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All posts for the month October, 2002

A spectrum showing lithium in a metal-poor star

A spectrum showing lithium in a metal-poor star

Not all the great stuff astronomers get the from sky is in the form of pretty pictures. Granted, gorgeous astrophotos are addictive, but they don’t tell the whole story of the universe. Astronomers also study data in the form of spectra. The figure above is a good example of a spectrum. Basically it tells astronomers that a star called G271-162 has a certain amount of an element called “lithium” — which is relatively rare in the cosmos compared to other elements. This star is what is known as a “metal-poor” star — one that formed in the earliest times of the universe. “Metal-rich” stars are those formed from interstellar gas and dust that has probably been “recycled” through at least one star and enriched with metals. So, if we study older stars like G271-162 and figure out how much they have of certain elements, that will tell us a lot about what elements were most plentiful in the early, early universe. Astronomers want to understand how much lithium was produced in the birth of the universe — the Big Bang — some 12 to 14 billion years ago. The amount of lithium older star will help them understand it.

You can’t take a picture of lithium, but you can study the light coming from a star — and break it up into a spectrum. If lithium is present in the star, it will show as a “dip” in the spectral line — which is exactly what you see in this graph.

Well, here I am again.

It was pointed out to me that Blogging is “In”. Sure, I saw the link to Time Magazine here. And, now PC Magazine has made it official with their article on Blogging in the new issue. Life on the cutting edge, eh?

So, I’m working on this script about Hubble Space Telescope science and I keep wondering how much people really know about this magnificent telescope and the things it is revealing to all of us. In January I was attending the American Astronomical Society meeting in Washington, D.C. and had a chance to visit a new exhibit at the National Air and Space Museum. The exhibition, titled Explore the Universe, features the Kodak-built back-up mirror for the HST. I found it really impressive. For the first time I could measure my height against a mirror the one that is capturing the photons from so many interesting things in the cosmos! I mean, I always knew I could comfortably stand inside the telescope tube, but seeing a mirror built to fit in that tube finally made the connection. If you’re in Washington, D.C., you should check it out — admission is free!

Of course there ARE bigger ground-based mirrors. I remember visiting the 100-inch on Palomar Mountain a few years back. And many of the installations on Kitt Peak in Arizona. And the twin eyes of the Keck telescopes at Mauna Kea, Hawaii. They look incredibly huge and somehow delicate during a daytime visit, but at night, these (along with the orbiting telescopes like HST, Chandra, etc.) that we use to focus on “stuff” of the universe, are the heavy lifters of Big Astronomy.

Well, it’s time to get back to the script. Anything you wanna know about? Write me at: CC dot petersen at hot mail dot com