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Earth and Space Sciences · 术语表

什么是 G-dwarf problem？

Definition 30.11 University Earth and Space Sciences — Year 3 · 第 30 章 — Where the Elements Come From

The G-dwarf problem is the shortage of metal-poor long-lived stars in the solar neighbourhood compared with the prediction of the closed-box model: far fewer of the long-lived dwarf stars of spectral type G have low metallicities than a closed box would have made.

$A two-phase model of [ / Fe] in a closed box: the plateau at +0.4 is the ratio made by core-collapse supernovae; Type Ia supernovae, which begin when the gas has reached [ Fe/H] = -1, then add iron at a steady rate, until the ratio is solar at [ Fe/H] = 0. The plateau and the knee are those seen in the stars of the Galaxy; the shape between is the model’s. At the Sun’s metallicity, 60\,\% of the iron in this model has come from Type Ia supernovae.$

A two-phase model of

[\alpha/\mathrm{Fe}]

in a closed box: the plateau at

+0.4

is the ratio made by core-collapse supernovae; Type Ia supernovae, which begin when the gas has reached

[\mathrm{Fe/H}] = -1

, then add iron at a steady rate, until the ratio is solar at

[\mathrm{Fe/H}] = 0

. The plateau and the knee are those seen in the stars of the Galaxy; the shape between is the model’s. At the Sun’s metallicity,

60\,\%

of the iron in this model has come from Type Ia supernovae.

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