Document Type

Article

Publication Date

4-10-2008

Publication Title

The Astrophysical Journal

Department

Department of Physics and Astronomy

Abstract

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 from two large nearby H II regions. The ACS [O III] image shows the remnant may be partially surrounded by a clumpy ring of emission approximately 1'' (~20 pc) in diameter. Recent ground-based spectra of the remnant reveal (1) the emergence of broad, blueshifted emission lines of [S II] λλ6716, 6731, [Ar III] λ7136, and [Ca II] λλ7291, 7324 which were not observed in spectra taken in 1978-1980; (2) faint emission at 6540-6605 Å centered about Hα and [N II] λλ6548, 6583 with an expansion velocity of 500 ± 100 km s−1; and (3) excess emission around 4600-4700 Å suggestive of a Wolf-Rayet population in the remnant's star cluster. We use these new data to re-interpret the origin of the remnant's prolonged and bright luminosity and propose that the remnant is strongly interacting with dense, circumstellar wind loss material from a 20 M☉ progenitor star.

DOI

10.1086/528929

Original Citation

Dan Milisavljevic and Robert A. Fesen 2008 ApJ 677 306

Download

Share

COinS