COS Legacy Archive Spectroscopic SurveY ("CLASSY")

The COS Legacy Spectroscopic SurveY (CLASSY) is a treasury survey that builds on the Hubble Space Telescope (HST) archive to construct the first high-quality, high-resolution far-ultraviolet (far-UV) spectral database of 45 nearby star-forming galaxies. The survey combines 177 orbits of archival observations with 135 new orbits (312 total orbits) of HST observations, or more than 600 total spectral images taken with the Cosmic Origins Spectrograph (COS). The CLASSY Treasury sample contains 45 star-forming galaxies selected to span similar properties as seen at high redshift, with a large range of masses, metallicities, ionization parameters, and densities, but enhanced star formation rates. The CLASSY spectral atlas contains a suite of emission and absorption features that enable investigations of the massive stellar population properties, the physical properties of large-scale outflows that regulate star formation, and the chemical abundance patterns of the gas and stars. The main objective of CLASSY is to use FUV spectra to unify stellar and gas-phase physics, allowing a holistic understanding of massive stars as the drivers of the gaseous evolution of star-forming galaxies.