Nasa Star Study (Page 2 of 3) in pdf

Stars and Their Fates

The size of the star affects its lifespan. Larger stars live _____________ lives, but the majority of the stars live

for ______________ of years. Nuclear reactions end when a star has fused all the ___________________ in

its core. The core then begins to collapse into itself and grows _____________________. Hydrogen is

available outside the core, so ___________________________ continues in a shell outside of the core. The

outer layers of the star expand and cool which transforms the star into a _____________________________.

White Dwarfs

Average stars, like the Sun, who continue to eject their outer layers until the core is exposed become

_________ _____________. These stars are considered the dimmest in the universe, but they puzzled

scientists for years because their _______ did not support their mass according to traditional thinking.

However, in the 1920s, with the development of ______________ _____________, scientists theorized that

pressure from fast moving ____________ keep these stars from collapsing. With White Dwarfs, the smaller in

diameter it is, the larger it is in ___________________. Our Sun will become a white dwarf in

____________________________ years.

Nova – Supernovan

When a white dwarf is close to another star, its _______________ may drag hydrogen from the outer layers

onto itself to build its surface layer. When this builds up, a ________________________ occurs which causes

the white dwarf to temporarily brighten greatly and expel the remaining material. Then the white dwarf returns

to its previous state so that the cycle can begin again. If the white dwarf is very massive, it may add so much

mass that it collapses and explodes completely which is known as a _______________________.

So how is a Nova and a Supernova different? In a nova, only the star’s __________________ explodes. In a

supernova, the star’s ______________ __________________ and then explodes. On average, about one

supernova explosion in a galaxy occurs every _____________ years.

Neutron Stars

If the collapsing core at the center of a supernova contains between __________ and 3 solar masses, the

collapse continues until _______________ and protons combine to form ____________ which produces a

________________ star. These stars are extremely ______________. With so much mass packed into a

small volume, the ______________________ at the surface is so immense that it would pull a spacecraft to

pieces before reaching the surface. Neutron stars also have powerful ________________ fields which

accelerate atomic particles around its magnetic poles to produce beams of _____________________ that act

like search beams as the star rotates.

Nasa Star Study Page 2