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Astrophysics and Cosmology

The solar system and the birth of a star

  • 5 things to know
  • Papers 1, 2 and 3

Overview

Recall questions on solar systems, planets, planetary satellites, comets, galaxies and the universe, and how a star forms from an interstellar cloud through gravitational collapse, fusion and the balance of radiation and gas pressure.

What you need to know

Answer each one before you reveal it.

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Process

As a protostar becomes a main sequence star, what nuclear reaction begins, how does radiation pressure arise, and what balance must be achieved?

Key term

What constitutes a solar system?

Key term

Define a galaxy.

Key term

What is a planetary satellite?

Key term

What energy transformation occurs as a protostellar cloud collapses, and what effect does this have?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What constitutes a solar system?

    Model answer

    A solar system consists of a star together with all the planets, moons, asteroids, comets and other objects gravitationally bound to it.

  2. 2

    Define a galaxy.

    Model answer

    A galaxy is a large system of stars, gas, dust and dark matter held together by gravity, typically containing billions of stars.

  3. 3

    What is meant by the universe?

    Model answer

    The universe is the totality of all space, time, matter and energy, encompassing all galaxies and the space between them.

  4. 4

    What materials are present in the interstellar cloud from which stars form?

    Model answer

    The interstellar cloud contains hydrogen and helium gas plus dust.

  5. 5

    What causes an interstellar cloud to begin collapsing during star formation?

    Model answer

    Gravitational attraction between particles in the cloud causes it to collapse.

  6. 6

    Why does the collapse of a star-forming cloud accelerate over time?

    Model answer

    As the cloud collapses, its density increases, which strengthens gravitational attraction and accelerates the collapse further.

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A wave.
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AForce is a vector quantity.
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Density means mass per unit volume.
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