Question

question 13
stars with low mass and low luminosity are less common than stars with high mass and high luminosity.
true
false

question 14
stars that appear brightest to our eyes are bright primarily because they are intrinsically very luminous, not because they are the closest to us.
true
false

question 15
luminosity is:
the measure of the distance of a star from earth.
the measure of the temperature of a star.
the total energy emitted per second by a star.
dependent on both its luminosity and its distance from earth.

Explanation:

Analyze Question 13

This question asks whether low-mass, low-luminosity stars (red dwarfs) are less common than high-mass, high-luminosity stars. According to stellar demographics and the initial mass function, low-mass stars are by far the most common type of stars in the universe, making up the vast majority of the stellar population. High-mass, highly luminous stars are extremely rare. Therefore, the statement is false.

Analyze Question 14

This question states that the stars appearing brightest to our eyes are bright primarily because they are intrinsically very luminous, rather than because they are the closest to us. In astronomy, this is a well-known observational selection effect (the Malmquist bias). Most of the brightest stars in the night sky (like Rigel, Betelgeuse, and Deneb) are highly luminous giant or supergiant stars located hundreds or thousands of light-years away, rather than the very closest stars (which are mostly dim red dwarfs like Proxima Centauri, invisible to the naked eye). Therefore, the statement is true.

Analyze Question 15

This question asks for the definition of luminosity. Luminosity is an intrinsic property of a star, defined as the total amount of electromagnetic energy emitted per unit of time (usually measured in watts or in terms of solar luminosities, \(L_{\odot}\)).

• Option 1 (distance) is incorrect.
• Option 2 (temperature) is incorrect.
• Option 3 (total energy emitted per second) is correct.
• Option 4 is incorrect because intrinsic luminosity does not depend on distance from Earth.

Answer:

Question 13

• True
• False (Correct answer)

Question 14

• True (Correct answer)
• False

Question 15

• The measure of the distance of a star from Earth.
• The measure of the temperature of a star.
• The total energy emitted per second by a star. (Correct answer)
• Dependent on both its luminosity and its distance from Earth.