Radial Star Formation Histories in 32 Nearby Galaxies

Journal Article · Fri May 01 04:00:00 EDT 2020 · The Astronomical Journal (Online)

DOI:https://doi.org/10.3847/1538-3881/AB7EB2· OSTI ID:23013184

Dale, Daniel A.; Lee, Nathan J.; Alexander Slane, F.; Jensen, Emily I.; Sutter, Jessica S.; Turner, Jordan A.; Kobulnicky, Henry A. ^[1]; Anderson, Kristin R. ^[2]; Bran, Louis M. ^[3]; Cox, Isaiah S. ^[4]; Drake, Carolyn L. ^[5]; Pilawa, Jacob D. ^[6]; Soto, Susana ^[7]

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1. Department of Physics & Astronomy, University of Wyoming, Laramie WY (United States)
2. Department of Physics & Astronomy, California State University, Long Beach, CA (United States)
3. Department of Mathematics & Applied Physics, California State University Channel Islands, Camarillo, CA (United States)
4. Department of Physics & Astronomy, East Tennessee State University, Johnson City, TN (United States)
5. Department of Astronomy, Whitman College, Walla Walla, WA (United States)
6. Department of Physics & Astronomy, Colgate University, Hamilton, NY (United States)
7. Department of Physics & Astronomy, University of California, Irvine, CA (United States)

The spatially resolved star formation histories are studied for 32 normal star-forming galaxies drawn from the Spitzer Extended Disk Galaxy Exploration Science survey. At surface brightness sensitivities fainter than 28 mag arcsec{sup −2}, the new optical photometry is deep enough to complement archival ultraviolet and infrared imaging and to explore the properties of the emission well beyond the traditional optical extents of these nearby galaxies. Fits to the spectral energy distributions using a delayed star formation history model indicate a subtle but interesting average radial trend for the spiral galaxies: the inner stellar systems decrease in age with increasing radius, consistent with inside-out disk formation, but the trend reverses in the outermost regions with the stellar age nearly as old as the innermost stars. These results suggest an old stellar outer disk population formed through radial migration and/or the cumulative history of minor mergers and accretions of satellite dwarf galaxies. The subset of S0 galaxies studied here show the opposite trend compared to what is inferred for spirals: characteristic stellar ages that are increasingly older with radius for the inner portions of the galaxies, and increasingly younger stellar ages for the outer portions. This result suggests that either S0 galaxies are not well modeled by a delayed-τ model, and/or that S0 galaxies have a more complicated formation history than spiral galaxies.

• OSTI ID: 23013184
• Journal Information: The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 5 Vol. 159; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BRIGHTNESS
GALAXIES
PHOTOMETRY
SENSITIVITY
STAR EVOLUTION
ULTRAVIOLET RADIATION