Astronomy Cast

Ep: 108: The Life of The Sun (9/30/2008)


4.6 billion years ago+  Cold cloud of gas&dust- somehow caused to contract into a bunch of baby stars
Sun started out 10 times brighter as it is right now, sun got fainter as it contracted
then started nuclear burning in its core
during early parts of sun's life- very violent and active, powerful magnetic fields, flares
Sun settles down to main sequence (hotter in the past then today) 
Overtime our sun is heating up again (very gradual process, billions of years) 
the sun will stay a main sequence star for another 5 billion years 


About 5 billion years from now we start to run out of Hydrogen that is readily available for fusing in the center of the Sun.  When this happens the Sun is going to start contracting because there is not going to be as much pressure from the light supporting the outer layers of the Star.


in tiny stars, the burning process is able to create what we call convective mixing.  The entire Star essentially acts like a Lava Lamp, it’s able to constantly refuel the center of the Star.  


In a magical moment when it reaches a temperature ten to the 8 degrees, suddenly the Helium in the center of the Sun is able to ignite.  We call this a Helium Flash.  At this point the Sun becomes what we call a Horizontal Branch Star.


This is part of why so many of the really bright Stars that we see in the Sky are these red Stars.  We can just see red Stars at a much greater distance and this is a common phase for Stars to go through.  


We refer to the Main Sequence as the majority of the Star’s life and that’s exactly what it is.  Then it goes off and does all these really cool things but those happen essentially in the blink of a Cosmic eye.  Once the Star hits the Mira phase, just maybe four or five hundred million years after leaving the Main Sequence, at that point it starts losing its Atmosphere.

It starts transitioning from being a Star that’s burning and doing all the Star-like things to blasting its Atmosphere away starting to form a Planetary Nebula.  A Planetary Nebula is nothing more than the Atmosphere of a Star that’s been exhaled and hasn’t yet drifted so far away from its starting point that we can no longer see all the gas associated with one another.


I really like this astro cast! Hearing so much in depth about the sun clarifies many things and yet confuses me (so much info!) at the same time!