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Science & Mathematics by Anonymous 2018-07-05 03:33:50
Social Science
What does it mean when a star has negative metallicity?
4 answers
According to Wikipedia, Arcturus has a metallicity of -0.52. What does this mean? The margin of error is only 0.04.
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Anonymous
Iridflare has it almost right, but the sun's metallicity is ZERO, because log(1) = 0. I agree the fraction of metals in Arcturus is about 1/3 of that in the sun, because log(1/3) is around -0.48.
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Anonymous
Arcturus is not an actual city, and it is not made of metal. Those are scientific terms.
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Anonymous
What is called "metallicity" is actually the logarithm of the "metal" content, relative to the Sun. Negative metallicity means the star has less metals than the Sun.
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Anonymous
The sun's metallicity is unity (1). A star's metallicity is expressed as the log(10) of <star's metal content> / <sun's metal content>. -.52 means the ratio of metal to hydrogen in Arcturus is about a third of the sun's ratio.
