Question

a hertzsprung - russel, or h - r diagram is a diagram that is used to classify stars based on which two characteristics?
shape & number of planets
color & shape
temperature & brightness
question 13 (1 point)
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a ______ is a group of objects such as planets, moons, asteroids, and comets that orbit a star, held together by gravity.
galaxy system
solar system
universe system
moon system

Explanation:

For the first question, the Hertzsprung - Russell (H - R) Diagram is a fundamental tool in astronomy. Stars' surface temperature (related to color) and luminosity (brightness) are key characteristics. Temperature affects a star's color (e.g., blue - hot, red - cool), and luminosity is how bright a star is.
For the second question, the Solar System is defined as the collection of the Sun (the star) and objects like planets (e.g., Earth, Jupiter), moons (e.g., Moon of Earth), asteroids (in the asteroid belt), and comets (e.g., Halley's Comet) that orbit the Sun, held together by the Sun's gravity. A galaxy is a much larger structure with billions of stars, and "Universe System" and "Moon System" are not standard terms for this group of objects.

Answer:

First question: Temperature & Brightness.
Second question: Solar System.