The Cepheid "Standard Candle" is not so Standard After All
Standard candles are astronomical objects that make up the rungs of the so-called cosmic distance ladder, a tool for measuring the distances to farther and farther galaxies. The ladder's first rung consists of pulsating stars called Cepheid variables, or Cepheids for short. Astronomers at Iowa State University and the University of Western Ontario have found the first direct proof that the Cepheid "standard candles" shrink in mass, making them not quite as standard as once thought. The findings, made with NASA's Spitzer Space Telescope, will help astronomers make even more precise measurements of the size, age, and expansion rate of our universe.
Comments:
I have always felt uncomfortable with the standard candle assumption. Although I doubt that distances will be altered significantly by this finding, it further supports my standard candle dysphoria.<img class='' src='http://new.astromart.com/astromart/javascripts/sceditor/emoticons/smile.png' alt='smile' title='smile'/>
My question is simple and basic---Is the term "bow shock" just short for "bow shock wave"?? I thought I remembered slways seeing the word, wave, in there somewhere.<br><br>Dave K.
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