Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: SBS 0335-052 E and W: implications of new broad-band and H-alpha
  photometry   We present the results of deep multicolour CCD imaging with the 6-m telescope
of the pair of extremely metal-deficient gas-rich dwarf galaxies SBS 0335-052 E
and W. The total magnitudes in U,B,V,R,I bands and the integrated fluxes of
H-alpha emission are measured for both galaxies, and their integrated colours
are derived. The analysis of their surface brightness (SB) distributions is
performed with the use of the azimuthally-averaged SB profiles. The latter were
modeled by the central Gaussian component and the underlying exponential
`disk', mainly contributing in the outermost, very low SB regions. The colours
of these LSB components are used to estimate the age of the oldest visible
stellar population. For the interpretation of the observed LSB colours their
contamination by the nebular emission of ionized gas is accounted for by the
use of the distribution of H-alpha flux. We compare the derived `gas-free'
colours with the colours predicted by the evolution synthesis models from the
PEGASE.2 package, considering three SF histories: a) instantaneous starburst,
b) continuous star formation with constant SFR, c) continuous exponentially
fading SF (e-fold time of 3 Gyr). We conclude that the `gas-free' colours of
the LSB component of the E galaxy can be best consistent with the instantaneous
starburst population (ages of less than ~100 Myr). Models with continuous SF
give less consistent results, but can be considered as acceptable. For such
scenarios, the `gas-free' colours require ages of less than ~400 Myr. For the W
galaxy, the situation is in general similar. But the colour (V-R) appears to be
quite red and implies a significantly older component. We briefly discuss the
possible evolution sequence between SBS 0335-052, HI 1225+01 and other
extremely metal-deficient galaxies based on the merger scenario.

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The categories of this paper are: dg-ga
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The categories of this paper are: q-alg
1
The categories of this paper are: cs
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: funct-an
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-fin
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The categories of this paper are: econ
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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-th
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The categories of this paper are: chem-ph