Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Compact radio sources in M17   The classic HII region M17 is one of the best studied across the
electromagnetic spectrum. We present sensitive, high angular resolution
observations made with the Jansky Very Large Array (JVLA) at 4.96 and 8.46 GHz
that reveal the presence of 38 compact radio sources, in addition to the well
known hypercompact cometary HII region M17 UC1. For this last source we find
that its spectral index of value $\sim$1 is due to a gradient in opacity across
its face. Of the 38 compact radio sources detected, 19 have stellar
counterparts detected in the infrared, optical, or X-rays. Finally, we discuss
the nature of the radio emission from the massive binary system CEN 1a and 1b,
concluding that both are most probably non-thermal emitters, although the first
is strongly time variable and the second is steady.

35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat