Kirchoff's Law - Emittance & P-Cygni Profiles

• mark726
In summary, the person is new and has a question about Kirchoff's law. They are unsure of what emmissivity or emittance is. They also have a question about P-Cygni profiles for supernovae and are looking for resources to help with their research.

mark726

Hello,

I'm new here, but I have a question regarding Kirchoff's law (I think its Kirchoff's law, but I'm not sure). I'm looking at it now, and it says that E=M/Msub b. I know that the equation gives the emittance of an object, but I don't know what emmissivity or emittance is! Any help would be greatly appreciated.

Also, what's a P-Cygni profile for supernovae? I'm doing some research into supernova light curves, and from what I've found, Type II-P supernova have P-Cygni profiles, but the only sites I've found either too complex or too simple for what I need. Again, any help would be appreciated!

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Thanks a lot. They do help.

What is Kirchoff's Law?

Kirchoff's Law is a fundamental principle in physics that describes the behavior of thermal radiation emitted by a body in thermal equilibrium.

What is emittance?

Emittance is a measure of the ability of a body to emit thermal radiation. It is defined as the ratio of the radiation emitted by a body to that emitted by a perfect blackbody at the same temperature.

What is a P-Cygni profile?

A P-Cygni profile is a spectral line profile that is characterized by a strong emission component (P) and a weaker absorption component (Cygni). It is often observed in the spectra of stars and other astronomical objects.

How are Kirchoff's Law and emittance related?

Kirchoff's Law states that the emittance of a body is equal to its absorptance at thermal equilibrium. This means that a body that is a good emitter of thermal radiation is also a good absorber of thermal radiation.

How can P-Cygni profiles be used in astronomical research?

P-Cygni profiles can provide valuable information about the physical properties of astronomical objects, such as their temperature, velocity, and composition. They are often used to study the dynamics of stellar winds and the formation of stars and galaxies.