GeminiFocus June 2012 | Page 13

by Bill Blair and Frank Winkler Constraining the Optical Counterpart of a New ULX in M83 Using the Gemini Multi-Object Spectrograph at Gemini South, an international team detected the optical counterpart to an ultraluminous X-ray source first detected by Chandra in late 2010. The authors, using Gemini in classical mode, received permission to re-prioritize their existing Gemini supernova remnant observations of M83. The results, which turned out to be a successful marriage of opportunity and serendipity, are presented here. Figure 1. M83 as imaged in April 2009 with the Magellan 6.5m telescope and IMACS instrument. Red is Halpha, green is [O III] 5007, and blue is B band. 13 Using multi-wavelength observations, we, along with several collaborators, are conducting an ongoing study of the cycle of stellar birth, evolution, and death to better understand how the interplay of these processes affects the evolution of entire galaxies. A particularly fruitful element of this study entails discovering and characterizing the supernova remnant populations in nearby galaxies. Recently, our team has concentrated on the iconic, face-on spiral galaxy M83 in the constellation Hydra (see Figure 1). Fortunately, the timing of this decision to study M83 was exquisite, as it led to the discovery of a most unusual optical counterpart to a bright X-ray transient source, the brightest X-ray point event in M83 by far. The nature of this source posed a puzzle that we are beginning to under- GeminiFocus June2012