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arXiv · 0712.1044

Finding Extreme Subdwarfs

J. L. Marshall
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Abstract

I develop a new technique to identify M-type extreme subdwarfs (esdMs) and demonstrate that it is substantially more efficient than previous methods. I begin by obtaining spectroscopy and improved photometry of a sample of 54 late-type halo candidates using the rNLTT reduced proper motion (RPM) diagram. From spectroscopy, I find that four of these are esdMs, three of which were previously unknown. From the improved photometry, I show that all four lie in a narrow RPM corridor that contains only 4 non-esdMs. Hence, with good photometry (i.e., without spectroscopy), it appears possible to select esdM candidates with a 50% esdM yield. This is more than an order of magnitude more efficient than previous methods.

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J. L. Marshall. 2007-12-06. Finding Extreme Subdwarfs. https://doi.org/10.1088/0004-6256%2F135%2F3%2F1000

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