ASTR online reading quiz 7
Who ``pays the bill'' for the energy generated by nuclear fusion in the Sun? In other words, from where does all of the energy pouring out of the Sun ultimately come?
A little bit of mass is lost in each nuclear reaction, and is turned into energy that is, the Sun is (slowly) losing mass!
Roughly how long does it take for the energy from photons created by hydrogen fusion at the center of the Sun to reach the surface of the Sun?
About 1,000,000 years
Which of the following statements about the life of a star with a mass equal to that of our Sun is correct?
As the star is dying, a considerable amount of its mass will be lost into space
The Sun is an enormous ball of gas. Left to itself, a ball of so many gas atoms should collapse under its own tremendous gravity. Why is our Sun not collapsing?
Nuclear fusion in the core keeps the temperature high, and the resulting gas pressure and radiation pressure inside the Sun exactly balance gravity
In what part of the sun is the fusion of hydrogen occuring today?
Only in the central, "core" regions of the sun
According to the Einstein's famous formula E = mc^2
a little bit of mass can be converted into a substantial quantity of energy
Many names used by astronomers are misleading or outdated. A good example is the term planetary nebula, which astronomers use to refer to:
a shell of gas ejected by, and expanding away from, an extremely hot lowmass star that is nearing the end of its life
Interstellar gas consists primarily of
hydrogen
When four hydrogen nuclei fuse to form a helium nucleus through the "protonproton chain", the mass of the resulting helium nucleus:
is about 0.7% less than the sum of the masses of the four hydrogen nuclei
When a positron and an electron collide, they produce:
pure energy in the form of a photon
