OSCILLATING RED GIANTS OBSERVED DURING CAMPAIGN 1 OF THE KEPLER K2 MISSION: NEW PROSPECTS FOR GALACTIC ARCHAEOLOGY

NASA’s re-purposed Kepler mission ‐ dubbed K2 ‐ has brought new scientific opportunitie s that were not anticipated for the original Kepler mission. One science goal that makes optimal use of K2’s capa bilities, in particular its 360-degree ecliptic field of view, is galacti c archaeology ‐ the study of the evolution of the Galaxy from the fossil stellar record. The thrust of this research i s to exploit high-precision, time-resolved photometry from K2 in order to detect oscillations in red giant stars. Th is asteroseismic information can provide estimates of stellar radius (hence distance), mass and age of vast numbers of stars across the Galaxy. Here we present the initial analysis of a subset of red giants, observed towards the North Galactic Gap, during the mission’s first full science campaign. We investigate the feasibility of us ing K2 data for detecting oscillations in red giants that span a range in apparent magnitude and evolutionary state (hence intrinsic luminosity). We demonstrate that oscillations are detectable for essentially all cool g iants within the logg range � 1.9‐3.2. Our detection is complete down to Kp � 14.5, which results in a seismic sample with little or no detectio n bias. This sample is ideally suited to stellar population studies that seek to investigate potential shortcomings of contemporary Galaxy models. Subject headings:stars: fundamental parameters — stars: oscillations — stars: interiors