2015/12/31 by Michitoshi Yoshida, Masafumi Yagi, Youichi Ohyama +4 · 3 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Emission nebula #Galaxies: Formation, Evolution, Phenomena #Galaxy #Luminosity #Nebula #Orion Nebula #Protoplanetary nebula #Reflection nebula #Stars #Surface brightness #astro-ph.GA
paper · pdf · doi:10.3847/0004-637x/820/1/48
17 pages, 12 figures. Accepted by ApJ
arxiv created 2015/12/31 · openalex publication_date 2016/03/17 · arxiv updated 2016/03/23 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
ABSTRACT We revealed the detailed structure of a vastly extended H α -emitting nebula (“H α nebula”) surrounding the starburst/merging galaxy NGC 6240 by deep narrow-band imaging observations with the Subaru Suprime-Cam. The extent of the nebula is ∼90 kpc in diameter and the total H α luminosity amounts to L H α ≈ 1.6 × 10 42 erg s −1 . The volume filling factor and the mass of the warm ionized gas are ∼10 −4 –10 −5 and ∼5 × 10 8 M ⊙ , respectively. The nebula has a complicated structure, which includes numerous filaments, loops, bubbles, and knots. We found that there is a tight spatial correlation between the H α nebula and the extended soft-X-ray-emitting gas, both in large and small scales. The overall morphology of the nebula is dominated by filamentary structures radially extending from the center of the galaxy. A large-scale bipolar bubble extends along the minor axis of the main stellar disk. The morphology strongly suggests that the nebula was formed by intense outflows—superwinds—driven by starbursts. We also found three bright knots embedded in a looped filament of ionized gas that show head-tail morphologies in both emission-line and continuum, suggesting close interactions between the outflows and star-forming regions. Based on the morphology and surface brightness distribution of the H α nebula, we propose the scenario that three major episodes of starburst/superwind activities, which were initiated ∼10 2 Myr ago, formed the extended ionized gas nebula of NGC 6240.