN STELLAR ASTROPHYSICS. FOR EXAMPLE COMPARED TO A CLUSTER OF SIMILAR AGE (NGC 6811) IN THE MAIN KEPLER FIELD NGC 1817 HAS A FACTOR OF 5 TIMES MORE RED CLUMP STARS. THE RED CLUMP STARS ARE BRIGHT AND COOL ENOUGH TO BE WELL SUITED FOR ASTEROSEISMIC ANALYSIS INCLUDING AGE DETERMINATIONS. SUCH A LARGE SAMPLE WILL GIVE US THE NEW OPPORTUNITY TO DO A STATISTICALLY ROBUST ASTEROSEISMIC AGE DETERMINATION FOR YOUNG CORE-HELIUM BURNING STARS. PREVIOUSLY THIS COULD ONLY BE DONE FOR OLDER CLUSTERS THAT HAVE A HEAVILY POPULATED FIRST-ASCENT GIANT BRANCH AND OUR ANALYSIS WILL PRODUCE A MUCH IMPROVED CALIBRATION OF THESE MORE MASSIVE GIANT STARS. NGC 1817 IS ALSO YOUNG ENOUGH THAT MAIN SEQUENCE STARS FALL IN THE PULSATIONAL INSTABILITY STRIP AND IT IS OLD ENOUGH THAT THE MOST EVOLVED MAIN SEQUENCE TURNOFF STARS ARE ALSO WITHIN THE STRIP. THE CLUSTER IS ALREADY KNOWN TO HAVE A LARGE POPULATION OF DELTA SCT AND GAMMA DOR PULSATING STARS THAT WILL BENEFIT FROM UNINTERRUPTED OBSERVATIONS AND THE SENSITIVITY OF THE K2 PHOTOMETRY WILL ALLOW THE DETECTION OF MANY ADDITIONAL LOW-AMPLITUDE PULSATORS THAT COULD NOT BE DETECTED FROM THE GROUND. BUT THE CLUSTER ALSO PROVIDES US WITH THE RARE OPPORTUNITY TO PRECISELY MEASURE THE MASS AND RADIUS OF A PULSATING DELTA SCT STAR AS ONE IS ALREADY KNOWN TO BE PART OF A CLUSTER ECLIPSING BINARY. THIS WOULD PROVIDE A BENCHMARK CASE FOR THE STUDY OF DELTA SCT PULSATORS AND THE EVOLVED NATURE OF THAT STAR WILL PRODUCE AN INDEPENDENT DETERMINATION OF THE CLUSTER AGE FOR COMPARISON WITH ASTEROSEISMIC RESULTS. WE PROPOSE LONG CADENCE OBSERVATIONS OF ALL OF THE KNOWN RED CLUMP STAR MEMBERS OF THE CLUSTER (FOR ASTEROSEISMOLOGY) ALL OF THE KNOWN PULSATING STARS (WITH SHORT CADENCE OBSERVATIONS OF 3 KNOWN TO HAVE HIGH FREQUENCY MODES) THE BRIGHT ECLIPSING BINARY (AGAIN WITH SHORT CADENCE) AND ALL OTHER BRIGHT MAIN SEQUENCE MEMBERS FOR THE DETECTION OF ADDITIONAL PULSATORS AND ECLIPSING SYSTEMS.
$46,687FY2017National Aeronautics and Space AdministrationNASA
San Diego State University Foundation, San Diego CA