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Welcome to Idaho Skies for July 12th and 13th. We’re your hosts, Paul...
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...and Rachel.
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Astronomers classify stars based on their spectral characteristics.
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These characteristics, astronomers discovered, are related to a star’s temperature.
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And the factors controlling the surface temperature of a star are its mass and age.
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This means astronomers can determine the mass and age of a star by looking at its spectrum.
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There are seven traditional groups that astronomers use to classify stars.
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The groups are O, B, A, F, G, K, and M.
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You can remember this sequence with the sentence, Oh be a fine girl, kiss me.
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So okay, obviously an old male astronomer created this mnemonic.
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The hottest stars and therefore the most massive are O stars.
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These supergiant stars shine with an intense blue-white light that’s rich in ultraviolet.
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But their mass and intensity means they won’t live very long.
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The coolest stars are the red dwarf stars.
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Red dwarfs have low masses and fuse their hydrogen at just a trickle.
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So they’ll live for over a trillion years in some cases.
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Our sun is a G star, or slightly below average in the classification scale.
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However, there are many more M class stars than there are O class stars.
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Which means the sun is actually larger and hotter than the average star found in the Milky Way galaxy.
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Astronomers have further subdivided their stellar classification scale into ten numbers per class.
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The numbers go from 0 to 9 and on this scale.
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And the sun is a class G2 star on this scale.
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That’s Idaho Skies for the 12th and 13th of July.
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Be sure to follow us on Twitter @IdahoSkies for this week’s event reminders and sky maps.
For Idaho Skies this is Rachel...
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...and Paul.
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Dark skies and bright stars.