Precursors of Supernovae from Mass Eruption: Prospects for Early Warning of Nearby Core-collapse Supernovae

Recent observations of a large fraction of Type II supernovae show traces of dense circumstellar medium (CSM) very close to the progenitor star. If this CSM is created by eruptive mass loss several months before core-collapse, the eruption itself may be visible as a precursor, helpful as an early warning of a near-future supernova. Using radiation hydrodynamical simulations based on the open-source code CHIPS, we theoretically model the emission from mass eruption of a red supergiant star. We find that for a modest mass eruption the luminosity is typically on the order of $10^{39}$ erg s$^{-1}$, can last as long as hundreds of days until the star explodes, and is mainly bright in the infrared (from -9 to -11 mag around peak). We discuss observational strategies to find these signatures from Galactic and local Type II supernovae.