Question

Compared to the central regions of spiral galaxies, we expect elliptical galaxies to have

A) higher mass-to-light ratios because stars in elliptical galaxies are dimmer than those in spirals.
B) lower mass-to-light ratios because stars in elliptical galaxies are dimmer than those in spirals.
C) higher mass-to-light ratios because stars in elliptical galaxies do not have high orbital velocities.
D) lower mass-to-light ratios because elliptical galaxies have less gas and dust than spirals.
E) the same mass-to-light ratio because they are made of the same material, stars and dark matter

Answer 1

Elliptical galaxies have higher mass-to-light ratios compared to spiral galaxies. This is because elliptical galaxies contain older, less luminous stars and may have dark matter contributing to mass without adding much light.

Step-by-step explanation:

Compared to the central regions of spiral galaxies, we expect elliptical galaxies to have higher mass-to-light ratios because stars in elliptical galaxies are dimmer than those in spirals. The stars in elliptical galaxies are typically older with little or no ongoing star formation and turn most of their interstellar matter into stars billions of years ago, which adds to a higher ratio of mass relative to light.

Furthermore, elliptical galaxies do not have a systematic rotation like spiral galaxies, making it difficult to estimate the amount of dark matter they contain based on rotational velocity. Hence, they might possess dark matter that contributes to mass without significantly increasing luminosity.