Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Planetary Accretion Shock: I. Framework for Radiation-hydrodynamical
  Simulations and First Results   The key aspect determining the post-formation luminosity of gas giants has
long been considered to be the energetics of the accretion shock at the
planetary surface. We use 1D radiation-hydrodynamical simulations to study the
radiative loss efficiency and to obtain post-shock temperatures and pressures
and thus entropies. The efficiency is defined as the fraction of the total
incoming energy flux which escapes the system (roughly the Hill sphere), taking
into account the energy recycling which occurs ahead of the shock in a
radiative precursor. We focus here on a constant equation of state to isolate
the shock physics but use constant and tabulated opacities. While robust
quantitative results will require a self-consistent treatment including
hydrogen dissocation and ionization, the results show the correct qualitative
behavior and can be understood semi-analytically. The shock is found to be
isothermal and supercritical for a range of conditions relevant to core
accretion (CA), with Mach numbers greater than ca. 3. Across the shock, the
entropy decreases significantly, by a few entropy units (k_B/baryon). While
nearly 100 percent of the incoming kinetic energy is converted to radiation
locally, the efficiencies are found to be as low as roughly 40 percent,
implying that a meaningful fraction of the total accretion energy is brought
into the planet. For realistic parameter combinations in the CA scenario, a
non-zero fraction of the luminosity always escapes the system. This luminosity
could explain, at least in part, recent observations in the LkCa 15 and HD
100546 systems.

37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math