Why Is There a Limited Range of Stellar Surface Temperatures

question 66

Multiple Choice

Why is there a limited range of stellar surface temperatures around 10,000 K at which neutral hydrogen gas absorbs visible light in the Balmer series?

• A) There must be electrons at the n = 3 energy level for Balmer absorption to occur. If the gas is too cold, electrons are only in the n = 1 and 2 levels; if the gas is too hot, the gas is ionized and no electrons are left in the hydrogen atoms.
• B) Electrons in hydrogen have to be at the n = 2 energy level to produce absorption in this series. If the gas is too cold, most atoms are in the n = 1 state; if it is too hot, most atoms are ionized.
• C) Electrons must be in the ground state n = 1 to undergo Balmer absorption. If the gas is too cold, electrons cannot be excited from this level; if the gas is too hot, there are no electrons left in the n = 1 level.
• D) There must be sufficient continuum radiation from the stellar surface in the visible region to be absorbed by the hydrogen gas.

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Definitions:

Cardiac Output

The volume of blood the heart pumps through the circulatory system in one minute, a critical measure of heart function and efficiency.

Stroke Volume

The amount of blood the heart ejects with each beat, a key component in determining cardiac output.

Venous Return

Volume of blood returning to the heart.

Stroke Volume

The amount of blood ejected by the left ventricle of the heart in one contraction.