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Книга Бориса В. Васильева " Астрофизика "

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" Астрофизика "

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Ãëàâà 6<br />

Âíóòðåííåå ñòðîåíèå çâåçäû<br />

Ýíåðãåòè÷åñêàÿ âûãîäíîñòü äëÿ ïëàçìû ïðè î÷åíü âûñîêîé òåìïåðàòóðå èìåòü<br />

ïîñòîÿííóþ ïëîòíîñòü ïîäñêàçûâàåò, ÷òî òàêèì ñâîéñòâîì äîëæíà îáëàäàòü<br />

ïëàçìà â öåíòðàëüíîé îáëàñòè çâåçäû. Ïðîâåäåííûå íèæå âû÷èñëåíèÿ ïîêàæóò,<br />

÷òî ïî ýíåðãåòè÷åñêèì ñîîáðàæåíèÿ âûãîäíî, ÷òîáû ýòà öåíòðàëüíàÿ îáëàñòü<br />

çâåçäû - ÿäðî - îáëàäàëà ñòðîãî îïðåäåëåííîé ìàññîé, ðàâíîé ïîëîâèíå âñåé<br />

ìàññû çâåçäû, è ñòðîãî ôèêñèðîâàííûì ðàäèóñîì ïîðÿäêà 1/10 åå ðàäèóñà, ò.å.<br />

âûñîêîïëîòíîå ÿäðî çàíèìàåò ïðèìåðíî 1/1000 äîëþ åå îáúåìà. Äðóãàÿ<br />

ïîëîâèíà âåùåñòâà çâåçäû ðàñïðåäåëÿåòñÿ âî âíåøíåé ïî îòíîøåíèþ ê ÿäðó<br />

îáëàñòè ñ îòíîñèòåëüíî ìàëîé ïëîòíîñòüþ. Ïîýòîìó ýòó îáëàñòü ìîæíî<br />

íàçûâàòü àòìîñôåðîé çâåçäû.<br />

6.1 Ðàâíîâåñèå ïëàçìû â ÿäðå çâåçäû<br />

Óñëîâèå ðàâíîâåñèÿ (5.3) äëÿ ïëàçìû ñ ýíåðãåòè÷åñêè âûãîäíîé ïîñòîÿííîé<br />

ïëîòíîñòüþ n s = const äîñòèãàåòñÿ ïðè<br />

P = √ Gγ ⋆r, (6.1)<br />

çäåñü ïëîòíîñòü ìàññû γ ⋆ = A Z mpn⋆.<br />

 ýòîì ñëó÷àå ïëàçìà ïðèîáðåòàåò ýëåêòðè÷åñêèé çàðÿä ñ ïëîòíîñòüþ<br />

˜ϱ = √ Gγ ⋆, (6.2)<br />

à ýëåêòðè÷åñêîå ïîëå, äåéñòâóþùåå íà ÿ÷åéêó<br />

Ẽ =<br />

g √<br />

G<br />

. (6.3)<br />

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