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Questions and Answers
If two stars have the same apparent magnitude, but Star A is twice as far away as Star B, how do their absolute magnitudes compare?
If two stars have the same apparent magnitude, but Star A is twice as far away as Star B, how do their absolute magnitudes compare?
- Star A's absolute magnitude is fainter than Star B's.
- The relationship between their absolute magnitudes cannot be determined without knowing their temperatures.
- Star A and Star B have the same absolute magnitude.
- Star A's absolute magnitude is brighter than Star B's. (correct)
A star's color is most directly related to its surface temperature. Given this, which of the following stars would have the shortest peak wavelength of emission?
A star's color is most directly related to its surface temperature. Given this, which of the following stars would have the shortest peak wavelength of emission?
- A yellow star with a surface temperature of 5,500°C.
- A white star with a surface temperature of 10,000°C.
- A blue star with a surface temperature of 30,000°C. (correct)
- A red star with a surface temperature of 3,500°C.
Which of the following statements best describes the relationship between a star's luminosity, size, and temperature?
Which of the following statements best describes the relationship between a star's luminosity, size, and temperature?
- Luminosity is directly proportional to the square of the size and directly proportional to the fourth power of the temperature. (correct)
- Luminosity is inversely proportional to size and directly proportional to the fourth power of the temperature.
- Luminosity is directly proportional to the square of the size and directly proportional to the temperature.
- Luminosity is directly proportional to size and inversely proportional to the square of the temperature.
Two stars have the same temperature. Star X has a larger absolute magnitude than Star Y. Which of the following conclusions can be drawn about their sizes?
Two stars have the same temperature. Star X has a larger absolute magnitude than Star Y. Which of the following conclusions can be drawn about their sizes?
Why do astronomers use absolute magnitude rather than apparent magnitude to classify stars?
Why do astronomers use absolute magnitude rather than apparent magnitude to classify stars?
Flashcards
What are stars?
What are stars?
Massive, glowing spheres of hot gas (mostly hydrogen and helium) that produce light and energy through nuclear fusion.
What is apparent magnitude?
What is apparent magnitude?
How bright a star appears from Earth.
What is absolute magnitude?
What is absolute magnitude?
The actual brightness of a star at a standard distance of 32.6 light-years.
What does a star's color indicate?
What does a star's color indicate?
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How does a star's size relate to its brightness?
How does a star's size relate to its brightness?
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Study Notes
- Stars are massive, glowing spheres of hot gas, mainly hydrogen and helium.
- Stars produce light and energy through nuclear fusion.
Brightness of Stars
- Indicates its size: larger stars have more luminosity.
- Apparent Magnitude: A star's brightness as seen from Earth.
- Absolute Magnitude: A star's actual brightness measured at 32.6 light-years.
Color of Stars
- Indicates surface temperature: hotter stars appear bluer, while cooler stars appear redder.
- Blue stars have a surface temperature greater than 25,000°C (e.g., Rigel) and are the hottest.
- White stars have a surface temperature of about 10,000°C (e.g., Sirius).
- Yellow stars have a surface temperature of about 5,500°C (e.g., the Sun).
- Orange stars have a surface temperature of about 4000°C (e.g., Aldebaran).
- Red stars have a surface temperature less than 3,500°C (e.g., Betelgeuse) and are the coolest.
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Description
Stars are glowing spheres of gas that produce light through nuclear fusion. A star's brightness indicates its size, with larger stars having more luminosity. Color indicates surface temperature, ranging from blue (hot) to red (cool).
