Wednesday, January 1, 2014

An Old Star for the New Year

Happy next orbit around the Sun, everyone. The center of our beautiful new year photo shows a Hubble image of an old star that is going through a little bit of a crisis in its life (as older stars -- and people -- tend to do.) The star, called RS Puppis, is getting brighter and dimmer on a regular cycle every 41 days. Stars that become changeable like this for a short part of their lives are called "Cepheid Variable Stars."

RS Puppis is one of the brightest known Cepheids, shining on average 15,000 times brighter than the Sun. It contains about 10 times more material than our Sun, and is 200 times larger in extent (an earlier part of its life crisis was swelling up to be much bigger than stars usually are.)

Because this star is surrounded by a cocoon of dust, the changing light from it is seen reflected from the dusty shells around it. (By the way, the cross of light you see coming from the main star and others in the picture is not real -- it is called a "diffraction spike" and is light sneaking around the support structure of one of the mirrors in the Hubble telescope.)

Cepheid variable stars are an important category of stars in astronomy. Their variations allow us to measure their distances and they are a cornerstone of how we know how far away things are in the universe. About 100 years ago, Henrietta Leavitt, a low-paid "computer" working at the Harvard College Observatory found the crucial relationship that allowed Cepheids to be used for this purpose. Even though women were not usually acknowledged for the "behind-the-scenes" work they did at the Observatory, this discovery was so important it was hard to deny her credit.

Playwright Lauren Gunderson has written a play about Henrietta Leavitt called "Silent Sky." It is coming to the Mountain View (CA) Center for the Performing Arts in January and February, for those readers who live in the San Francisco Bay Area. For everyone else, you can see a short excerpt from a previous production at:

Happy new year and may your skies be dark and clear in 2014.

P.S. For more on Henrietta Leavitt and contributions by other women to astronomy, see my resource guide:

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