Biology Forums - Study Force

Once hydrogen is exhausted in the core of a main sequence star?
the helim "ash" in the core expands due to its great heat making a red giant

the helium "ash" immediately ignites to make a red giant
the helium "ash" in the core contracts and heats up until helium burning
the carbon "ash" in the core contracts to make a white dwarf
the helium "ash" in the core contracts and cools off to make a neutrons star

absolutely no-one knows , what is presented as fact is all guesswork and conjecture, we have had reasonable telescopes for 60 years the stars have been around for 15 billion years and many that we think we can see today are no longer there because of the time the light has taken to reach us, to presume that all stars go through exactly the same processes is naive and not FACT

Harley Drive's response is a perfect example of why you shouldn't just ask for a flat-out answer without volunteering your own best educated guess and why you think it is correct. Then when we either confirm or correct you something may be learned.

As it is, just asking for an answer gives you high odds that your teacher will mark your response "incorrect". As an anonymous source (even mine) for answers really has no weight as far as your teacher goes.

It's actually a rather smooth transition within the star.  The helium will remain in the core as ash until a certain point when the mass of helium is significantly greater than the mass of hydrogen.  At this point, the more dense helium will cause the core to contract.  It contracts to the point of helium ignition, which then causes the star to heat up and expand, entering the red giant phase of life.  So, there is a point in time when you have hydrogen fusion and helium fusion occurring at the same time.