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Tour: Cosmic Hand Hitting a Wall

Astronomers have measured motions within a remarkable cosmic structure for the first time using NASA's Chandra X-ray Observatory. The data show a blast wave and debris from an exploded star moving away from the explosion site and colliding with a wall of surrounding gas. Researchers estimate that light from this explosion, or supernova, reached Earth about 1,700 years ago when the Mayan empire was flourishing and the Jin dynasty ruled China. However, by cosmic standards the supernova remnant formed by the explosion, which occurred when a massive star ran out of fuel and collapsed, is one of the youngest in the Milky Way galaxy. The explosion also created an ultra-dense, magnetized star called a pulsar, which then blew a bubble of energetic particles. Scientists call this structure a nebula and Chandra reveals that is emitting X-rays.

Since the explosion, the supernova remnant — made of debris from the shattered star, plus the explosion's blast wave — and the X-ray nebula, have been changing as they expand outward into space. Notably, the supernova remnant and X-ray nebula now resemble the shape of fingers and a palm.

In 2009, another team of astronomers released a full Chandra view of the "hand," as shown in the main graphic. In a new study, scientists now report how quickly the supernova remnant associated with the hand is moving, as it strikes a cloud of gas to the north, called RCW 89. The inner edge of this cloud forms a gas wall located about 35 light-years from the center of the explosion.

To track the motion, the team used Chandra data from 2004, 2008, and then a combined image from observations taken in late 2017 and early 2018. These three images are included in the inset and show the motion of the explosion's blast wave. This feature, which includes clumps of magnesium and neon, is moving at nearly 9 million miles per hour. Some other parts of the remnant are moving even more quickly at over 11 million miles per hour.

While these are startling high speeds for us on Earth, they actually represent a slowing down of the remnant. Researchers estimate that to reach the farthest edge of RCW 89, material would have to travel on average at almost 30 million miles per hour. They think this slowdown is caused by the material having passed through a low-density cavity of gas and then running into the denser environment of RCW 89.

It is details like these that help astronomers learn more about how some stars end their lives. This type of research has been central to Chandra mission since its launch over two decades ago and undoubtedly will continue to be a focus into the future.

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