Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lessons from Comparisons between the Nuclear Region of the Milky Way &
  Those in Nearby Spirals   The Milky Way appears is a typical barred spiral, and comparisons can be made
between its nuclear region and those of structurally similar nearby spirals.
Maffei 2, M83, IC 342 and NGC 253 are nearby systems whose nuclear region
properties contrast with those of the Milky Way. Stellar masses derived from
NIR photometery, molecular gas masses and star formation rates allow us to
assess the evolutionary states of this set of nuclear regions. These data
suggest similarities between nuclear regions in terms of their stellar content
while highlighting significant differences in current star formation rates. In
particular current star formation rates appear to cover a larger range than
expected based on the molecular gas masses. This behavior is consistent with
nuclear region star formation experiencing episodic variations. Under this
hypothesis the Milky Way's nuclear region currently may be in a low star
formation rate phase.

2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
14
The categories of this paper are: math-ph