Circumstellar/Protoplanetary Disks and Bipolar Jets at5 AU Resolution

摘要

We present images of LDN 1551 IRS 5 at angular resolutions ashigh as ~30 mas, corresponding to a spatial resolution of~5AU, made at 7 mmwith the VLA. Previously known to be a binary protostellar system, we show thatLDN 1551 IRS 5 is probably a triple protostellar system. The primary and sec-ondary components have a projected separation of ~46 AU, whereas the tertiarycomponent has a projected separation of ~11 AU from the primary component.The circumstellar dust disks of all three components have dimensions of 15 AU. Their major axes are closely, but not perfectly, aligned with each otherand with the major axis of the surrounding flattened, rotating, and contractingmolecular condensation (pseudodisk). Furthermore, the orbital motions of theprimary and secondary components are in the same direction as the rotationalmotion of this pseudodisk. We suggest that all three protostellar componentsformed as a result of the fragmentation of the central region of the molecu-lar pseudodisk. Both the primary and secondary components, but apparentlynot the tertiary component, exhibit a bipolar ionized jet that is centered on andemerges perpendicular to its associated dust disk. Neither jets are resolved alongtheir base, implying that they are driven within a radial distance of ~2.5 AUfrom their central protostars. Our images provide an exciting preview of whatALMA is likely to obtain for many more protostellar systems.