As a white dwarf evolves, the direction of its motion on the Hertzsprung-Russell diagram below the main sequence is upper right to lower left, which means that:

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As a white dwarf evolves, it is cooling and becoming less luminous, meaning it is moving lower and to the right on the Hertzsprung-Russell diagram. However, its size or radius remains constant during this process. Therefore, the direction of its motion on the diagram is from upper right to lower left. This is due to the decrease in temperature and luminosity, but with a constant size. Choice A is incorrect because the size of the white dwarf is not increasing. Choice B is also incorrect because while gravitational energy may be released during the shrinking process, it does not necessarily mean the star will die as a hot but very small star. Choice D is incorrect because a white dwarf does not shrink into a cold neutron star.

As a White Dwarf Evolves, the Direction of Its Motion