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No. 49: Jan-Feb 1987

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Enormous Stellar Shell Raises Theoretical Questions

"Stars tend to lose material to the space that surrounds them. Some of this loss is gradual and continuous -- the so-called stellar winds. Some is abrupt -- the sudden blowing off of a surface layer that then forms a shell around the star. A group of astronomers now reports in the Nov. 15 Astrophysical Journal the discovery of an especially large, cool shell around the star R Coronae Borealis. How this shell was formed and what makes it glow are both mysteries for which current theory does not seem to have answers."

The newly discovered shell is 26 light-years across, roughly 20 times larger than previously discovered shells. If our sun were in the center, the shell would encompass the nearest 50 stars! The usual stellar shells glow as they absorb and reemit radiation from their parent stars, but the R Coronae Borealis shell, given its distance from its star, cannot be explained in this way.

(Thomsen, D.E.; "Enormous Stellar Shell Raises Theoretical Questions," Science News, 130:333, 1986.)

From Science Frontiers #49, JAN-FEB 1987. 1987-2000 William R. Corliss