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System parameters of the black-hole binary GRO J0422+32, in a very low
state
Natalie Webb (Keele)
Using the technique of placing two stars on the slit, we
simultaneously observed J0422+32 (I~20.4) and a local star (at
6900-9500 Angstroms), during December 1997. By dividing by the local
star, we have succesfully corrected for telluric absorption. To
correct for slit losses, we used simultaneous I band photometry. This
allows us to use the TiO bands at 7055 Angstroms and 7589 Angstroms,
from which we can gain a high signal-to-noise to do a more accurate
radial velocity study than has previously been done of this very faint
object. We have used the well-corrected TiO bands to classify the
secondary as an M4-5 star. We also present a new distance to the
system and the contributions of the secondary star and accretion disc
to the observed flux.
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