Ejection of bullets from the star-formation region in Orion KL

The structure of compact ejections, or bullets, is studied in water-vapor lines at an angular resolution of similar to 0.1 milliarcsec. A relationship between the ejections and outbursts in the H(2)O supermaser emission is found. The bullet speeds reach 12-19 km/s. The characteristic ejection time for a bullet, i.e., a matter outflow with enhanced speed and density, can reach several months, and corresponds to the duration of the supermaser outburst. Certain characteristic structures are typical of the bullets, such as compact features corresponding to the ejection of condensed ice granules, cometary structures with tails either preceding or following the heads (depending on the relative velocity), and bullets extending to 4 AU (fragments of a bipolar outflow enriched in water molecules). The cross section of the flow (i.e., of the bullets) is of the order of 0.1 AU and is preserved to distances of about 80 AU. The distribution of the bullets within the cone similar to 15A degrees is related to the precession of the ejector. The maximum brightness temperatures of the bullets reach T(b) similar to 10(14) K at a speed of 7.65 km/s, which corresponds to the local standard of rest. The increased brightness temperature is due to the enhancement of the bullets by one or two orders of magnitude in the surrounding envelope.