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arXiv 1107.3175astro-ph.SRastro-ph.IM
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NLTE近似下射电、毫米波、亚毫米波和红外波段的合成谱

Synthetic Spectra of Radio, Millimeter, Sub-millimeter and Infrared Regimes with NLTE approximation

Victor De la Luz, Alejandro Lara, Jean-Pierre Raulin

摘要:

我们使用一个名为PAKALMPI的数值代码来计算在安静的条件下,在毫米,亚毫米和红外波长的太阳辐射的合成光谱。PAKALMPI解决了辐射转移方程,非局部热力学平衡(NLTE),在三维几何使用多处理器环境。该代码能够使用三种不透明度函数:经典韧致辐射,H-和逆韧致辐射。在这项工作中,我们计算和比较了两个合成光谱,一个在常见的方式:使用韧致辐射不透明度函数,并考虑一个完全电离的大气;和一个新的考虑韧致辐射,逆韧致辐射和H-不透明度函数在NLTE。我们详细分析了17、212和405 GHz(野边山射电日像仪和太阳亚毫米望远镜使用的频率)低大气发射的局部行为。我们发现,在低海拔(低于500公里),H-是主要的发射机制,并在较高的海拔高度的经典韧致辐射成为主要的发射机制。然而,亮温保持不变。最后,我们发现,逆韧致辐射过程是不重要的无线电发射在这些高度。

英文摘要:

We use a numerical code called PAKALMPI to compute synthetic spectra of the solar emission in quiet conditions at millimeter, sub-millimeter and infrared wavelengths. PAKALMPI solves the radiative transfer equation, with Non Local Thermodynamic Equilibrium (NLTE), in a three dimensional geometry using a multiprocessor environment. The code is able to use three opacity functions: classical bremsstrahlung, H-and inverse bremsstrahlung. In this work we have computed and compared two synthetic spectra, one in the common way: using bremsstrahlung opacity function and considering a fully ionized atmosphere; and a new one considering bremsstrahlung, inverse bremsstrahlung and H- opacity functions in NLTE. We analyzed in detail the local behavior of the low atmospheric emission at 17, 212, and 405 GHz (frequencies used by the Nobeyama Radio Heliograph and the Solar Submillimeter Telescope). We found that the H- is the major emission mechanism at low altitudes (below 500 km) and that at higher altitudes the classical bremsstrahlung becomes the major mechanism of emission. However the brightness temperature remains unalterable. Finally, we found that the inverse bremsstrahlung process is not important for the radio emission at these heights.

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