Exam 24: Stars, Space, and Galaxies

A pulsar is a ____ that emits a pulsating radio signal.

Explain what will happen to the Sun in five billion years from now.

Five billion years from now, the hydrogen in our Sun's core will be exhausted and the Sun will expand into a red giant.

___ are short-lived releases of high-energy radiation emanating the death throes of massive stars, when a neutron star is sucked into a black hole, or when two neutron stars collide to form a black hole.

The mass of our galaxy calculated from its rotational speed is much larger than the mass of all the known matter within. Astronomers have proposed that ____________________ may provide the additional mass to explain this difference.

Describe the Hertzsprung-Russell diagram.

Main sequence stars fall along a sinuous diagonal band across the Hertzsprung-Russell diagram.

The way a star will end its life depends on its ____.

Describe the photosphere.

Before the Universe cooled enough for atoms to exist, about 300,000 years after the big bang, the Universe was fog-like or opaque because photons could never move far in any direction without being absorbed.

The Universe was perfectly homogeneous, or uniform, in its infancy.

One ____________________ is the distance traveled by light in a year, or 9.5 trillion kilometers.

The Sun is a population II star.

A small, extremely dense star that emits regular, closely spaced radio signals is a(n) ____________________.

Describe a supernova.

What is an elliptical galaxy?

Describe a black hole.

The major reason for differences in temperature and luminosities among main-sequence stars is that some ____.

Jets of gas called ____________________ shoot upward from the chromosphere, looking like flames from a burning log.

Black holes are black because ____.