THE 200° LONG MAGELLANIC STREAM SYSTEM

We establish with certainty that the Magellanic Stream (MS) is some 40 degrees longer than previously known and that the entire MS and Leading Arm system is thus at least 200 degrees long. With the Green Bank Telescope (GBT), we conducted a similar to 200 deg(2), 21 cm survey at the tip of the MS to substantiate the continuity of the MS between the Hulsbosch & Wakker data and the MS-like emission reported by Braun & Thilker. Our survey, in combination with the Arecibo survey by Stanimirovic et al., shows that the MS gas is continuous in this region and that the MS is at least similar to 140 degrees. long. The MS tip is composed of a multitude of forks and filaments. We identify a new filament on the eastern side of the MS that significantly deviates from the equator of the MS coordinate system for more than similar to 45 degrees. Additionally, we find a previously unknown velocity inflection in the MS tip near MS longitude L(MS) approximate to -120 degrees at which the velocity reaches a minimum and then starts to increase. We find that five compact high-velocity clouds cataloged by de Heij et al. as well as Wright's Cloud are plausibly associated with the MS because they match the MS in position and velocity. The mass of the newly confirmed similar to 40 degrees extension of the MS tip is similar to 2 x 10(7)M(circle dot) (d/120 kpc)(2) (including Wright's Cloud increases this by similar to 50%) and increases the total mass of the MS by similar to 4%. However, projected model distances of the MS at the tip are generally quite large and, if true, indicate that the mass of the extension might be as large as similar to 10(8) M(circle dot). From our combined map of the entire MS, we find that the total column density (integrated transverse to the MS) drops markedly along the MS and follows an exponential decline with L(MS) of N(HI) = 5.9 x 10(21) exp(L(MS)/19.degrees 3) cm(-2). Under the assumption that the observed sinusoidal velocity pattern of the LMC filament of the MS is due to the origin of the MS from a rotating LMC, we estimate that the age of the similar to 140 degrees long MS is similar to 2.5Gyr. This coincides with bursts of star formation in the Magellanic Clouds and a possible close encounter of these two galaxies with each other that could have triggered the formation of the MS. These newly observed characteristics of the MS offer additional constraints for MS simulations. In the Appendix, we describe a previously little discussed problem with a standing wave pattern in GBT Hi data and detail a method for removing it.