标题： 200度长的麦哲伦流系统 显示英文标题

标题： The 200 Degree-Long Magellanic Stream System

摘要： 我们确定麦哲伦流（MS）比之前已知的长约40度，因此整个MS和前导臂（LA）系统至少长200度。 使用GBT，我们在MS末端进行了约200平方度的21厘米巡天，以证实Hulsbosch与Wakker的数据和Braun与Thilker报告的类似MS发射之间的连续性。 我们的调查结合Stanimirovic等人在阿雷西博的调查表明，MS气体在这个区域是连续的，并且MS至少长约140度。 我们在MS东侧发现了一条新的细丝，它偏离MS坐标系的赤道超过约45度。 此外，我们在MS末端附近L_MS=-120度处发现了先前未知的速度拐点，在该点速度达到最小值然后开始增加。 我们发现de Heij等人分类的五个紧凑高纬云以及Wright的云可能与MS有关，因为它们在位置和速度上与MS匹配。 新确认的MS末端约40度延伸的质量约为2×10^7 Msun（d/120 kpc）^2（包括Wright的云会使这一数值增加约50%），这使得MS的总质量增加了约4%。 然而，MS末端的投影模型距离通常相当大，如果属实，则表明这一延伸部分的质量可能高达约10^8 Msun。 从我们整个MS的综合地图来看，我们发现总柱密度（沿MS横向积分）沿着MS显著下降，并随L_MS呈指数衰减。 我们估计约140度长的MS的年龄约为25亿年，这与麦哲伦云中的恒星形成爆发相吻合，也可能是这两颗星系之间可能发生的一次近距离相遇，这次相遇可能触发了MS的形成。[摘要] 显示英文摘要

摘要： We establish that the Magellanic Stream (MS) is some 40 degrees longer than previously known with certainty and that the entire MS and Leading Arm (LA) system is thus at least 200 degrees long. With the GBT, we conducted a ~200 square degree, 21-cm survey at the MS-tip 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 ~140 degrees long. 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 ~45 degrees. Additionally, we find a previously unknown velocity inflection in the MS-tip near MS longitude L_MS=-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 ~40 degree extension of the MS-tip is ~2x10^7 Msun (d/120 kpc)^2 (including Wright's Cloud increases this by ~50%) and increases the total mass of the MS by ~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 ~10^8 Msun. 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. We estimate that the age of the ~140 degree-long MS is ~2.5 Gyr which 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. [Abridged]