The Stars Of The Hetdex Survey. I. Radial Velocities And Metal-Poor Stars From Low-Resolution Stellar Spectra

The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) is an unbiased, massively multiplexed spectroscopic survey, designed to measure the expansion history of the universe through low-resolution (R similar to 750) spectra of Ly alpha emitters. In its search for these galaxies, HETDEX will also observe a few times 10(5) stars. In this paper, we present the first stellar value-added catalog within the internal second data release of the HETDEX Survey (HDR2). The new catalog contains 120,571 low-resolution spectra for 98,736 unique stars between 10 < G < 22 spread across the HETDEX footprint at relatively high (b similar to 60 degrees) Galactic latitudes. With these spectra, we measure radial velocities (RVs) for similar to 42,000 unique FGK-type stars in the catalog and show that the HETDEX spectra are sufficient to constrain these RVs with a 1 sigma precision of 28.0 km s(-1) and bias of 3.5 km s(-1) with respect to the Large Sky Area Multi-Object Fibre Spectroscopic Telescope surveys and 1 sigma precision of 27.5 km s(-1) and bias of 14.0 km s(-1) compared to the Sloan Extension for Galactic Understanding and Exploration survey. Since these RVs are for faint (G >= 16) stars, they will be complementary to Gaia. Using t-Distributed Stochastic Neighbor Embedding (tSNE), we also demonstrate that the HETDEX spectra can be used to determine a star's T (eff), and log g and its [Fe/H]. With the tSNE projection of the FGK-type stars with HETDEX spectra we also identify 416 new candidate metal-poor ([Fe/H] < -1 dex) stars for future study. These encouraging results illustrate the utility of future low-resolution stellar spectroscopic surveys.