There is only a star we are pretty sure we ’ve got the correct years for , and that is the Sun . produce that value for every other star , from the very untested to the very old , is a matter of clever modeling that tries to fit stars into a overnice straight mold . And while it works often , it is far from perfect and is ultimately down to how much we have a go at it about the stars . Even when it comes to our ownSun , there is plenty we do not make out .
But the age of stars is an important factor to know , and theoretically it is quite easy to operate out what you need to look for . It ’s in recitation that it becomes difficult .
For most of the life of a star , it will be flux hydrogen , and how long that lasts depends on the mass of the star – but not in an obvious way .
A schematic Hertzsprung–Russell diagram showing where the main sequence and other portions of stars exist in this classification. Image credit: gstraub/Shutterstock.com
monumental starshave more fuel to burn , but they also radiate a draw more free energy . To not collapse on themselves , they need to be fusing a lot more than a star like the Sun , so they will go through said fuel in a much shorter fourth dimension . Smaller stars will alternatively take things more slowly , as they do not have to burn through their fuel as quickly to assert their national equilibrium .
Based on this , you may see there is a practice of law that unite the geezerhood to the the great unwashed of a star . This is a useful way to get to some eccentric of estimation . It is important to know that no matter the size , when a star begins to release energy due to interior atomic fusion of hydrogen , it will belong to a group called the main sequence .
The term comes from the dispersion of these champion on the Hertzsprung – Russell ( HR ) diagram . On the vertical axis is the luminosity of these object , and on the other the vividness index ( or temperature , or stellar classification ) . The gloomy - bloodless mavin are the with child and red-hot , in the top left , and there d dwarfsare in the bottom right . The Sun is somewhere in the midsection . When stars move off the main sequence they become cherry-red giants ( and then supergiants ) , so their brightness level tends to stay the same but their color changes . All this can be utilitarian when it comes to estimating their ages .
If you have a radical of stars in a cluster , they likely formed at close to the same time as each other . You will have a larger bit of minuscule stars than big unity , but at twelvemonth zero you would expect to have them all in the main chronological succession .
Now , if you go and check on them a certain metre later , a certain number of them will have act off the master sequence . By plot them on the hour diagram you could find theturnoff stop . If in this cluster that point was a star like the Sun , you ’d guess that the bunch is about 10 billion age old , since that ’s how long the Sun is expected to detain on the main chronological succession .
Obviously , this approach shot would not be useful if you had an individual star . To adjudicate and gain some idea , another proficiency can be helpful : asteroseismology . Thisapproachlooks at the oscillations within the stars to gain insights . maven turn hydrogen into He , so an older star is going to have more atomic number 2 and good waving will circularise differently . And from that , age can be assumed .
There are also method that front at therotation of a star , and from that infer an age . This appear to work for the low - mickle main succession stars . For wizard too young to be in the principal sequence , it is potential to guess an old age base on the comportment of material around them , or their variance before they square off into a “ calmer ” main sequence phase .
These method directly or indirectly bank on what we know of the Sun . The more we determine about our little yellowish star , the better we will understand all the stars in the Universe .
