Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Resolving subdwarf B stars in binaries by HST imaging   The origin of subluminous B stars is still an unsolved problem in stellar
evolution. Single star as well as close binary evolution scenarios have been
invoked but until now have met with little success. We have carried out a small
survey of spectroscopic binary candidates (19 systems consisting of an sdB star
and late type companion) with the Planetary Camera of the WFPC2 onboard Hubble
Space Telescope to test these scenarios. Monte Carlo simulations indicate that
by imaging the programme stars in the R-band about one third of the sample (6-7
stars) should be resolved at a limiting angular resolution of 0.1" if they have
linear separations like main sequence stars ("single star evolution"). None
should be resolvable if all systems were produced by close binary evolution. In
addition we expect three triple systems to be present in our sample. Most of
these, if not all, should be resolvable. Components were resolved in 6 systems
with separations between 0.2" and 4.5". However, only in two systems do the
magnitudes of the resolved components match the expectations from the
deconvolution of the spectral energy distribution. These two stars could be
physical binaries whereas in the other cases the nearby star may be a chance
projection or a third component. Radial velocity measurements indicate that the
resolved system TON 139 is a triple system, with the sdB having a close
companion that does not contribute detectably to the integrated light of the
system. Accordingly the success rate would be only 5% which is clearly below
the prediction for single star evolution. We conclude that the distribution of
separations of sdB binaries deviates strongly from that of normal stars. Our
results add further evidence that close binary evolution is fundamental for the
evolution of sdB stars. (abbreviated)

8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
18
The categories of this paper are: econ