Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the MBM12 Young Association   I present a comprehensive study of the MBM12 young association (MBM12A). By
combining infrared (IR) photometry from the Two-Micron All-Sky Survey (2MASS)
survey with new optical imaging and spectroscopy, I have performed a census of
the MBM12A membership that is complete to 0.03 Msun (H~15) for a 1.75deg X
1.4deg field encompassing the MBM12 cloud. I find five new members with masses
of 0.1-0.4 Msun and a few additional candidates that have not been observed
spectroscopically. From an analysis of optical and IR photometry for stars in
the direction of MBM12, I identify M dwarfs in the foreground and background of
the cloud. By comparing the magnitudes of these stars to those of local field
dwarfs, I arrive at a distance modulus 7.2+/-0.5 (275 pc) to the MBM12 cloud;
it is not the nearest molecular cloud and is not inside the local bubble of hot
ionized gas as had been implied by previous distance estimates of 50-100 pc. I
have also used Li strengths and H-R diagrams to constrain the absolute and
relative ages of MBM12A and other young populations; these data indicate ages
of 2 +3/-1 Myr for MBM12A and 10 Myr for the TW Hya and Eta Cha associations.
MBM12A may be a slightly evolved version of the aggregates of young stars
within the Taurus dark clouds (~1 Myr) near the age of the IC 348 cluster (~2
Myr).

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The categories of this paper are: hep-lat
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The categories of this paper are: chao-dyn
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ex
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The categories of this paper are: math-ph
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The categories of this paper are: q-bio
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The categories of this paper are: patt-sol
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The categories of this paper are: atom-ph
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The categories of this paper are: math
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The categories of this paper are: cs
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The categories of this paper are: cond-mat
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-th
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The categories of this paper are: nlin
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The categories of this paper are: dg-ga