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Science:土星最大的卫星上发现了被淹没的峡谷

标签:土星 泰坦 液体
摘要 : 一项新研究表明,在土星最大的卫星泰坦上,围绕着一片甲烷海的陡峭峡谷部分灌满了液体,那些流入峡谷的长长的河网支流也是如此。

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一项新研究表明,在土星最大的卫星泰坦上,围绕着一片甲烷海的陡峭峡谷部分灌满了液体,那些流入峡谷的长长的河网支流也是如此。天文学家利用卡西尼号探测器飞过泰坦时采集的雷达数据确定了峡谷的底部范围,经测量其宽度不到一公里,最深处可达570米,且大体平坦,地貌上没有高于2.7毫米的地方。研究人员提出,这里比地球上任何的自然地貌都更平坦,所以强有力地暗示峡谷灌满了液体。此外,峡谷底部的水平高度与海面持平,这是另一条线索,暗示这里的物质是可以流动的液体,研究团队本周在《地球物理学研究通讯》网络版上报告了这一发现。由于峡谷既陡峭又辽阔,所以海平面的高度应该一度远低于现在的水平,到后来才上升并填满这个被河流环绕的峡谷。在此之前,我们并不确定峡谷看起来很暗是因为它们满是吸收雷达的物质,还是因为观察角度产生的阴影。卡西尼号该次飞掠所采集的雷达数据示意,该河网中的多条支流里同样充满了液体(从上图右下角流向海里),研究人员提醒:这只是一个线索,不是证据,暗示这些河流仍在主动地侵蚀泰坦的表面。

原文链接:

Flooded canyons spotted on Saturn’s largest moon

原文摘要:

Some of the steep canyons that fringe a methane sea on Titan, Saturn’s largest moon, are filled with liquid—and so are the tributaries of lengthy river network that flow into them, a new study suggests. Using radar data gathered by the Cassini probe during a fly-by, astronomers determined the floors of the canyons—which measure less than a kilometer wide and are up to 570 meters deep—were essentially flat, with no features larger than 2.7 millimeters high. That’s flatter than any natural feature on Earth, so it’s a strong sign the canyons are filled with liquid, the researchers propose. Plus, the level of the canyon floors matches that of the sea, another clue that the material is liquid that can flow, the team reports online this week in Geophysical Research Letters. Because the canyons are both steep-sided and broad, the surface of the sea must have been much lower at one time, only later rising to fill the river-carved gorges with liquid. Previously, it wasn’t clear whether the canyons seemed dark because they were filled with a radar-absorbing material or were being seen from an angle and therefore in shadow. Radar data gathered during the same flyby hint that several tributaries in the river network (seen flowing to the sea from the lower right corner of the image) also contain liquid, a hint—but not proof, the researchers caution—that these rivers are still actively eroding Titan’s surface.

来源: Science 浏览次数:0

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