Use of Standard Candles in Measuring Distances in Astronomy

[MatinSAR]

TL;DR Summary: I need to understand their definition.

In a refrence I've read :
One of the basic missions of Astronomy is to measure distances in the cosmos. This is usually done using the method of standard candles, which requires identifying astronomical objects or phenomena with a repeatable luminosity, and to measure that luminosity.

Could I describe a standard candle as a celestial object with known luminosity? Even if its luminosity varies over time, we understand how it changes. Am I right?

 

[Ibix]

I would keep in mind that it's a chain of observations standing one atop another, so I'd tend to go with things where we believe we know the luminosity. But basically, yes you are correct. Since we can measure the amount of light we receive from each one and we believe we know how much light they emit, we can use the ratio to calculate the luminosity distance.

 

[MatinSAR]

@Ibix Thank you.

 

[MatinSAR]

Hi everyone,
I'm currently preparing a presentation on the use of standard candles for measuring distances in astronomy. I'm looking for some references that can help deepen my understanding of this topic. Could you please recommend any books, papers, or articles that you found useful?
I'm looking for undergraduate-level references, so I prefer not to have highly specialized sources.
Thank you for your assistance!

 

[DaveC426913]

Even if its luminosity varies over time,

You mean like Cepheid Variables?

 

[MatinSAR]

You mean like Cepheid Variables?

Yes.

 

[MatinSAR]

One more question.

which requires identifying astronomical objects or phenomena with a repeatable luminosity, and to measure that luminosity.

By "repeatable luminosity," we mean that an object's luminosity can be inferred by comparing it to other similar objects with known luminosities, for example, those with similar spectral characteristics. Am I right?
e.g. when we use stars as a standard candle ...

 

[DaveC426913]

One more question.

By "repeatable luminosity," we mean that an object's luminosity can be inferred by comparing it to other similar objects with known luminosities, for example, those with similar spectral characteristics. Am I right?
e.g. when we use stars as a standard candle ...

But how do you know they are "similar objects"?

Is having "similar spectral characteristics" sufficient to infer that they have similar luminosities? And to what degree of confidence?

The reason Cepheid Variables are useful is because we have an independent way (independent of their apparent mag) of judging their absolute magnitude.

 

[MatinSAR]

But how do you know they are "similar objects"?

Is having "similar spectral characteristics" sufficient to infer that they have similar luminosities? And to what degree of confidence?

That's what I'm trying to find out. I was questioning what they meant by "repeatable luminosity," and that similar spectral characteristics was my guess. So I don't know the answer to your question.

 

[DaveC426913]

That's what I'm trying to find out. I was questioning what they meant by "repeatable luminosity," and that similar spectral characteristics was my guess. So I don't know the answer to your question.

Oh right. This is from a reference. Can you quote from the reference?

 

[MatinSAR]

Oh right. This is from a reference. Can you quote from the reference?

Sure.

Picture from Astronomy at the Frontiers of Science.