The Void in the Sculptor Group Spiral Galaxy NGC 247

Abstract

The dwarf galaxy NGC 247, located in the Sculptor Filament, displays an apparent void on the north side of its spiral disk. The existence of the void in the disk of this dwarf galaxy has been known for some time, but the exact nature and cause of this strange feature has remained unclear. We investigate the properties of the void in the disk of NGC 247 using photometry of archival Hubble Space Telescope data to analyze the stars in and around this region. Based on a grid of isochrones from log(t)=6.8 to log(t)=10.0, we assign ages using nearest-neighbor interpolation. Examination of the spatial variation of these ages across the galaxy reveals an age difference between stars located inside the void region and stars located outside this region. We speculate that the void in NGC 247's stellar disk may be due to a recent interaction with a nearly dark sub-halo that collided with the disk and could account for the long-lived nature of the void.

11 pages, 10 figures, 3 tables. Accepted 2014 June 25. Received 2014 June 2; in original form 2014 March 25. MN-14-0765-MJ

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Cited by in corpus (4)

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• New luminous blue variable candidates in the NGC 247 galaxy
• The Lop-sided Spiral Galaxy NGC 247: Clues to a Possible Interaction with NGC 253
• Low-density star cluster formation: discovery of a young faint fuzzy on the outskirts of the low-mass spiral galaxy NGC 247