FERRUM项目：[ FeII ]中禁戒线的跃迁概率和实验亚稳态寿命
The FERRUM project: Transition probabilities for forbidden lines in [FeII] and experimental metastable lifetimes
摘要：
准确的禁戒线跃迁几率是低密度天体物理等离子体的重要诊断参数。在本文中，我们提出了实验原子数据禁[Fe II]过渡，观察到的天体物理光谱的强大功能。目的：测量Fe Ⅱ中3d^6（^3G）4s a ^4 G_{11/2}和3d^6（^3D）4s b ^4 D_{1/2}亚稳态能级的寿命，以及禁戒跃迁3d^7 a ^4 F_{7/2,9/2} - 3d^6（^3G）4s a ^4 G_{11/2}的实验跃迁概率。方法：在离子储存环设施BURCHRING使用激光探测技术测量寿命。天体物理分支分数是从船底座η的光谱中获得的，这些光谱是由哈勃太空望远镜上的太空望远镜成像光谱仪获得的。结合寿命和分支分数，得到绝对跃迁概率。结果如下：已经测量了a^4 G_{11/2}和b^4 D_{1/2}能级的寿命，其值分别为0.75（10）s和0.54（3）s。此外，我们还确定了a^4 F_{7/2,9/2} -a^4 G_{11/2}在4243.97和4346.85 A处的两个禁戒跃迁的跃迁几率。的寿命和跃迁概率进行比较，在文献中的计算值。
英文摘要：
Accurate transition probabilities for forbidden lines are important diagnostic parameters for low-density astrophysical plasmas. In this paper we present experimental atomic data for forbidden [FeII] transitions that are observed as strong features in astrophysical spectra. Aims: To measure lifetimes for the 3d^6(^3G)4s a ^4G_{11/2} and 3d^6(^3D)4s b ^4D_{1/2} metastable levels in FeII and experimental transition probabilities for the forbidden transitions 3d^7 a ^4F_{7/2,9/2}- 3d^6(^3G)4s a ^4G_{11/2}. Methods: The lifetimes were measured at the ion storage ring facility CRYRING using a laser probing technique. Astrophysical branching fractions were obtained from spectra of Eta Carinae, obtained with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. The lifetimes and branching fractions were combined to yield absolute transition probabilities. Results: The lifetimes of the a ^4G_{11/2} and the b ^4D_{1/2} levels have been measured and have the following values, 0.75(10) s and 0.54(3) s respectively. Furthermore, we have determined the transition probabilities for two forbidden transitions of a ^4F_{7/2,9/2}- a ^4G_{11/2} at 4243.97 and 4346.85 A. Both the lifetimes and the transition probabilities are compared to calculated values in the literature.
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