A high-speed bipolar outflow from the archetypical pulsating star Mira A

Optical images and high-dispersion spectra have been obtained of the ejected material surrounding the pulsating AGB star Mira A. The two streams of knots on either side of the star, found in far-ultraviolet (FUV) GALEX images, have now been imaged clearly in the light of Ha. Spatially resolved profiles of the same line reveal that the bulk of these knots form a bipolar outflow with radial velocity extremes of + - 150 km s(-1) with respect to the central star. The south stream is approaching and the north stream receding from the observer. A displacement away from Mira A between the position of one of the south-stream knots in the new Ha image and its position in the previous Palomar Observatory Sky Survey (POSS I) red plate was noted. If interpreted as a consequence of expansion proper motions, the bipolar outflow is tilted at 69 degrees + - 15 degrees to the plane of the sky, has an outflow velocity of 160 + - 10 km s(-1) and is approximate to 1000 y old.