Triggered Star Formation and the Creation of the Supergiant HI Shell in IC 2574

Abstract

Based on deep imaging from the Advanced Camera for Surveys aboard the Hubble Space Telescope, we present new evidence that stellar feedback created a ~ 1 kpc supergiant HI 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 HI and SF, we find compelling evidence that stellar feedback is responsible for creating the SGS and triggering secondary SF around its rim.

5 Pages, 4 Figures, ApJ Letter, Accepted

References in corpus (3)

• The Recent Star Formation Histories of M81 Group Dwarf Irregular Galaxies
• The LBT Panoramic View on the Recent Star-Formation Activity in IC2574
• The Formation of Constellation III in the Large Magellanic Cloud

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• Dense Molecular Clumps associated with the LMC Supergiant Shells LMC 4 \& LMC 5
• A 5deg x 5deg deep HI survey of the M81 group
• Probing star formation and feedback in dwarf galaxies. Integral field view of the blue compact galaxy Tololo 1937-423
• An Expanding Neutral Hydrogen Supershell Evacuated by Multiple Supernovae in M101