Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Sample of OB Stars That Formed in the Field   We present a sample of 14 OB stars in the Small Magellanic Cloud that meet
strong criteria for having formed under extremely sparse star-forming
conditions in the field. These stars are a minimum of 28 pc in projection from
other OB stars, and they are centered within symmetric, round HII regions. They
show no evidence of bow shocks, implying that the targets are not transverse
runaway stars. Their radial velocities relative to local HI also indicate that
they are not line-of-sight runaway stars. A friends-of-friends analysis shows
that 9 of the objects present a few low-mass companion stars, with typical mass
ratios for the two highest-mass stars of around 0.1. This further substantiates
that these OB stars formed in place, and that they can and do form in extremely
sparse conditions. This poses strong constraints on theories of star formation
and challenges proposed relations between cluster mass and maximum stellar
mass.

13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys