Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dark Filaments in the Galaxy NGC 253 - a Boiling Galactic Disk -   We study the morphology of dark lanes and filaments in the dust-rich galaxy
NGC 253 using an unsharp-masked $B$-band optical photograph. Dust features are
classified as `arcs', which have heights and scale radius of about 100 to 300
pc, connecting two or more dark clouds, and `loops' and `bubbles', which are
developed forms of arcs, expanding into the disk-halo interface. These have
diameters of a few hundred pc to $\sim 1$ kpc. Among the bubbles, we notice a
peculiar round-shaped bubble above the nucleus, which could be a large-diameter
($\sim 300$ pc) supernova remnant exploded in the halo over the nucleus. We
also find `vertical dust streamers', which comprise bunches of narrow filaments
with a thickness of a few tens of pc and are almost perpendicular to the
galactic plane, extending coherently for 1 to 2 kpc toward the halo. Finally,
we note `short vertical dust filaments' (or spicules) are found in the central
region. We interpret these features as due to three-dimensional structures of
gas extending from the disk into the halo. We propose a `boiling disk' model
where the filamentary features are produced by star-forming activity in the
disk as well as the influence of magnetic fluxes. We discuss the implication of
the model for the chemical evolution of the ISM in a galaxy disk.

21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
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The categories of this paper are: econ
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin