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The Question
(Submitted April 22, 2006)
How does the discovery of Polaris being a binary star affect our thoughts
on cepheid variable stars, and how will it help us discover more about the
size and growth of our universe?
The Answer
Thanks for your question. Polaris is believed to be a special
type of Cepheid in which it is pulsating at its first overtone mode with
more than one node of pulsation within the star. Since Polaris has
companion stars, the minute changes in Polaris' orbit caused by the
interaction with the companion stars gives a measure of the mass of
Polaris --which can be used independently to better understand the
physics of Cepheid behavior of Polaris. You might want to read more
at the following website:
http://www.astro.uiuc.edu/~kaler/sow/polaris.html
Understanding Cepheids in better detail will help to better
delineate Cepheids as Standard Candles, ie, objects in space that can
be used to measure distances and knowing distance scales better will
help us to understand how the universe is growing. You can read about
the distance ladder at:
http://heasarc.gsfc.nasa.gov/docs/cosmic/
Hope this helps,
Georgia & Mike
For "Ask an Astrophysicist"
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