Population III Stars

With [Fe/H]$\ifmmode {\,\mathbin{\lower 3pt\hbox {$\,\rlap{\raise 8pt\hbox{$\char'074$}}\ma... ... 3pt\hbox {$\rlap{\raise 8pt\hbox{$\char'074$}}\mathchar''7218\,$}}} $}\fi -5$, cooling is inefficient.

Initial stellar mass may be high.

Low metallicity stars probably lose little mass.

Wind losses are suppressed.

Pulsational instabilities are weak, slow.

Fate of star depends on mass.

$10\,M_\odot\ifmmode {\,\mathbin{\lower 3pt\hbox {$\,\rlap{\raise 8pt\hbox{$\cha... ... {$\rlap{\raise 8pt\hbox{$\char'074$}}\mathchar''7218\,$}}} $}\fi 40\,M_\odot$, normal supernova.

$40\,M_\odot\ifmmode {\,\mathbin{\lower 3pt\hbox {$\,\rlap{\raise 8pt\hbox{$\cha... ... {$\rlap{\raise 8pt\hbox{$\char'074$}}\mathchar''7218\,$}}} $}\fi 100\,M_\odot$, collapse to BH?

$100\,M_\odot\ifmmode {\,\mathbin{\lower 3pt\hbox {$\,\rlap{\raise 8pt\hbox{$\ch... ... {$\rlap{\raise 8pt\hbox{$\char'074$}}\mathchar''7218\,$}}} $}\fi 250\,M_\odot$, no remnant.

$M\ifmmode {\mathbin{\lower 3pt\hbox {$\,\rlap{\raise 8pt\hbox{$\char'076$}}\mat... ... {$\rlap{\raise 8pt\hbox{$\char'076$}}\mathchar''7218\,$}}} $}\fi 250\,M_\odot$, collapse to BH?

If many Pop III stars have $M_0\ifmmode {\mathbin{\lower 3pt\hbox {$\,\rlap{\raise 8pt\hbox{$\char'076$}}\m... ... {$\rlap{\raise 8pt\hbox{$\char'076$}}\mathchar''7218\,$}}} $}\fi 250\,M_\odot$, could lead to IMBH (Madau & Rees 2001).

Still many uncertainties (rotation, HD, dissociation/creation of $H_2$, etc.).