Standard Candles, Luminosity and Radiant Flux Intensity

What is luminosity?

• Luminosity is the distance between two stars.
• Luminosity is the total power of radiation emitted by a star.

• Luminosity refers to the color of an astronomical object.
• Luminosity is the brightness of a star as seen from Earth.

What is radiant flux intensity?

• Radiant flux intensity is the total energy emitted over time.
• Radiant flux intensity measures the temperature of a light source.
• Radiant flux intensity is the color of the emitted radiation.
• Radiant flux intensity is the observed intensity of radiation.

A student made three suggestions on why some stars appear brighter then others in the night sky:

1. 1.Brighter stars could be closer to Earth

2. 2.Brighter stars could have a greater luminosity

3. 3.Brighter stars could be larger in size

Which of the suggestions above are true?

• 1 and 2 only

• 2 and 3 only

• 1 and 3 only

• all of the above

What are standard candles?

• Standard candles are used to measure temperature in stars.
• Standard candles are a type of celestial event that occurs in supernovae.
• Standard candles are objects used in astronomy to measure distances based on their known luminosity.
• Standard candles are tools for measuring the brightness of planets.

How are standard candles used to determine distances to galaxies?

• By using a telescope

• By using a distance-o-meter

• By applying the radiant flux intensity (F) equation, where F is measured by the observer, and using the known luminosity of a standard candle.

• By applying the Luminosity equation and comparing luminosity of stars to their distances