TY - JOUR
T1 - DEEP IMAGING of ERIDANUS II and ITS LONE STAR CLUSTER
AU - Crnojević, D.
AU - Sand, D. J.
AU - Zaritsky, D.
AU - Spekkens, K.
AU - Willman, B.
AU - Hargis, J. R.
N1 - Funding Information:
We thank the anonymous referee for their thoughtful suggestions and Tom Maccarone for useful discussions. D.J. S. acknowledges financial support from NSF grant AST-1412504; D.Z. acknowledges support from NSF AST-1311326; B.W. acknowledges support from NSF AST-1151462.
Publisher Copyright:
© 2016. The American Astronomical Society. All rights reserved..
PY - 2016/6/10
Y1 - 2016/6/10
N2 - We present deep imaging of the most distant dwarf discovered by the Dark Energy Survey, Eridanus II (Eri II). Our Magellan/Megacam stellar photometry reaches ∼3 mag deeper than previous work and allows us to confirm the presence of a stellar cluster whose position is consistent with Eri II's center. This makes Eri II, at Mv = -7.1, the least luminous galaxy known to host a (possibly central) cluster. The cluster is partially resolved, and at it accounts for ∼4% of Eri II's luminosity. We derive updated structural parameters for Eri II, which has a half-light radius of ∼280 pc and is elongated ( ∼ 0.48) at a measured distance of D ∼ 370 kpc. The color-magnitude diagram displays a blue, extended horizontal branch, as well as a less populated red horizontal branch. A central concentration of stars brighter than the old main-sequence turnoff hints at a possible intermediate-age (∼3 Gyr) population; alternatively, these sources could be blue straggler stars. A deep Green Bank Telescope observation of Eri II reveals no associated atomic gas.
AB - We present deep imaging of the most distant dwarf discovered by the Dark Energy Survey, Eridanus II (Eri II). Our Magellan/Megacam stellar photometry reaches ∼3 mag deeper than previous work and allows us to confirm the presence of a stellar cluster whose position is consistent with Eri II's center. This makes Eri II, at Mv = -7.1, the least luminous galaxy known to host a (possibly central) cluster. The cluster is partially resolved, and at it accounts for ∼4% of Eri II's luminosity. We derive updated structural parameters for Eri II, which has a half-light radius of ∼280 pc and is elongated ( ∼ 0.48) at a measured distance of D ∼ 370 kpc. The color-magnitude diagram displays a blue, extended horizontal branch, as well as a less populated red horizontal branch. A central concentration of stars brighter than the old main-sequence turnoff hints at a possible intermediate-age (∼3 Gyr) population; alternatively, these sources could be blue straggler stars. A deep Green Bank Telescope observation of Eri II reveals no associated atomic gas.
KW - galaxies: dwarf
KW - galaxies: individual (Eridanus II)
KW - galaxies: photometry
KW - galaxies: stellar content
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U2 - 10.3847/2041-8205/824/1/L14
DO - 10.3847/2041-8205/824/1/L14
M3 - Article
AN - SCOPUS:84976376870
SN - 2041-8205
VL - 824
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L14
ER -