Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Stagger-grid: A grid of 3D stellar atmosphere models - VI. Surface
  appearance of stellar granulation   In the surface layers of late-type stars, stellar convection is manifested
with its typical granulation pattern due to the presence of convective motions.
The resulting photospheric up- and downflows leave imprints in the observed
spectral line profiles. We perform a careful statistical analysis of stellar
granulation and its properties for different stellar parameters. We employ
realistic 3D radiative hydrodynamic (RHD) simulations of surface convection
from the Stagger-grid, a comprehensive grid of atmosphere models that covers a
large parameter space in terms of Teff, logg, and [Fe/H]. Individual granules
are detected from the (bolometric) intensity maps at disk center with an
efficient granulation pattern recognition algorithm. From these we derive their
respective properties: diameter, fractal dimension (area-perimeter relation),
geometry, topology, variation of intensity, temperature, density and velocity
with granule size. Also, the correlation of the physical properties at the
optical surface are studied. We find in all of our 3D RHD simulations stellar
granulation patterns imprinted, which are qualitatively similar to the solar
case, despite the large differences in stellar parameters. The granules exhibit
a large range in size, which can be divided into two groups - smaller and
larger granules - by the mean granule size. These are distinct in their
properties: smaller granules are regular shaped and dimmer, while the larger
ones are increasingly irregular and more complex in their shapes and
distribution in intensity contrast. This is reflected in their fractal
dimensions, which is close to unity for the smaller granules, and close to two
for larger granules, which is due to the fragmentation of granules. Stellar
surface convection seems to operate scale-invariant over a large range in
stellar parameters, which translates into a self-similar stellar granulation
pattern.

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The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
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The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
30
The categories of this paper are: q-alg
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The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
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The categories of this paper are: supr-con
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The categories of this paper are: q-fin