For the normal star HD 162817, it was assumed that there was
no magnetic field. Microturbulence was also assumed to be absent
in the atmosphere of this star. While this may not be strictly correct
for a star with Teff 10 000 K, there are no discrepancies between
our synthetic and observed spectra of the type one would expect if
there were a significant microturbulence. Both weaker and stronger
lines of the same species are well fit with a single abundance value.
However, due to the higher projected rotational velocities of this star
and our program stars, few (if any) weak lines (on the linear part of
the curve of growth) are actually detected and modelled. Therefore
undetected microturbulence may exist, but would have an impact,
at most, at the level of our uncertainty in abundance. For example,
a 1 km s−1 microturbulence would decrease our abundance values
for this star by at most 0.1 dex.
For all program stars exceptHD320764, microturbulencewas assumed
to be suppressed, either directly or indirectly, by the presence
of a magnetic field. Therefore, no microturbulence was assumed in
computing the line profiles of HD 162305, HD 162576 and HD
162725. For HD 320764 a 1 km s−1 microturbulence was assumed.
In this star, it proved impossible to determine a microturbulence observationally.
The very large rotational broadening makes finding
the necessary mix of weak and strong lines of the same species impossible.
However, for a normalAstar with a temperature of 8800 K,
we expect there to be a small microturbulence (Landstreet 1998), so
a conservative value of 1 km s−1 was chosen.