Which Kind of Stars Are the Major Source of Energy

question 34

Multiple Choice

Which kind of stars are the major source of energy for the heating of the dust clouds and the H II emission nebulae within the planes of the Milky Way and other galaxies?

• A) Hot,young O and B stars,via their UV radiation
• B) The numerous old,red-giant K and M stars,via their IR heat radiation
• C) Very hot white dwarf stars,the remnants of planetary nebulae in the gas clouds
• D) The very many nova and supernova explosions of stars within the gas and dust clouds

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Definitions:

Optic Disk

The point in the back of the eye where the optic nerve connects to the retina, devoid of photoreceptors.

Visual Fields

The total area in which objects can be seen in the peripheral vision while the eye is focused on a central point.

Optic Nerve

The nerve that transmits visual information from the retina to the brain.

Lens

A transparent structure in the eye that focuses light onto the retina to create clear images.