Inhomogeneous Stellar Atmospheres

恒星的特征通常是从内部(通常温度为几百万开尔文)到表面(温度为几千或几万开尔文)温度下降。在太阳和其他表面(即光球层)温度约为6000 K或更低的恒星中，由于磁性表面活动所沉积的能量，透明的最外层的温度急剧上升。在太阳中，温度开始上升的区域传统上被称为色球。最近，引起这种温度反转的过程被称为“分子冷却灾难”，因为CO和其他分子的辐射冷却似乎是造成这种现象的原因。首席研究员(PI)建议研究晚型恒星大气中的温度反转区域，并将它们与太阳的大气反转区域进行比较。观测输入数据将是这些恒星的空间未分辨光谱，这是Pi和他的合作者在过去三年中积累的。这些数据将由能够解决分子非局部热力学平衡(NLTE)问题的计算机代码处理。

Stars are generally characterized by a decrease in their temperature from the interior (where the temperature is typically millions of degrees Kelvin) to the surface (where the temperature is thousands or tens of thousands of degrees Kelvin). In the sun and other stars with surface (i.e., photospheric) temperatures of roughly 6000 K and less the temperature rises sharply in the transparent, outermost layers due to energy deposited from magnetic surface activities. In the sun, the region in which the temperature starts rising has traditionally been known as the chromosphere. More recently, the processes giving rise to this temperature inversion have been called the "molecular cooling catastrophes" because radiative cooling by CO and other molecules appears to be responsible for it. The Principal Investigator (PI) proposes to study the regions of temperature inversion in the atmospheres of late-type stars and compare them to those of the sun. The observational input data will be spatially-unresolved spectra of these stars, which the PI and his collaborators have accumulated over the past three years. This data will be processed by computer codes capable of solving the molecular non-local thermodynamic equilibrium (NLTE) problem.