A New Look at an Old Friend

Narrator (April Hobart, CXC): Just weeks after NASA's Chandra X-ray Observatory began operations in 1999, the telescope pointed at Centaurus A (Cen A, for short). This galaxy, at a distance of about 12 million light years from Earth, contains a gargantuan jet blasting away from a central supermassive black hole.

Since then, Chandra has returned its attention to this galaxy, each time gathering more data. And, like an old family photo that has been digitally restored, new processing techniques are providing astronomers with a new look at this old galactic friend.

This new image of Cen A contains data from observations, equivalent to over nine and a half days worth of observing time, taken between 1999 and 2012. In this image, the lowest-energy X-rays Chandra detects are in red, while the medium-energy X-rays are green, and the highest-energy ones are blue.

As in all of Chandra's images of Cen A, this one shows the spectacular jet of outflowing material that is generated by the giant black hole at the galaxy's center. The new image also highlights a dust lane that wraps around the waist of the galaxy. Astronomers think this feature is a remnant of a collision that Cen A experienced with a smaller galaxy millions of years ago.

In addition to allowing for the creation of new images, the data housed in Chandra's extensive archive on Cen A provide a rich resource for a wide range of scientific investigations. For example, just last year researchers published new findings on the point-like X-ray sources in Cen A. They found that these sources had masses that fell into two categories. These separate groups correspond to systems where either a neutron star or a black hole is pulling material from a companion star. Information like this may tell us important details about the way the massive stars explode, and gives us even more reason to appreciate this new view of a familiar object.

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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.