Importance of a standard candle?

[NanaToru]

So I'm a little confused about what a standard candle tells us exactly. From what I understand, it means that the luminosity is relatively constant. Does this tell me something about apparent or absolute magnitudes? Like if a supernova has a peak brightness of an apparent magnitude of 0.7, does this mean that luminosity is 0.7? I am thoroughly confused.

 

[jedishrfu]

Here's an article that may help:

http://en.wikipedia.org/wiki/Standard_candle

Its basically an object that we can identify with a known luminosity and using that can determine how far it is from us.

 

[NanaToru]

haha should have expected that.

I wasn't sure if it implied anything else other than a new way to find distance, but it was in relation to another question that I figured out, subsequently helping with this.

thank you!

 

[Astrofan]

haha should have expected that.

I wasn't sure if it implied anything else other than a new way to find distance, but it was in relation to another question that I figured out, subsequently helping with this.

thank you!

Well, finding distances is already a very BIG deal! Knowing how far stuff is happening from us has helped us map out the structure of the universe for instance. Other than that, without knowing the distance from events, the dimensions of objects on the sky are basically physically meaningless numbers! (Just like knowing that the Sun is half a degree doesn't tell you anything about how large the Sun actually is until you work out the distance)
Measurements of distances using means like paralax are limited to a small range.
For longer ranges standard candles have to be used. The continual search for better and more accurate standard candles cam enable the probe of even earlier phases of the universe.

 

[pmacias]

A standard candle is an astronomical object with a known and consistent luminosity, which can be used as a reference point for measuring distances in the universe. This is because the apparent brightness of an object decreases with distance, but its intrinsic luminosity remains the same. By comparing the apparent brightness of a standard candle to its known intrinsic luminosity, scientists can calculate the distance to the object.

The use of standard candles is crucial in determining the scale of the universe and understanding its expansion. By measuring the distances to objects at different points in the universe, scientists can create a three-dimensional map of the universe and track its evolution over time.

To answer your question, the apparent magnitude of an object is a measure of its brightness as seen from Earth, while the absolute magnitude is a measure of its intrinsic luminosity. So, a supernova with an apparent magnitude of 0.7 does not necessarily have a luminosity of 0.7, as its intrinsic luminosity may be much higher. However, by using standard candles with known absolute magnitudes, scientists can accurately determine the absolute magnitudes of other objects and use them to calculate distances.

In summary, the importance of a standard candle lies in its consistent and known luminosity, which allows scientists to accurately measure distances in the vastness of the universe. Without the use of standard candles, our understanding of the scale and evolution of the universe would be limited.