Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Tiny HI Clouds in the Local ISM   We report deep, high spectral resolution WSRT HI 21cm observations of four
high latitude compact radio sources, that have revealed a new population of
tiny, discrete clouds in the diffuse ISM, with peak optical depths tau ~
0.1-2%, HI column densities of 0.4-8 * 10^{18} cm^{-2} and core temperatures of
20-80 K. Imaging detections confirm these low column densities and imply linear
core dimensions of a few thousand AU, assuming a distance of 100 pc. The
physical origin of these tiny HI structures and their distribution in the ISM
is at present unknown. Further observations will be required to determine
whether they are a ubiquitous component of the ISM.

17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg