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January 17, 2011

"Standard Candle" Actually Quite Dynamic

Standard Candles or Cepheids illuminate the size of the universe. However, unlike previously thought, Cepheids shrink in mass. Using the Spitzer Telescope, astronomers, with this new knowledge, will be able to "make more precise measurements of the size, age, and expansion rate of our universe."

Cepheids are the foundation for measuring the distances to galaxies. Understanding that Cepheids are not of a constant size can significantly affect the measurements of these distances. In fact, like actual candles, Cepheids deteriorate as they burn.

The star in question is Delta Cephei. Interestingly, some stars pulse with a beat that is related to their brightness. The measurements of how bright the star appears in the sky compared to its intrinsic brightness allows for the distance calculations. But, given the finding that winds from a Cepheid blow off much gas and dust, the brightness of the Cepheid would be shrouded. To put it in perspective, astronomers estimated that the wind of Delta Cephei is up to one million times stronger than the wind blown by our Sun.

For further proof, astronomers followed up with observations of other Cepheids and found that around 25% of the Cepheids are also losing mass.

An article like this goes to show that knowledge of our universe is constantly expanding. With advances in technology, astronomers are able to make discoveries like this. And who knows, a finding in twenty years could disprove this one.

The full article and accompanying images can be found at: http://www.nasa.gov/mission_pages/spitzer/news/spitzercepheids20110112.html

Posted by hartadam at January 17, 2011 02:14 PM


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