Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Extremely Red, Young L Dwarf PSO J318-22: A Free-Floating
  Planetary-Mass Analog to Directly Imaged Young Gas-Giant Planets   We have used Pan-STARRS1 to discover an extremely red late-L dwarf, which has
(J-K)_MKO = 2.84 and (J-K)_2MASS = 2.78, making it the reddest known field
dwarf and second only to 2MASS J1207-39b among substellar companions. Near-IR
spectroscopy shows a spectral type of L7 and reveals a triangular H-band
continuum and weak alkali (K I and Na I) lines, hallmarks of low surface
gravity. Near-IR astrometry from the Hawaii Infrared Parallax Program gives a
distance of 24.6+/-1.4 pc and indicates a much fainter J-band absolute
magnitude than field L dwarfs. The position and kinematics of PSO J318-22 point
to membership in the beta Pictoris moving group. Evolutionary models give a
temperature of 1160 (-40,+30) K and a mass of 6.5 (-1.0, +1.3) Mjup, making PSO
J318-22 one of the lowest mass free-floating objects in the solar neighborhood.
This object adds to the growing list of low-gravity field L dwarfs and is the
first to be strongly deficient in methane relative to its estimated
temperature. Comparing their spectra suggests that young L dwarfs with similar
ages and temperatures can have different spectral signatures of youth. For the
two objects with well constrained ages (PSO J318-22 and 2MASS J0355+11), we
find their temperatures are ~400 K cooler than field objects of similar
spectral type but their luminosities are comparable, i.e., these young L dwarfs
are very red and unusually cool but not "underluminous." Altogether, PSO
J318-22 is the first free-floating object with the colors, magnitudes,
spectrum, luminosity, and mass that overlap the young dusty planets around HR
8799 and 2MASS J1207-39.

7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph