Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Liquid metallic hydrogen and the structure of brown dwarfs and giant
  planets   Electron-degenerate, pressure-ionized hydrogen (usually referred to as
metallic hydrogen) is the principal constituent of brown dwarfs, the
long-sought objects which lie in the mass range between the lowest-mass stars
(about eighty times the mass of Jupiter) and the giant planets. The
thermodynamics and transport properties of metallic hydrogen are important for
understanding the properties of these objects, which, unlike stars, continually
and slowly cool from initial nondegenerate (gaseous) states. Within the last
year, a brown dwarf (Gliese 229 B) has been detected and its spectrum observed
and analyzed, and several examples of extrasolar giant planets have been
discovered. The brown dwarf appears to have a mass of about forty to fifty
Jupiter masses and is now too cool to be fusing hydrogen or deuterium, although
we predict that it will have consumed all of its primordial deuterium. This
paper reviews the current understanding of the interrelationship between its
interior properties and its observed spectrum, and also discusses the current
status of research on the structure of giant planets, both in our solar system
and elsewhere.

22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th