Daniel R. Weisz et al 2009 ApJ 691 L59 doi:10.1088/0004-637X/691/1/L59
Daniel R. Weisz1, Evan D. Skillman1, John M. Cannon2, Fabian Walter3, Elias Brinks4, Jürgen Ott5,6,8 and Andrew E. Dolphin7
Show affiliationsBased on deep imaging from the Advanced Camera for Surveys aboard the Hubble Space Telescope (HST), we present new evidence that stellar feedback created a ~1 kpc supergiant H I shell (SGS) and triggered star formation (SF) around its rim in the M81 Group dwarf irregular galaxy IC 2574. Using photometry of the resolved stars from the HST images, we measure the star formation history of a region including the SGS, focusing on the past 500 Myr, and employ the unique properties of blue helium-burning stars to create a movie of SF in the SGS. We find two significant episodes of SF inside the SGS from 200-300 Myr and ~25 Myr ago. Comparing the timing of the SF events to the dynamic age of the SGS and the energetics from the H I and SF, we find compelling evidence that stellar feedback is responsible for creating the SGS and triggering secondary SF around its rim.
galaxies: dwarf; galaxies: individual (IC 2574); galaxies: irregular; galaxies: ISM; stars: formation
98.58.-w Interstellar medium (ISM) and nebulae in external galaxies
98.52.Wz Dwarf galaxies (elliptical, irregular, and spheroidal)
95.55.-n Astronomical and space-research instrumentation
98.62.Ai Origin, formation, evolution, age, and star formation
95.80.+p Astronomical catalogs, atlases, sky surveys, databases, retrieval systems, archives, etc.
Issue 1 (2009 January 20)
Received 2008 November 17, accepted for publication 2008 December 10
Published 2009 January 7
Daniel R. Weisz et al 2009 ApJ 691 L59
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John M. Cannon et al 2005 ApJ 630 L37
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