天文学进展
天文學進展
천문학진전
PROGRESS IN ASTRONOMY
2010年
1期
39-52
,共14页
太阳过渡区%色球%紫外辐射
太暘過渡區%色毬%紫外輻射
태양과도구%색구%자외복사
Solar Transition Region%Chromosphere%UV radiation
氢是太阳大气中最主要的元素.氢原子的赖曼(Lyman)谱线,尤其是赖曼阿尔法(Ly-α)谱线的辐射,是太阳色球和低过渡区能量损失的主要形式.在太阳的赖曼α像中,网络组织的辐射比较强,而辐射最强的地方是活动区.由于存在辐射转移效应,在宁静区,低阶赖曼谱线的谱形中央一般会形成一个凹陷,而在中央两侧则形成两个峰,两峰往往呈现出一定的不对称性.数值模拟和观测研究表明,赖曼谱线双峰的不对称性与高层大气中各种系统性流动有关.在太阳活动区,赖曼谱形在谱斑区与在宁静区类似;而在黑子区,赖曼谱形几乎没有中央凹陷.赖曼谱形也可用于诊断日珥、耀斑和日冕物质抛射等结构和现象的等离子体特性.该文回顾了赖曼谱线的观测历史,阐明了观测与模拟结果所揭示的物理过程,并结合笔者的认识进行了相应的评论.
氫是太暘大氣中最主要的元素.氫原子的賴曼(Lyman)譜線,尤其是賴曼阿爾法(Ly-α)譜線的輻射,是太暘色毬和低過渡區能量損失的主要形式.在太暘的賴曼α像中,網絡組織的輻射比較彊,而輻射最彊的地方是活動區.由于存在輻射轉移效應,在寧靜區,低階賴曼譜線的譜形中央一般會形成一箇凹陷,而在中央兩側則形成兩箇峰,兩峰往往呈現齣一定的不對稱性.數值模擬和觀測研究錶明,賴曼譜線雙峰的不對稱性與高層大氣中各種繫統性流動有關.在太暘活動區,賴曼譜形在譜斑區與在寧靜區類似;而在黑子區,賴曼譜形幾乎沒有中央凹陷.賴曼譜形也可用于診斷日珥、耀斑和日冕物質拋射等結構和現象的等離子體特性.該文迴顧瞭賴曼譜線的觀測歷史,闡明瞭觀測與模擬結果所揭示的物理過程,併結閤筆者的認識進行瞭相應的評論.
경시태양대기중최주요적원소.경원자적뢰만(Lyman)보선,우기시뢰만아이법(Ly-α)보선적복사,시태양색구화저과도구능량손실적주요형식.재태양적뢰만α상중,망락조직적복사비교강,이복사최강적지방시활동구.유우존재복사전이효응,재저정구,저계뢰만보선적보형중앙일반회형성일개요함,이재중앙량측칙형성량개봉,량봉왕왕정현출일정적불대칭성.수치모의화관측연구표명,뢰만보선쌍봉적불대칭성여고층대기중각충계통성류동유관.재태양활동구,뢰만보형재보반구여재저정구유사;이재흑자구,뢰만보형궤호몰유중앙요함.뢰만보형야가용우진단일이、요반화일면물질포사등결구화현상적등리자체특성.해문회고료뢰만보선적관측역사,천명료관측여모의결과소게시적물리과정,병결합필자적인식진행료상응적평론.
Hydrogen is the most abundant element in the solar atmosphere and its resonance lines, especially the Lyman-alpha (Ly-α) line, plays an important role in the overall radiative energy transport of the Sun. In this paper we review the observational and modeling results on the solar hydrogen Lyman line emissionsThe Ly-α line was used to observe the Sun since 1950s, when the era of space just began. It was found that the Ly-α emission is enhanced at lanes of the chromospheric network, and the brightest features in Ly-α images are active regions. However, so far no continuous Ly-α observation with both high spatial and temporal resolutions has been done.In the normal quiet Sun region, due to the effect of radiative transfer, the average lower-order Lyman line (Ly-β through Ly-ε) profiles are found to be self-reversed at the centers and stronger in the red-horns. While the higher H Lyman series line (beyond Ly-ζ) profiles are flat-topped or even Gaussian-shaped. Recently, the Ly-α profiles were also obtained with the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) instrument in high spectral, temporal, and spatial resolutions. It turns out that most Ly-α profiles are strongly reversed and stronger in the blue horns. It is believed that the opposite asymmetries in the average profiles of Ly-α and higher Lyman lines are probably caused by the combined effect of flows in the different layers of the solar atmosphere and opacity differences of the lines. A mechanism for line formation can not be simply imagined but must be thoroughly devised and further investigated with the help of models.In active regions, Lyman line profiles, especially Ly-α and Ly-β profiles, were obtained from early rocket observations and found to be similar to those in the quiet Sun. However, profiles obtained in these early observations suffered from geocoronal absorption. SUMER observations avoided this problem and revealed that the Lyman line profiles in sunspots show properties different from the average profiles. The self-reversals of the hydrogen Lyman line profiles are almost absent in umbra regions. In the sunspot plume, the Lyman lines are also not reversed. While the lower-order Lyman line profiles observed in the plage region are obviously reversed, a phenomenon also found in the normal quiet Sun. This result indicates that the opacity of the hydrogen lines is much smaller above sunspots, as compared to plage regions. The ability of diagnosing plasma properties in solar flares and CMEs by analyzing the Lyman line profiles is also demonstrated.Hydrogen Lyman lines were also frequently used to reveal information on the fine structures and physical properties of quiescent solar prominences. Observations and modelings show that the profiles are more reversed when seen across than along the magnetic field lines.