Posts Tagged ‘hubble’

Double Checking Our Data

Wednesday, November 26th, 2008 by Bellatrix

Scientists believe they have found the answer to a mystery about a thought to be nearby galaxy. The funny thing is this answer was found by rather serendipitously after finding out our current estimates for the distance of the galaxy were wrong.

The galaxy named NGC 1569 was a bit of a mystery. It is an irregular shaped dwarf galaxy, which isn’t in itself strange, but the galaxy was going through a burst of star formation with no discernable reason. The galaxy was forming stars much faster than any other galaxies in its nearby region. Well then we realized that the problem with that statement was not NGC 1569 itself but the galaxies we thought were nearby it.

Scientists recently pointed the Hubble Space telescope at NGC 1569 to scan for red giant stars. The astronomers were hoping to get an estimate of the galaxies age by looking for red giants, as red giants can be used as reliable standard candles for measuring distance since they all burn at the same known brightness. However, the astronomers were only able to see the brightest red giants, even using Hubble, the stars were too dim to be resolved. This fact lead astronomers to question the previous estimate for how far away the galaxy actually is. And now after looking at the data astronomers have realized the galaxy is actually about one and a half times farther away than previously thought, making it about 11 million light years away.

The problem was before this the galaxy had only been studied with ground based telescopes, which have much less resolving power than space based telescopes, which can make estimates less accurate. With this new information the galaxy’s star formation makes more sense. This distance puts the galaxy in the middle of a cluster of ten other galaxies. The gravitational interaction of the galaxies tugging on each other would be enough to explain the high rate of star formation we see in this galaxy.

So using Hubble we have answered yet another question, good ol’Hubble. However, this instance makes one wonder how many other numbers that we have for things like distance or mass etc might be inaccurate after only being studied by ground-based telescopes. How many things should we go back over with space-based telescopes to make sure? And how many mysteries or unexplainable phenomena might be answered by simply rechecking our data??

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Very Large Binoculars; Not for Bird Watching

Monday, October 20th, 2008 by Bellatrix

Recently an exciting new type of ground-based telescope came online. It is a collaboration between the University of Arizona, the National Institute of Astrophysics in Italy, and several institutions in Germany. It is an innovative idea to use two large mirrors for the telescope, like a pair of binoculars. This will give the telescope a large collecting area while avoiding complications of making one very large mirror.

The idea first started back in 1992 between Arizona and Italy. They only had the funding to make one mirror, but in 1997 with the addition of Germany and Ohio State University, the project was under way. The telescope mount was constructed in Italy and shipped to Arizona, where it joined the mirrors being constructed. The observatory will be part of the Mt. Graham International Observatory near Safford, Arizona.

The telescope will consist of two 8.54-meter mirrors on a shared mount, which has the light gathering power equivalent to one 11.8-meter mirror and a resolving power of a 22.8-meter mirror. The building of the two mirrors is a delicate and complicated process. The mirrors must go through an extensive annealing and cooling process. Then two tons of glass are added and then a slow heating process started, then another round of annealing and cooling. During this process glass leaks are possible which can really complicate things. Once finished the mirror mold must be cleaned and polished very carefully and exactly. The mirrors must stay in a temperature-controlled environment to prevent temperature changes affecting the surface of the mirrors.

The first primary mirror saw first light in 2005, but it wasn’t until 2008 that both mirrors came online together. The optical instruments include a UV spectrograph, thermal infrared imager, near infrared camera, high-resolution optical spectrograph, optical direct imager, and more. The telescope is designed for observing in the UV, optical, and infrared wavelengths.

The Large Binocular Telescope observatory (LBT) is the world’s highest resolution and most technologically advanced optical telescope, creating images in the near infrared with 10 times the resolution of the Hubble Space Telescope. There should be some exciting new developments coming from the LBT once it really gets going. It is a great example of innovation and ingenuity to overcome the technological obstacles of making very large mirrors and by using an array of smaller (yet still large) mirrors.

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