A deep search for Galactic Wolf-Rayets: Probes of massive star formation and the interstellar medium

摘要

The research involved a deep survey of the Southern Milky Way for distant Wolf-Rayet stars. These massive objects are probable supernova progenitors. Using direct narrowband and broadband UK Schmidt plates, we have imaged over 100 square degrees in the galactic plane. The photographic plates were digitized, and object detection algorithms were run to find all stars. Typically, one million stars appear on each plate, and 100 of these appear brighter in the He-II 4686 image. Spectra are obtained of all candidates to confirm if they are really WR stars. Most candidates turn out to be variable stars changing brightness significantly between plates. Twenty-three WR stars have been detected, doubling the number known in the area previously covered. A significant gradient in the ratio of carbon-rich to nitrogen-rich stars is apparent, with WC stars located preferentially towards the galactic center, as theory predicts.