Counting a star's birthday candels


There are many ways to count the candles on the star's birthday cake to star clusters that are in the western evening sky at this time of year provides two examples messy eight thirty four is in the constellation Perseus it's about halfway up the sky in the west northwest at nightfall well to the upper right of Venus the evening star and messy eight thirty six is higher in the sky in a raga it's to the left of the yellow orange star capella M. thirty six is the younger of the two clusters less than twenty five million years old one way astronomers came up with that number is by measuring lithium in a specially small cool stars stars begin life with just a smattering of lithium and it's quickly destroyed by the stars nuclear reactions more massive stars burn through their lithium faster than less massive stars so by measuring the amount of the element in stars of different weights they can come up with an estimate of a clusters H. in this case about twenty two million years astronomers you stars at the opposite end of the eight scale to measure the age of M. thirty four they used quite towards the small dead cores of once normal stars stars of different masses burn out at different times with heavier stars going first and they leave white dwarfs that have different mixtures of chemical elements for the white dwarfs in M. thirty four indicate an age of about two hundred twenty five million years a good match to the other techniques used to count the stars birthday candles we have much more

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