Jets and Outflows from Star to Cloud: Observations Confront Theory

In this review we focus on the role jets and outflows play in the star- and planet-formation process. Our essential question can be posed as follows: Are jets/outflows merely an epiphenomenon associated with star formation, or do they play an important role in mediating the physics of assembling stars both individually and globally? We address this question by reviewing the current state of observations and their key points of contact with theory. Our review of jet/outflow phenomena is organized into three length-scale domains: (1) source and disk scales (0.1-102 AU) where the connection with protostellar and disk evolution theories is paramount; (2) envelope scales (102-105 AU) where the chemistry and propagation shed further light on the jet launching process, its variability and its impact on the infalling envelope; and (3) parent cloud scales (105-106 AU) where global momentum injection into cluster/cloud environments become relevant. Issues of feedback are of particular importance on the smallest scales, where planet formation regions in a disk may be impacted by the presence of disk winds, irradiation by jet shocks, or shielding by the winds. Feedback on envelope scales may determine the final stellar mass (core-to-star efficiency) and envelope dissipation. Feedback also plays an important role on the larger scales with outflows contributing to turbulent support within clusters, including alteration of cluster star-formation efficiencies (SFEs) (feedback on larger scales currently appears unlikely). In describing these observations we also look to the future and consider the questions that new facilities such as the Atacama Large Millimeter/submillimeter Array (ALMA) and the Jansky Array can address. A particularly novel dimension of our review is that we consider results on jet dynamics from the emerging field of high-energy-density laboratory astrophysics (HEDLA), which is now providing direct insights into the three-dimesional dynamics of fully magnetized, hypersonic, radiative outflows.