MIRA's wind explored in scattering infrared CO lines

We have observed the intermediate regions of the circumstellar envelope of Mira (o Ceti) in photospheric light scattered by three vibration-rotation t ransitions of the fundamental band of CO, from low-excited rotational level s of the ground vibrational state, at an angular distance of beta similar t o2"-7" away from the star. The data were obtained with the Phoenix spectrom eter mounted on the 4 m Mayall telescope at Kitt Peak. The spatial resoluti on is approximately and seeing limited. Our observations provide 0".5 absol ute fluxes, leading to an independent new estimate of the mass-loss rate of approximately 3 x 10(-7) M-circle dot yr(-1), as derived from a simple ana lytic wind model. We find that the scattered intensity from the wind of Mir a for 2" less than or similar to beta less than or similar to 7" decreases as beta (-3), which suggests a time constant mass-loss rate, when averaged over 100 yr, over the past 1200 yr.