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The Nature Of The Ultraluminous Oxygen‐Rich Supernova Remnant In Ngc 4449, Dan Milisavljevic, Robert A. Fesen

Dartmouth Scholarship

Optical images and spectra, both ground based and taken by Hubble Space Telescope (HST), of the young, luminous O-rich supernova remnant in the irregular galaxy NGC 4449 are presented. HST images of the remnant and its local region were obtained with the ACS/WFC using filters F435W, F555W, F814W (B, V, and I, respectively), F502N ([O III]), F658N (Hα + [N II]), F660N ([N II]), and F550M (line-free continuum). These images show an unresolved remnant (FWHM < 0.05'') located within a rich cluster of OB stars which itself is enclosed by a nearly complete interstellar shell seen best in Hα + [N II] emission approximately 8'' × 6'' (150 pc × 110 pc ) in size. The remnant and its associated OB cluster are isolated …