PROTOSTELLAR JETS IRRADIATED BY MASSIVE STARS

The formation of solar-type stars is a gradual process during which th ey accrete mass from the dense disks and cloud cores that surround the m. This accretion requires the release of angular momentum, and an imp ortant mechanism for achieving this seems to be the production of jets along the polar axes of the young stars(1,2), But the presence of mas sive, luminous stars within the same star-forming region can affect th e forming stars by stripping away their circumstellar envelopes with u ltraviolet radiation, thereby removing the reservoir of gas from which the stars are built up and exposing the disks to photoerosion(3). Her e we present observations of four highly collimated jets from young st ars that appear to have been stripped of their circumstellar molecular cloud cores in this way. The production of jets seems to have been la rgely unaffected. If these jets are also photoionized, their mass loss rates can be determined from observations with much greater accuracy than for normal shock-excited jets.