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A Comparison of Young Star Properties with Local Galactic Environment for LEGUS/LITTLE THINGS Dwarf Irregular Galaxies

Hunter, Deidre A. and Cook, David O. (2018) A Comparison of Young Star Properties with Local Galactic Environment for LEGUS/LITTLE THINGS Dwarf Irregular Galaxies. Astronomical Journal, 156 (1). Art. No. 21. ISSN 1538-3881. doi:10.3847/1538-3881/aac50e.

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We have explored the role environmental factors play in determining characteristics of young stellar objects in nearby dwarf irregular and blue compact dwarf galaxies. Star clusters are characterized by concentrations, masses, and formation rates; OB associations by mass and mass surface density; O stars by their numbers and near-ultraviolet absolute magnitudes; and H ii regions by Hα surface brightnesses. These characteristics are compared to surrounding galactic pressure, stellar mass density, H i surface density, and star formation rate (SFR) surface density. We find no trend of cluster characteristics with environmental properties, implying that larger-scale effects are more important in determining cluster characteristics or that rapid dynamical evolution erases any memory of the initial conditions. On the other hand, the most massive OB associations are found at higher pressure and H i surface density, and there is a trend of higher H ii region Hα surface brightness with higher pressure, suggesting that a higher concentration of massive stars and gas is found preferentially in regions of higher pressure. At low pressures we find massive stars but not bound clusters and OB associations. We do not find evidence for an increase of cluster formation efficiency as a function of SFR density. However, there is an increase in the ratio of the number of clusters to the number of O stars with increasing pressure, perhaps reflecting an increase in clustering properties with SFR.

Item Type:Article
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URLURL TypeDescription
Hunter, Deidre A.0000-0002-3322-9798
Cook, David O.0000-0002-6877-7655
Additional Information:© 2018 The American Astronomical Society. Received 2017 November 21; revised 2018 May 2; accepted 2018 May 13; published 2018 June 21. Results presented here are based on observations made with the NASA/ESA Hubble Space Telescope under the LEGUS survey. Support for HST program no. 13364 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. A.A. acknowledges the support of the Swedish Research Council (Vetenskapsrdet) and the Swedish National Space Board (SNSB). S.G. appreciates funding from the National Science Foundation grant AST-1461200 to Northern Arizona University for Research Experiences for Undergraduates summer internships and Drs. Kathy Eastwood and David Trilling for running the NAU REU program in 2016. S.G. also appreciates the support of the 2016 CAMPARE Scholar program and Dr. Alexander Rudolph for directing that program. Facilities: HST(ACS - , WFC3) - , VLA - , Lowell Observatory - .
Funding AgencyGrant Number
Swedish Research CouncilUNSPECIFIED
Swedish National Space Board (SNSB)UNSPECIFIED
Northern Arizona UniversityUNSPECIFIED
Subject Keywords:galaxies: dwarf – galaxies: individual (DDO 50, DDO 53, DDO 63, NGC 3738, Haro 29)
Issue or Number:1
Record Number:CaltechAUTHORS:20180620-135324765
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Official Citation:Deidre A. Hunter et al 2018 AJ 156 21
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87269
Deposited By: Tony Diaz
Deposited On:20 Jun 2018 21:14
Last Modified:15 Nov 2021 20:46

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