In this paper, the influence of chemi-ionization processes in $H^*(n \ge 2) + H(1s)$ collisions, as well as the influence of inverse chemi-recombination processes on hydrogen atom excited-state populations in solar photosphere, are compared with the influence of concurrent electron-atom and electron-ion ionization and recombination processes. It has been found that the considered chemi-ionization/recombination processes dominate over the relevant concurrent processes in almost the whole solar photosphere. Thus, it is shown that these processes and their importance for the non-LTE modeling of the solar atmosphere should be investigated further.
Period-colour and amplitude-colour (PCAC) relations can be used to probe both the hydrodynamics of outer envelope structure and evolutionary status of Cepheids and RR Lyraes. In this work, we incorporate the PCAC relations for RR Lyraes, BL Her, W Vir and classical Cepheids in a single unifying theory that involves the interaction of the hydrogen ionization front (HIF) and stellar photosphere and the theory of stellar evolution. PC relations for RR Lyraes and classical Cepheids using OGLE-IV data are found to be consistent with this theory: RR Lyraes have shallow/sloped relations at minimum/ma…
Period-color (PC) relations may be used to study the interaction of the stellar photosphere and the hydrogen ionization front (HIF). RR Lyraes (RRLs) and long period classical Cepheids (P > 10d) have been found to exhibit different PC behavior at minimum and maximum light which can be explained by the HIF-photosphere interaction based on their location on the HR diagram. In this work, we extend the study to include type II Cepheids (T2Cs) with an aim to test the HIF-photosphere interaction theory across a broad spectrum of variable star types. We find W Vir stars and BL Her stars to have simil…
We investigate the effects of interactions between ions and neutrals on the chromosphere and overlying corona using 2.5D radiative MHD simulations with the Bifrost code. We have extended the code capabilities implementing ion-neutral interaction effects using the Generalized Ohm's Law, i.e., we include the Hall term and the ambipolar diffusion (Pedersen dissipation) in the induction equation. Our models span from the upper convection zone to the corona, with the photosphere, chromosphere and transition region partially ionized. Our simulations reveal that the interactions between ionized parti…
The temperature and density conditions in the magnetized photosphere and chromosphere of the Sun lead to a very small degree of atomic ionization. In addition, at particular height, the magnetic field may be strong enough to give rise to a cyclotron frequency larger than the collisional frequency for some species, while for others the opposite may happen. These circumstances influence the collective behavior of the particles and some of the hypotheses of magnetohydrodynamics may be relaxed, giving rise to non-ideal MHD effects. In this paper we discuss our recent developments in modeling non-i…
Over the last decades, realistic 3D radiative-MHD simulations have become the dominant theoretical tool for understanding the complex interactions between the plasma and the magnetic field on the Sun. Most of such simulations are based on approximations of magnetohydrodynamics, without directly considering the consequences of the very low degree of ionization of the solar plasma in the photosphere and bottom chromosphere. The presence of large amount of neutrals leads to a partial decoupling of the plasma and the magnetic field. As a consequence of that, a series of non-ideal effects (ambipola…
Investigation of the magnetic and temperature sensitivity of the Stokes parameters of absorption lines in the solar photosphere
在温度，压力，微湍流速度和磁场强度的扰动的响应函数进行了计算的斯托克斯参数配置文件的线Fe I 525.06，525.02和Fe II 614.92 nm。采用Grossmann-Doerth、Larsson和Solanki（1988）提出的程序。我们表明，抑郁症的响应函数不仅可以用来确定的深度，在物理条件的变化影响最有效的吸收和发射的连续和线，但估计响应的斯托克斯配置文件以及。响应是使用敏感度指标估计的，敏感度指标是作为所有光球层响应函数的积分计算的。在高激发和电离势的谱线上，如O I、C I、Fe II谱线，发现了斯托克斯谱线的反常温度敏感性。随着温度的升高，这些谱线的凹陷度增大而不是减小。斯托克斯剖面的磁灵敏度主要取决于磁场条件。在弱场和中场条件下，对于朗德因子、波长和等效宽度值较大的光球线，V剖面的响应最大。灵敏度指标的计算结果，连同磁和温度增强的指数的磁力线。
Supergranulation is characterized by horizontally divergent flows with typical length scales of 32 Mm in the solar photosphere. Unlike granulation, the size of which is comparable to both the thickness of the radiative boundary layer and local scale height of the plasma in the photosphere, supergranulation does not reflect any obvious length scale of the solar convection zone. Early suggestions that the depth of second helium ionization is important are not supported by numerical simulations. Thus the origin of the solar supergranulation remains largely a mystery. Moreover, observations of flo…
Anomalously Strong Localized First Ionization Potential Effect Associated with a Solar Subflare
State Key Laboratory of Lunar and Planetary Sciences and CNSA Macau Center for Space Exploration and Science, Macau University of Science and Technology（澳门科技大学月球与行星科学国家重点实验室及CNSA澳门空间探索科学中心）；School of Astronomy and Space Science and Key Laboratory of Modern Astronomy and Astrophysics, Nanjing University（南京大学天文与空间科学学院现代天体物理学重点实验室）
One puzzling question in solar physics is the difference between elemental abundances in the photosphere and the corona. Elements with low first ionization potential (FIP) can be overabundant in the corona compared to the photosphere under certain circumstances. The same phenomenon has been observed on a handful of stars, while a few of them show the inverse effect. But not all the stars in the original sample had precise photospheric abundances derived from optical spectra, so for some the solar values were adopted. In this work we make homogeneous abundance measurements from optical spectros…
From a turbulent history, the study of abundances of elements in solar energetic particles (SEPs) has grown into an extensive field that probes the solar corona and the physical processes of SEP acceleration and transport. Underlying SEPs are the abundances of the solar corona, which differ from photospheric abundances as a function of the first ionization potentials (FIPs) of the elements. The FIP-dependence of SEPs also differs from that of the solar wind; each has a different magnetic environment where low-FIP ions and high-FIP neutral atoms rise toward the corona. Two major sources generat…
In our previous research, it has been demonstrated that such inelastic processes in atom Rydberg-atom collisions, as chemi-ionization and (n-n') mixing, should be considered together. Here we will review the present state of the art and the actual problems will be discussed. In this context, we will consider the influence of the (n-n')-mixing during a symmetric atom Rydberg-atom collision processes on the intensity of chemi-ionization process. It will be taken into account H(1s) + H*(n) collisional systems, where the principal quantum number n $>>$ 1. It will be demonstrated that the inclusion…
In order to study chromospheric magnetosonic wave propagation including, for the first time, the effects of ion-neutral interactions in the partially ionized solar chromosphere, we have developed a new multi-fluid computational model, accounting for ionization and recombination reactions in gravitationally stratified magnetized collisional media. The two-fluid model used in our 2D numerical simulations treats neutrals as a separate fluid and considers charged species (electrons and ions) within the resistive MHD approach with Coulomb collisions and anisotropic heat flux determined by Braginski…
To study acoustic wave propagation and the corresponding energy deposition in partially ionized plasmas, we use a two-fluid computational model that treats neutrals and charged particles (electrons and ions) as two separate fluids. This two-fluid model takes into account the ion-neutral collisions, ionization, and recombination, allowing us to investigate both the collisional and reactive interactions between uncoupled ions and neutrals in the plasmas. In the present numerical simulations, the initial density is specified to reach hydrostatic equilibrium, and as a comparison, chemical equilibr…
Anomalies in the abundance measurements of short lived radionuclides in meteorites indicate that the protosolar nebulae was irradiated by a large number of energetic particles ($E\gtrsim10\,$MeV), often called solar cosmic rays. The particle flux of the contemporary Sun cannot explain these anomalies, but, similar to \mbox{T Tauri} stars, the young Sun was more active and probably produced enough high energy particles. However, the stellar particle (SP) flux of young stars is essentially unknown. We model the impact of high-energy ionization sources on the chemistry of the circumstellar enviro…
