"A supernova remnant near the centre of the Milky Way has turned out to be the youngest known in our galaxy, plugging a puzzling gap in the astronomical record.
Known as G1.9+0.3, the remnant lies about 28,000 light years away. It was first identified as a ring-like supernova remnant in the early 1980s. Now, observations by NASA's Chandra X-ray Observatory and the Very Large Array in New Mexico have shown that the diameter of the glowing gas shell has expanded by 16 per cent over the past 22 years.
If the speed of expansion is roughly constant, then the remnant is only about 140 years old, making it the youngest in the Milky Way. Previously, the most recent supernova was thought to have occurred around the year 1680, creating the ghostly remnant Cassiopeia A.
The latest supernova would not have been visible to 19th-century astronomers because it occurred in dense gas and dust near the galactic centre. "The best telescopes at that time would not have been able to collect enough light to see it," says Stephen Reynolds of North Carolina State University in Raleigh, who led the Chandra study and revealed the results this week. "But the remnant shines in radio waves and X-rays, so X-ray and radio telescopes can see it.""
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