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arXiv · 1009.1437

The Color-Dependent Frequency of XUV Disks In Low-Mass E/S0s

Amanda J. Moffett·Sheila J. Kannappan·Andrew J. Baker·Seppo Laine
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Abstract

We identify a high frequency of Type 1 XUV disks, reflecting recent outer disk star formation, in a sample of 31 E/S0s with stellar masses primarily below M_* ~ 4 x 10^10 M_sun. Our ~40% identification rate is roughly twice the 20% fraction reported for late-type galaxies. Intriguingly, in the dwarf mass regime (below M_* ~ 5 x 10^9 M_sun) where gas fractions clearly rise, Type 1 XUV disks occur in ~70% of red-sequence E/S0s but only ~20% of blue-sequence E/S0s, a population recently linked to active disk rebuilding, especially in the dwarf regime. Our statistics are preliminary, but could indicate that for dwarf E/S0s Type 1 XUV disks are primarily related to weak or inefficient outer-disk star formation rather than to star formation capable of driving substantial disk growth. Substantial growth may instead be associated with populations that have low XUV-disk frequency, possibly explaining the similar ~20% frequencies for normal late types and low-mass blue-sequence E/S0s.

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Amanda J. Moffett, Sheila J. Kannappan, Andrew J. Baker, Seppo Laine. 2010-09-08. The Color-Dependent Frequency of XUV Disks In Low-Mass E/S0s. https://doi.org/10.1051/eas%2F1148093

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