What Is the Difference Between Flux and Intensity in Astronomy?

In summary, the difference between flux and intensity in astronomy is that flux refers to the total brightness of an object, while intensity refers to its brightness at a specific position. Flux is defined as power per unit area, while intensity is defined as power per unit area per unit solid angle.
  • #1
orange
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Hey everyone!

What is really the difference between flux and intensity in astronomy? What I understand they are two different words of the same thing, namely energy per square length unit per time unit.

I appreciate any help, thanks alot!
 
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  • #2
orange said:
What is really the difference between flux and intensity in astronomy? What I understand they are two different words of the same thing, namely energy per square length unit per time unit.

There are numerous conventions, but most of the ones I see define flux simply as power per unit area, while intensity is power per unit area per unit solid angle. The conceptual difference is that the flux is total brightness of an object, while intensity defines its brightness at a given position (for example, the projected center of a galaxy).
 

FAQ: What Is the Difference Between Flux and Intensity in Astronomy?

1. What is flux and intensity in astronomy?

Flux refers to the amount of energy that passes through a unit area in a given time. In astronomy, it is often used to measure the amount of energy emitted by a celestial object. Intensity, on the other hand, is a measure of the brightness or luminosity of an object. It takes into account the distance of the object and is often used to compare the brightness of different objects.

2. How are flux and intensity related?

Flux and intensity are directly related to each other. As the flux of an object increases, its intensity also increases. This is because the more energy that is emitted by an object, the brighter it appears to us. However, intensity also takes into account the distance of the object, so two objects with the same flux may have different intensities if they are at different distances.

3. What is the difference between apparent and absolute flux/intensity?

Apparent flux and intensity refer to the measurements we observe from Earth. This takes into account the distance of the object and any effects from the Earth's atmosphere. Absolute flux and intensity, on the other hand, refer to the intrinsic properties of the object, independent of our observation. It does not take into account the distance or atmospheric effects.

4. How do astronomers use flux and intensity to study celestial objects?

Astronomers use flux and intensity measurements to study the properties and behavior of celestial objects. By measuring the flux and intensity of an object, they can determine its luminosity, temperature, and composition. They can also compare the flux and intensity of different objects to understand their relative brightness and energy output.

5. Can flux and intensity measurements be used to determine the distance of an object?

Yes, flux and intensity measurements can be used to estimate the distance of an object. By comparing the apparent flux and intensity of an object to its absolute values, astronomers can calculate the distance using the inverse square law. However, other methods such as parallax and redshift are often used for more accurate distance measurements.

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