  The firehose and mirror instabilities are thought to arise in a variety of
space and astrophysical plasmas, constraining the pressure anisotropies and
drifts between particle species. The plasma stability depends on all species
simultaneously, meaning that a combined analysis is required. Here, we present
the first such analysis in the solar wind, using the long-wavelength stability
parameters to combine the anisotropies and drifts of all major species (core
and beam protons, alphas, and electrons). At the threshold, the firehose
parameter was found to be dominated by protons (67%), but also to have
significant contributions from electrons (18%) and alphas (15%). Drifts were
also found to be important, contributing 57% in the presence of a proton beam.
A similar situation was found for the mirror, with contributions of 61%, 28%,
and 11% for protons, electrons, and alphas, respectively. The parallel electric
field contribution, however, was found to be small at 9%. Overall, the
long-wavelength thresholds constrain the data well (<1% unstable), and the
implications of this are discussed.
