We Find That Interstellar Gas and the Youngest Disk Stars

question 94

Multiple Choice

We find that interstellar gas and the youngest disk stars are found in a very narrow distribution along the galactic plane, but that older disk stars can be found in a thicker disk. What might this mean?

• A) Gravitational scattering off molecular clouds changes the orbits of disk stars as they get older.
• B) The disk is still settling down from a thicker to a thinner state.
• C) The galaxy has not absorbed any dwarf galaxies in the last several billion years.
• D) Cosmic rays are responsible for causing star formation to happen in a narrow layer over time.
• E) Most of the dark matter in the galaxy is in a thin layer along the disk.

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Definitions:

Carbon Fixation

The process by which inorganic carbon (usually in the form of CO2) is converted to organic compounds by living organisms, prominently through photosynthesis in plants.

Photosynthetic Organisms

Organisms that are capable of photosynthesis, a process of converting light energy into chemical energy, primarily occurring in plants, algae, and certain bacteria.

Decomposers

Organisms, such as bacteria and fungi, that break down dead organic matter, recycling nutrients back into the ecosystem.

Biogeochemical Cycles

The cycles that involve the movement and transformation of chemicals and elements through biological organisms, geological processes, and chemical processes within ecosystems.