Metallicity Distribution Function of the Eridanus II Ultra-faint Dwarf Galaxy from Hubble Space Telescope Narrowband Imaging
Author
Fu, S.W.Weisz, D.R.
Starkenburg, E.
Martin, N.
Ji, A.P.
Patel, E.
Boylan-Kolchin, M.
Côté, P.
Dolphin, A.E.
Longeard, N.
Mateo, M.L.
Sandford, N.R.
Affiliation
Steward Observatory, University of ArizonaIssue Date
2022
Metadata
Show full item recordPublisher
American Astronomical SocietyCitation
Fu, S. W., Weisz, D. R., Starkenburg, E., Martin, N., Ji, A. P., Patel, E., Boylan-Kolchin, M., Côté, P., Dolphin, A. E., Longeard, N., Mateo, M. L., & Sandford, N. R. (2022). Metallicity Distribution Function of the Eridanus II Ultra-faint Dwarf Galaxy from Hubble Space Telescope Narrowband Imaging. Astrophysical Journal.Journal
Astrophysical JournalRights
Copyright © 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
We use deep narrowband CaHK (F395N) imaging taken with the Hubble Space Telescope (HST) to construct the metallicity distribution function (MDF) of Local Group ultra-faint dwarf galaxy Eridanus II (Eri II). When combined with archival F475W and F814W data, we measure metallicities for 60 resolved red giant branch stars as faint as m F475W ∼ 24 mag, a factor of ∼4 more stars than current spectroscopic MDF determinations. We find that Eri II has a mean metallicity of [Fe/H] = -2.50 and a dispersion of, which are consistent with spectroscopic MDFs, though more precisely constrained owing to a larger sample. We identify a handful of extremely metal-poor star candidates (EMP; [Fe/H] < -3) that are marginally bright enough for spectroscopic follow-up. The MDF of Eri II appears well described by a leaky box chemical evolution model. We also compute an updated orbital history for Eri II using Gaia eDR3 proper motions, and find that it is likely on first infall into the Milky Way. Our findings suggest that Eri II underwent an evolutionary history similar to that of an isolated galaxy. Compared to MDFs for select cosmological simulations of similar mass galaxies, we find that Eri II has a lower fraction of stars with [Fe/H] < -3, though such comparisons should currently be treated with caution due to a paucity of simulations, selection effects, and known limitations of CaHK for EMPs. This study demonstrates the power of deep HST CaHK imaging for measuring the MDFs of UFDs. © 2022. The Author(s). Published by the American Astronomical Society..Note
Open access articleISSN
0004-637XVersion
Final published versionae974a485f413a2113503eed53cd6c53
10.3847/1538-4357/ac3665
Scopus Count
Collections
Except where otherwise noted, this item's license is described as Copyright © 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence.