Star Formation Histories of the LEGUS Spiral Galaxies. I. The flocculent spiral NGC 7793

Abstract

We present a detailed study of the flocculent spiral galaxy NGC 7793, part of the Sculptor group. By analyzing the resolved stellar populations of the galaxy, located at a distance of ~3.7 Mpc, we infer for the first time its radial star formation history (SFH) from Hubble Space Telescope photometry, thanks to both archival and new data from the Legacy ExtraGalactic UV Survey. We determine an average star formation rate (SFR) for the galaxy portion covered by our F555W and F814W data of 0.23 +- 0.02 Msun/yr over the whole Hubble time, corresponding to a total stellar mass of 3.09 +- 0.33 x 10^9 Msun in agreement with previous determinations. Thanks to the new data extending to the F336W band, we are able to analyze the youngest stellar populations with a higher time resolution. Most importantly, we recover the resolved SFH in different radial regions of the galaxy; this shows an indication of a growing trend of the present-to-past SFR ratio, increasing from internal to more external regions, supporting previous findings of the inside-out growth of the galaxy.

15 pages, 14 figures, accepted for publication in ApJ

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• Candidate LBV stars in galaxy NGC 7793 found via HST photometry + MUSE spectroscopy
• Tracing young star-forming clumps in the nearby flocculent spiral galaxy NGC 7793 with UVIT imaging
• The Age-Dependence of Mid-Infrared Emission Around Young Star Clusters
• The SAMI Galaxy Survey: Using concentrated star-formation and stellar population ages to understand environmental quenching
• A Multi-Wavelength Study of Star Formation in 15 Local Star-Forming Galaxies
• The Local Ultraviolet to Infrared Treasury I. Survey Overview of the Broadband Imaging
• Resolved nuclear kinematics link the formation and growth of nuclear star clusters with the evolution of their early and late-type hosts