Tarantula Nebula: Super-Sized Space Spider!

Narrator (April Hobart, CXC): Don't worry if you have a phobia of spiders, it is safe to keep watching! That's because this wonderful picture of a star-forming region called the Tarantula Nebula doesn't show the bright lines of gas that usually make it look like it has the legs of a spider.

Instead, this picture gives us an unusual view of the Tarantula Nebula. Astronomers had to combine observations made with two space telescopes to create this photo. It shows the X-ray radiation given off by very hot gas (the blue parts, captured by the Chandra X-ray Observatory) and the cooler gas that surrounds it (the orange parts, taken by the Spitzer Space Telescope).

The Tarantula Nebula is already big - it would take light about 650 years to cross from one end to the other - but it's getting even bigger! Astronomers have two ideas about what is causing the Tarantula's growth: Some astronomers think that explosions of the hot gas (shown in blue) are making it bigger, while others think that radiation from massive stars is causing the gas in the nebula to expand. To find out what is going on once and for all, astronomers need to take another look at this region.

When astronomers observe the Tarantula Nebula again, they won't be looking to prove their own ideas right. All they can do is look at what their observations tell them - even if it means acknowledging that they had been wrong.

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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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