What happens to the rotation of a molecular cloud as it collapses to form a star?
The rotation rate increases and results in a disk of material around a protostar
For ever star with a mass greater than 10 solar masses, about how many stars are there with masses less than a solar mass?
What do astronomers mean when they say that we are all "star stuff"?
That the carbon, oxygen, and many elements essential to life were created by nucleosynthesis in stellar cores
What can we learn about a star from a life track on an H-R diagram?
What surface temp. and luminosity it will have at each stage of its life.
What is planetary nebula?
The expanding shell of gas that is no longer gravitationally held to the remnant of a low-mass star.
What is the CNO cycle?
A type of hydrogen fusion that uses carbon, nitrogen, and oxygen atoms as catalysts.
Which element has the lowest mass per nuclear particle and there fore cannot release energy by either fusion or fission?
What happens when the gravity of a massive star is able to overcome neutron dgeneracy pressure?
The core contracts and becomes a black hole.
What types of stars end their lives with supernovae?
stars that are at least several times the mass of the sun.
Suppose the Betelguese (the upper left shoulder of Orion) were to become a supernova tomorrow (as seen here on Earth). What would it look like to the naked eye?
Would remain a dot of light but would suddenly become so bright that, for a few weeks, we'd be able to see it during the day time.
pressure on an atomic level where things are so dense that electrons try to occupy the same space but cannot, creating a pressure. (ex: the people trying to sit in chairs at the same time)
Explain why degeneracy pressure can support a stellar core against gravity even when the core becomes very cold.
When the core becomes cold, the density would increase and push the molecules of the core closer together. Degeneracy pressure will not let this happen b/c no two electrons can occupy the same space which will create a pressure and support itself against gravity.
an object too small to become an ordinary star because electron degeneracy pressure halts its gravity collapse before fusion becomes self-sustaining; brown dwarfs have a mass less than 0.08Msun
What is the minimum mass for a star and why can't objects with lower masses be true stars?
The smallest mass for a star to form is 0.08Msun. Objects with lower masses can't self-sustain fusion and therefore can't really be stars.
What is the max. mass of a star? What kind of pressure limits how massive a star can be?
The max. mass of a star is about 150 times that of our sun. The pressure that limits how massive a star can be is radiation pressure which is when the photons of light exerting a slight pressure when they strike matter causing an outward pressure of the star.
Why is mass so important to a star's life?How and why do we divide stars into groups by mass?
The birth mass determines the fusion progression within the core of the star. We divide these into groups because lower mass stars usually live longer than higher mass stars and they can produce different elements through fusion
When a star exhausts its core hydrogen fuel, the core contracts but the star as a whole expands. Why?
Hydrogen burns around a helium core increasing heat and causing the star to expand.