X-ray emission from dense plasma in classical T Tauri stars: hydrodynamic modeling of the accretion shock
X-ray emission from dense plasma in classical T Tauri stars: hydrodynamic modeling of the accretion shock
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DOI：
10.1051/0004-6361:200810753
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发表时间：
2008-10
影响因子：
6.5
通讯作者：
G. Sacco;C. Argiroffi;C. Argiroffi;S. Orlando;A. Maggio;G. Peres;G. Peres;F. Reale;F. Reale
中科院分区：
文献类型：
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作者：
G. Sacco;C. Argiroffi;C. Argiroffi;S. Orlando;A. Maggio;G. Peres;G. Peres;F. Reale;F. Reale
上下文经典金牛座T星（CTTS）的高光谱分辨率X射线观测表明，存在温度T = 2−3 × 10 6 K、密度ne = 10 11 −10 13 cm −3的等离子体，这在非吸积星中是观测不到的。稳态模型表明，这种发射是由于激波加热的吸积物质，但不允许我们分析物质的稳定性及其在恒星大气中的位置。目标。我们调查的动力学和稳定性的冲击加热吸积材料在经典金牛座T星和恒星色球层的作用，在确定的位置和厚度的冲击区。方法.我们进行一维流体动力学模拟的吸积流的CTTS的色球层的影响，包括重力的影响，从光学薄等离子体的辐射损失，热传导和一个良好的测试详细的模型恒星色球层。我们提出的CTTS MP Mus的参数的基础上的模拟结果。结果。我们发现吸积激波在色球层上方产生了一个最大厚度为1.8 × 109 cm，密度ne = 1011 - 1012 cm-3，温度T = 3 × 106 K，均匀压力等于吸积流的冲压压力（450 dyn cm-2）的热物质板。冲击区的底部穿透色球层，并保持在冲压压力等于热压力的位置。系统随板中材料的准周期不稳定性而演化
Context. High spectral resolution X-ray observations of classical T Tauri stars (CTTSs) demonstrate the presence of plasma at temperature T ∼ 2−3 × 10 6 K and density ne ∼ 10 11 −10 13 cm −3 , which are unobserved in non-accreting stars. Stationary models suggest that this emission is due to shock-heated accreting material, but do not allow us to analyze the stability of the material and its position in the stellar atmosphere. Aims. We investigate the dynamics and stability of shock-heated accreting material in classical T Tauri stars and the role of the stellar chromosphere in determining the position and thickness of the shocked region. Methods. We perform one-dimensional hydrodynamic simulations of the impact of an accretion flow on the chromosphere of a CTTS, including the effects of gravity, radiative losses from optically thin plasma, thermal conduction and a well tested detailed model of the stellar chromosphere. We present the results of a simulation based on the parameters of the CTTS MP Mus. Results. We find that the accretion shock generates an hot slab of material above the chromosphere with a maximum thickness of 1.8 × 10 9 cm, density ne ∼ 10 11 −10 12 cm −3 , temperature T ∼ 3 × 10 6 K, and uniform pressure equal to the ram pressure of the accretion flow (∼450 dyn cm −2 ). The base of the shocked region penetrates the chromosphere and remains at a position at which the ram pressure is equal to the thermal pressure. The system evolves with quasi-periodic instabilities of the material in the slab