W49B: A Study in Supernovas

Narrator (April Hobart, CXC): Like the famous detective Sherlock Holmes, astronomers have to be good at solving puzzles by piecing together clues and evidence. When scientists using the Chandra X-ray Observatory noticed the strange, distorted shape of this supernova remnant, they knew something unusual had taken place. After scouring through their data and arguing against other possibilities, astronomers realised they may have uncovered a dark secret lurking within this picture - a young black hole!

The supernova explosions that tear apart massive stars normally blast away material evenly in all directions and leave behind a symmetrical bubble (the same on both sides). However, in this supernova, material from the north and south poles of the star (yes, stars have poles, too!) was blasted out much faster than anywhere else. The resulting barrel-shaped remnant gave astronomers their first clue that this star's life ended in an unusual way.

Most of the time when a star goes supernova, the remaining core is squashed down into a tiny ball called a neutron star. Neutron stars normally give off X-ray radiation, which astronomers can photograph using special telescopes. But a careful search of the data showed no X-ray radiation or other evidence for a neutron star. This means an even more exotic object was probably formed during the explosion - a black hole! If this turns out to be correct, it'll be the youngest known black hole in our entire Galaxy, at just 27,000 years old!

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HD 189733: NASA's Chandra Sees Eclipsing Planet in X-rays for First Time

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Narrator (April Hobart, CXC): HD 189733b: An exoplanet in orbit around a star about 63 light years from Earth. It has been nearly two decades since the first exoplanets – that is, planets around stars other than our Sun – were discovered. Now for the first time, X-ray observations have detected an exoplanet passing in front of its parent star. The observations, made by NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton Observatory, took advantage of the alignment of a planet and its parent star in HD 189733. This alignment enabled the observatories to observe a dip in X-ray intensity as the planet moved in front of, or transited, the star. This technique is the one used so successfully at optical wavelengths by NASA's Kepler telescope. In earlier studies using optical light, astronomers discovered that the main star in the HD 189733 system had what is known as a "hot Jupiter" around it. This means the planet is about the size of Jupiter, but in very close orbit around its star. The planet – that has been named HD 189733b -- is over 30 times closer to its star than Earth is to the Sun, and goes around the star once every 2.2 days. The new X-ray data suggest that this planet has a larger atmosphere than previously thought. This, in turn, may imply that radiation from the parent star is evaporating the atmosphere of HD 189733b more quickly than expected. The results on HD 189733 demonstrate how we need information from many different telescopes that detect different types of light to get a fuller picture of these mysterious worlds that we are now able to explore.

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