The Magellanic Stream
Abstract
We have performed a detailed HI study of the Magellanic Stream (MS). Using the LAB all-sky HI survey, we expose the MS to be composed of two filaments distinct both spatially and in velocity. One of the MS filaments and parts of the Leading Arm (LA) can be traced back to their origin in the SouthEast HI Overdensity (SEHO) of the LMC, which includes 30 Doradus. Therefore, at least one-half of the trailing Stream and most of the LA originates in the LMC, contrary to previous assertions that they originate in the SMC and/or in the Magellanic Bridge. The two MS filaments show periodic spatial and velocity patterns that we speculate are an imprint of the LMC rotation curve. If true, then the drift rate of the Stream gas away from the Magellanic Clouds is 49 km/s and the age of the MS is 1.74 Gyr. High-resolution HI data of the LMC show gas outflows from supergiant shells in the SEHO that seem to be creating the LA and LMC filament of the MS. We lay out a new model, the "Blowout Hypothesis", for the formation of the MS that fits all of the available data and solves some longstanding problems. We also conducted a 200 square degree HI survey with the GBT at the tip of the MS in order to bridge the gap between the 100 deg-long "classical" MS and the MS-like emission reported by Braun & Thilker (2004). Our survey shows that the MS gas is continuous across the gap and that the MS is at least 140 deg long. A previously unknown velocity inflection in the MS-tip is also revealed in the data. We fit an orbit to the MS velocity distribution and find a robust solution for the space velocity of the MS.
- Publication:
-
American Astronomical Society Meeting Abstracts #215
- Pub Date:
- January 2010
- Bibcode:
- 2010AAS...21531803N