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arXiv 1802.00183astro-ph.SR
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共生星AG Peg的H $α$和H $β$喇曼散射线轮廓

The H$α$ and H$β$ Raman-scattering line profiles of the symbiotic star AG Peg

Seong-Jae Lee, Siek Hyung

摘要:

1998年9月观测到的共生星AG Peg的H $α$和H $β$谱线剖面(相位$ϕ$ = 10.24)显示出顶部窄的双高斯和底部宽的(半高宽为200 - 400 km $^{-1}$)分量。光电离模型表明,产生氢的巴耳末线和莱曼线的电离区是辐射束缚的,氢气数密度为$n_{\rm H} \sim 10^{9.85}$ cm $^{-3}$,气体温度为T $_e$ = 12 000 - 15 000 K.我们进行了Monte Carlo模拟,以适应拉曼散射宽翼,假设氢Ly $β$和Ly $γ$线发射的辐射范围内的HII区周围的白矮星具有相同的双高斯线轮廓形状的氢巴耳末线。模拟表明,散射HI区连接到(或位于外面)的内部HII壳。与所观察到的宽HI线轮廓的最佳拟合表明,散射中性区的柱密度为$N_{\rm H} \simeq $ 3 - 5 $\times$ 10 $^{19}$ cm $^{-2}$。我们研究了所观察到的H $α$和H $β$线轮廓的几何结构是否是一个双极锥壳结构,由辐射约束的电离区和外部材料约束的中性区。膨胀的双极结构可能是热白矮星周围共同包层或罗氏瓣外壳的两个相对区域,通过来自巨星的质量流入形成,并被来自热白矮星的快风推出。

英文摘要:

The H$α$ and H$β$ line profiles of the symbiotic star AG Peg observed on 1998 September (phase $ϕ$ = 10.24), display the top narrow double Gaussian and bottom broad (FWHM of 200 -- 400 kms$^{-1}$) components. The photo-ionization model indicated that the ionized zone, responsible for the hydrogen Balmer and Lyman lines, is radiation-bounded, with a hydrogen gas number density of $n_{\rm H} \sim 10^{9.85}$ cm$^{-3}$ and a gas temperature of T$_e$ = 12\,000 -- 15\,000~K. We carried out Monte Carlo simulations to fit the Raman scattering broad wings, assuming that the hydrogen Ly$β$ and Ly$γ$ lines emitted within the radiation-bounded HII zone around a white dwarf have the same double Gaussian line profile shape as the hydrogen Balmer lines. The simulation shows that the scattering HI zones are attached to (or located just outside of) the inner HII shells. The best fit to the observed broad HI line profiles indicates that the column density of the scattering neutral zone is $N_{\rm H} \simeq $ 3 -- 5 $\times$ 10$^{19}$ cm$^{-2}$. We examined whether the geometrical structure responsible for the observed H$α$ and H$β$ line profiles is a bipolar conical shell structure, consisting of the radiation-bounded ionized zone and the outer material bounded neutral zone. The expanding bipolar structure might be two opposite regions of the common envelope or the outer shell of the Roche lobe around the hot white dwarf, formed through the mass inflows from the giant star and pushed out by the fast winds from the hot white dwarf.

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