Friday, October 03, 2008

The Center For Backyard Astrophysics

One cool thing about astronomy as a science, something quite different from almost all the other sciences, is that in astronomy it is not too unusual for the work of amateurs to find a place right next to the work of professionals.

Even in this era of robotic telescopes and automated sky surveys, every year amateur astronomers discover new comets, new novae and maintain data on variable star fluctuations.

My pick for the coolest thing amateur astronomers have ever participated in happened two years ago about this time of year. It started, in fact, in Japan on Halloween night

An accomplished Japanese amateur astronomer, Akihiko Tago, discovered that an obscure dim star in the constellation Cassiopeia had suddenly become fifty times brighter than normal. He reported his find to the astronomy world’s central clearinghouse of information and they immediately announced the discovery via email to professional and amateur astronomers all around the world.

Professionals and amateurs turned their attention to Cassiopeia. Professionals began to try to figure out exactly what kind of event was taking place. Was the star going nova? Was it a normal star suddenly turning variable?

One group of amateurs who responded enthusiastically was the Center for Backyard Astrophysics. This is a world-wide group of astronomy buffs who all have equipment optimized for studying variable stars. This group collected data on the strange star in Cassiopeia night after night, documenting the star as it slowly faded back to its normal magnitude.

Professional astronomers and astrophysicists eventually concluded that an obscure bit of Einstein-type physics had taken place—a small star had passed directly between the Earth and the star in Cassiopeia and the gravity of that small star had created a gravity lens, specifically a micro-lens event. Space itself had become bent and gathered light from the distant star and focused it on the Earth.

Such events had been witnessed before, but only involving stars from outside our own galaxy.

One of the distinguishing characteristics of such an event is the manner in which the star’s light brightens and then returns to normal. All the data gathered by members of the Center for Backyard Astrophysics were used by professional astronomers and astrophysicists to plot the curve of the changes in the star’s light. The curve conformed perfectly to what the physics of a micro-lens event predicted.

Pretty cool stuff.

The amateurs work with generally off-the-shelf equipment. Telescopes between 8 inches and 30 inches. Standard electronic imaging equipment. They have some custom software they share among themselves for processing their nightly images, but the software runs on normal computers.

Pretty cool stuff.

(But I will be honest: Although this is my favorite episode of amateurs working with professionals, the whole field of variable star observing always has seemed indescribably boring to me. It is, I think, the one sub-field of astronomy that I have never personally participated in. I sometimes wonder about my own lack of interest in the activity because I think the astrophysics of variables stars is very interesting and I strongly suspect studies of variable stars will someday yield surprising discoveries. It’s strange: I think it’s cool and interesting, but I feel no imperative do it . . .)

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Sky & Telescope magazine
published an interesting article
on the Cassiopeia event in their
July, 2008, issue.

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