Astronomy Test 3

The 21-cm radio emission of neutral hydrogen is created when ________.

electrons flip their spin with respect to the proton in the atom.

The merging of atomic particles into larger ones is _________, while the splitting of large ones into small is _________.

fusion, fission

The concept of hydrostatic equilibrium (also known as gravitational equilibrium) is a balance between ______ and _____.

gravity, gas pressure

The core of a dust grain can be described as all except which of the following? surrounded by ices, hydrogen ice, likely partially graphite, likely partially silicate

hydrogen ice

Interstellar gas which is detected in the X-ray light was likely heated to that temperature by _________.

supernovae

The H-R diagram plots the relationship between stellar _______ and ________.

temperature and luminosity

These stars with list colors need to be sorted into increasing temperature. Provide the correct choice for the list. Archenar (blue), Betelgeuse (red), Capella (yellow)

Betelgeuse, Capella, Archenar

The Sun is composed of _____.

Hydrogen and Helium like Jupiter

_________ are gases that have electrons removed from them by extra energy input.

Ionized cloud

What two factors determine how bright a star appears in the sky?

Luminosity and Distance

The spectral classes from hottest to coldest are:

OBAFGKM

The mass of Helium is not equal to the mass of 4 protons. This illustrates _______.

The Sun's ability to convert mass into energy.

We can map the strength and location of magnetic fields on the Sun because of the __________.

Zeeman Effect

Which class of stars emphasize the absorption lines due to hydrogen the most?

`A stars

In the first step of the proton-proton process of nuclear fusion, two protons initially become _______.

a deuterium particle

Spectra class examples appear different because their stars are :

at different temperatures with varying element emphasis

Blue stars are examples of _______ stars.

bright and easily seen but less common

The upper right hand section of the H-R diagram represents ________ stars.

cool, large and luminous

Molecular clouds are cold and therefore best studied in the light range corresponding to ___________.

infrared and radio

When switching to longer infrared wavelengths for our use of camera, dust clouds reveal themselves as _________.

light emitting regions

Stars that are colder in temperature should have a _______ luminosity. If they have a high luminosity it would be due to __________.

low, having a larger radius and therefore more surface area

The gamma-rays produced in the core of the Sun will reach the surface as visible light. The path requires _________ as the time to exit.

many 100 thousand years

Binary stars allow astronomers to directly determine the _________.

mass of stars

High temperatures are required for fusion to occur because _________.

neutrinos interfere with the proton collisions at low temperatures

The following list that illustrates the order of the atmospheric layers of the Sun as listed from closer to interior and moving outward is

photosphere, chromosphere, corona

Gas clouds near hot stars are sometimes red. This is a result of ________.

the hot stars ionizing the hydrogen in the clouds and allowing red emission at the electrons recombine

An example of the solar cycle is ________________.

the increase and decrease of sunspots on a 11-year repeat

90% of stars occupy which region of the H-R diagram

the main sequence

Dust clouds near hot stars look blue because ________.

the particles reflect or scatter blue light