The James Webb Space Telescope has had a lot of recent milestones. All the primary mirror segments have been polished – and the secondary mirror has just been completed. You can read a NASA web feature all about what Webb’s secondary mirror does and why it’s important. (It’s quite large too – nearly as big as the Spitzer Space Telescope’s primary mirror!)
Credit: Ball Aerospace
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Credit: Photo by Drew Noel
One of the James Webb Space Telescope’s many feats of engineering will be its actuators – tiny mechanical motors on the back of its primary and secondary mirror segments that will help the telescope focus by changing the mirrors’ curvature. You can’t see the actuator in the photo, because it’s behind the mirror! The Behind the Webb podcast just released an episode about this fascinating technology, called “Got Your Back.” You can watch it after the jump!
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Astronomical headlines are often written about an object that was observed recently. It could be about the brightest stellar flare ever seen, the most recently formed black hole, or a newly discovered eclipsing pulsar that allows a strict test of general relativity. But a few headlines are about the “dog that didn’t bark”, so to speak. This is a blog about one such headline.
You could compare this headline to the one that was on the sports section of newspapers all across the US on the morning of Monday, September 21, 1998. It wasn’t about an NFL quarterback who threw 4 touchdowns, it wasn’t about a multi home-run game by a baseball slugger or pennant clinching win by his team, and it wasn’t about a pre-season blockbuster trade in the NBA. It was about an athlete who didn’t play the previous day.
Back to astronomy. Dr. Kevin Schawinski of Yale and his collaborators published a paper with the title “the sudden death of the nearest quasar” in the 2010 November 20 issue of Astrophysical Journal Letters. This concerns a galaxy named IC 2497 and a cloud of ionized gas 45,000 to 70,000 light years away from it known as Hanny’s Voorwerp (Dutch for “Hanny’s Object”). The Voorwerp is a fascinating object in two ways. For one thing, there was no obvious explanation of why this cloud was so ionized. For another, it was actually discovered in 2007 by an amateur Galaxy Zoo project volunteer, Hanny van Arkel, a Dutch school teacher. (There’s even a comic book about the Voorwerp!)
Ground-based optical image of IC 2497 (top), Hanny’s Voorwerp (bottom), and a nearby
companion galaxy (left). This image is a composite of blue, visual, and near infrared light
images taken with the WIYN telescope. Credit: WIYN/William Keel/Anna Manning
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