| Abstract from DBPedia | The asymptotic giant branch (AGB) is a region of the Hertzsprung–Russell diagram populated by evolved cool luminous stars. This is a period of stellar evolution undertaken by all low- to intermediate-mass stars (about 0.5 to 8 solar masses) late in their lives. Observationally, an asymptotic-giant-branch star will appear as a bright red giant with a luminosity ranging up to thousands of times greater than the Sun. Its interior structure is characterized by a central and largely inert core of carbon and oxygen, a shell where helium is undergoing fusion to form carbon (known as helium burning), another shell where hydrogen is undergoing fusion forming helium (known as hydrogen burning), and a very large envelope of material of composition similar to main-sequence stars (except in the case of carbon stars).漸近巨星分枝（ぜんきんきょせいぶんし、asymptotic giant branch）または漸近巨星枝（ぜんきんきょせいし）は、ヘルツシュプルング・ラッセル図（HR図）において、低温で明るい、進化の進んだ恒星が分布する部分。小中質量星（0.8から8太陽質量 (M☉) ）は全てその生涯の後半にこの段階を経る。 観測上は、太陽より数千倍明るい赤色巨星のように見える。酸素と炭素からなるほとんど不活性な中心核と、ヘリウムの核融合で炭素が形成される殻、水素の核融合でヘリウムが形成される殻、通常の恒星と似た化学組成を持つ非常に大きな外層、といった内部構造を持つ。 (Source: http://dbpedia.org/resource/Asymptotic_giant_branch) |
