Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: HST observations of the blue compact dwarf SBS 0335-052: a probable
  young galaxy   We present HST WFPC2 V and I images and GHRS UV spectrophotometry of the
spectral regions around Ly$_alpha$ and OI 1302 of the extremely metal-deficient
(Z~Zsun/41) blue compact dwarf (BCD) galaxy SBS 0335-052. All the star
formation in the BCD occurs in six super-star clusters (SSC) with ages =< 3-4
Myr. Dust is clearly present and mixed spatially with the SSCs. There is a
supershell of radius ~380 pc, delineating a large supernova cavity. The
instantaneous star formation rate is ~0.4 Msun yr^-1. Strong narrow Ly$\alpha$
emission is not observed. Rather there is low intensity broad (FWZI = 20 A)
Ly$\alpha$ emission superposed on even broader Ly$\alpha$ absorption by the HI
envelope. This broad low-intensity emission is probably caused by resonant
scattering of Ly$\alpha$ photons. The BCD appears to be a young galaxy,
undergoing its very first burst of star formation. This conclusion is based on
the following evidence: 1) the underlying extended low-surface-brightness
component is very irregular and filamentary, suggesting that a significant part
of the emission comes from ionized gas; 2) it has very blue colors (-0.34 =<
(V-I)$_0$ =< 0.16), consistent with gaseous emission colors; 3) the OI 1302
line is not detected in absorption in the GHRS spectrum, setting an upper limit
for N(O)/N(H) in the HI envelope of the BCD of more than 3000 times smaller
than the value in Orion.

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The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat