DISCOVERY OF A GIANT, HIGHLY COLLIMATED JET FROM SANDULEAK’S STAR IN THE LARGE MAGELLANIC CLOUD

摘要

Highly collimated gas ejections are among the most dramatic structures in the universe, observed to emerge from very different astrophysical systems—from active galactic nuclei down to young brown dwarf stars. Even with the huge span in spatial scales, there is convincing evidence that the physics at the origin of the phenomenon, namely, the acceleration and collimation mechanisms, is the same in all classes of jets. Here we report on the discovery of a giant, highly collimated jet from Sanduleak’s star in the Large Magellanic Cloud (LMC). With a physical extent of 14 pc at the distance of the LMC, it represents the largest stellar jet ever discovered, and the first resolved stellar jet beyond the MilkyWay. The kinematics and extreme chemical composition of the ejecta from Sanduleak’s star bear strong resemblance with the low-velocity remnants of SN1987A and with the outer filaments of the most famous supernova progenitor candidate, η Carinae. Moreover, the precise knowledge of the jets distance implies that it will be possible to derive accurate estimates of most of its physical properties. Sanduleak’s bipolar outflow will thus become a crucial test bed for future theoretical modeling of astrophysical jets.