DIRECT DIAGNOSTICS OF FORMING MASSIVE STARS: STELLAR PULSATION AND PERIODIC VARIABILITY OF MASER SOURCES
DIRECT DIAGNOSTICS OF FORMING MASSIVE STARS: STELLAR PULSATION AND PERIODIC VARIABILITY OF MASER SOURCES
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DOI：
10.1088/2041-8205/769/2/l20
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发表时间：
2013-04
期刊：
影响因子：
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通讯作者：
K. Inayoshi;K. Sugiyama;T. Hosokawa;K. Motogi;Kei E. I. Tanaka
中科院分区：
文献类型：
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作者：
K. Inayoshi;K. Sugiyama;T. Hosokawa;K. Motogi;Kei E. I. Tanaka
6.7 GHz甲醇脉泽辐射是大质量恒星形成的一种示踪物，有时会在几个10-100天内显示出神秘的周期性通量变化。在这封信中，我们提出，这些周期性的变化可以解释为脉动的大质量原恒星下快速质量吸积率增长。我们的恒星演化计算预测，大质量的原恒星有非常大的半径超过100 R的最大值，在这里，我们研究的脉动稳定性的膨胀的原恒星的线性稳定性分析的方式。我们表明，原恒星变得脉动不稳定，根据吸积率的不同，周期为10-100天。考虑到星星脉动不稳定时的恒星光度也依赖于吸积率，我们导出了周期-光度关系log（L/ L）= 4.62 + 0.98log（P/100天），这个关系可以用未来的观测来检验。我们的模型进一步表明，脉动大质量原恒星的半径和质量也应该取决于周期。这将有可能推断出这种原恒星的性质和吸积率与观察周期。测量脉泽周期可以直接诊断吸积大质量原恒星的结构，这些原恒星深深嵌入致密气体中，无法通过其他观测方法获得。
The 6.7 GHz methanol maser emission, a tracer of forming massive stars, sometimes shows enigmatic periodic flux variations over several 10–100 days. In this Letter, we propose that these periodic variations could be explained by the pulsation of massive protostars growing under rapid mass accretion with rates of . Our stellar evolution calculations predict that the massive protostars have very large radii exceeding 100 R☉ at maximum, and here we study the pulsational stability of such bloated protostars by way of the linear stability analysis. We show that the protostar becomes pulsationally unstable with various periods of several 10–100 days depending on different accretion rates. With the fact that the stellar luminosity when the star is pulsationally unstable also depends on the accretion rate, we derive the period–luminosity relation log (L/ L☉) = 4.62 + 0.98log (P/100 days), which is testable with future observations. Our models further show that the radius and mass of the pulsating massive protostar should also depend on the period. It would be possible to infer such protostellar properties and the accretion rate with the observed period. Measuring the maser periods enables a direct diagnosis of the structure of accreting massive protostars, which are deeply embedded in dense gas and are inaccessible with other observations.