Jason Tumlinson, J. Michael Shull, Aparna Venkatesan

Cosmological effects of the first stars: evolving spectra of Population III Remigiusz Pospieszynski October 16, 2007

Overview ●

Definitions

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What we DO NOT know

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What we DO know

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What can we do

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The models

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Results

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Conclusions

Population III ?

Population III star (metal-free star) – hypothetical population of masive (10100 Mʘ) and hot stars with virtually no metal content. They are believed to have been formed in the early Universe. The have not been observed. Yet...

What we DO NOT know: ●

when they were formed,

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where they now reside,

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what happened to them over time,

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where to look for them.

What we DO know:

What we DO know:

Z=0

So what can we do? :-(

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Construct realistic numerical models,

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Focus on relevant processes,

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Use suitable equations.

Equations :-)

Lecture notes – Chapter 6 :-)

Ingredients of the Models ●

Opacity,

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Energy generation,

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Convection and Mixing,

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Boundary conditions,

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Initial Conditions.

What do we desire? ●

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Contiunous variables such as photon flux and broadband colors, Atmospheres allowed to have small convective regions, He burning is the last evolutionary phase – its end terminates the star's life, Shape vary smoothly with mass.

Results

H-R diagram

Why Population III Stars are Hot?

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Metal-poor environment,

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Reduced opacity.

Emission-lines

Example of ”observed” spectra

Conclusions

Population III stars produce lots of ionizing photons – might leads to unusual radiative feedback effects on the interstellar matter.

Conclusions

They are expected to have unusually high equivalent widths of Lyα and He II lines. These lines will probably be the primary means of detecting and identifying the first stars.

Thank you for your attention!