15 Questions
What is the difference between brightness and luminosity?
Brightness depends on the distance from a star, whereas luminosity does not.
What is the unit of distance used for calculations in astronomy?
Parsec (pc)
What formula is used to find the absolute visual magnitude of a star?
msubv-Msubv=-5+5log(d)
What does the little 'v' in 'msubv' and 'Msubv' stand for?
Visible
What does luminosity refer to?
The total energy a star radiates in one second.
What is the intrinsic brightness of a star sometimes referred to as?
Absolute visual magnitude
What does the apparent visual magnitude of a star tell you?
How bright a star appears to be as viewed from Earth.
What corrections might astronomers need to make when calculating the true luminosity of a star?
To account for invisible forms of energy, like infrared and ultraviolet light.
What does luminosity refer to?
The total energy a star radiates in one second
What is the apparent brightness of a star?
How bright a star appears to us on Earth
How is luminosity different from apparent brightness?
Luminosity is the intrinsic brightness of a star, while apparent brightness is how bright a star appears from far away
What is the technical definition of luminosity?
The intrinsic brightness of a star
How does the text explain the difference between luminosity and apparent brightness?
By using the analogy of a large handheld flashlight
What is the property of brightness of a flashlight similar to, according to the text?
Apparent brightness of stars
What is the difference between the brightness of the flashlight in the garage and its apparent brightness from far away?
The brightness is smaller from far away
Study Notes
Brightness vs Luminosity
- Brightness refers to the amount of light an object appears to emit or reflect, as seen from a particular distance.
- Luminosity, on the other hand, is the total amount of energy emitted by an object per unit time.
- In astronomy, the unit of distance used for calculations is the parsec (pc).
Calculating Absolute Visual Magnitude
- The formula to find the absolute visual magnitude of a star is Mv = m - 5 + 5log(d), where Mv is the absolute visual magnitude, m is the apparent visual magnitude, and d is the distance in parsecs.
Notations and Meanings
- The little 'v' in 'msubv' and 'Msubv' stands for visual, indicating that the magnitude is measured in the visual spectrum.
- Luminosity refers to the intrinsic brightness of a star, or the amount of energy it emits per unit time.
- The intrinsic brightness of a star is sometimes referred to as its absolute magnitude.
Apparent Visual Magnitude
- The apparent visual magnitude of a star tells you how bright it appears to be from a particular distance.
Corrections for True Luminosity
- Astronomers may need to make corrections for interstellar absorption, extinction, and other factors when calculating the true luminosity of a star.
Distinction between Luminosity and Apparent Brightness
- Luminosity is the total energy emitted by an object, while apparent brightness is the amount of light that reaches an observer from a particular distance.
- The technical definition of luminosity is the amount of energy emitted per unit time.
- The text explains the difference between luminosity and apparent brightness by comparing the brightness of a flashlight in a garage to its apparent brightness from far away.
Test Your Knowledge of Relative Brightness with this Fun Quiz! Explore the concept of relative brightness and see how well you understand it. From large flashlights to neighborhood lighting, this quiz will illuminate your understanding of brightness.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
