Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The mid-life crisis of the Milky Way and M31   Upcoming next generation galactic surveys, such as GAIA and HERMES, will
deliver unprecedented detail about the structure and make-up of our Galaxy, the
Milky Way, and promise to radically improve our understanding of it. However,
to benefit our broader knowledge of galaxy formation and evolution we first
need to quantify how typical the Galaxy is with respect to other galaxies of
its type. Through modeling and comparison with a large sample of galaxies drawn
from the Sloan Digital Sky Survey and Galaxy Zoo, we provide tentative yet
tantalizing evidence to show that both the Milky Way and nearby M31 are
undergoing a critical transformation of their global properties. Both appear to
possess attributes that are consistent with galaxies midway between the
distinct blue and red bimodal color populations. In extragalactic surveys, such
`green valley' galaxies are transition objects whose star formation typically
will have all but extinguished in less than ~5 Gyrs. This finding reveals the
possible future of our own galactic home, and opens a new window of opportunity
to study such galactic transformations up close.

34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom