arXiv 0812.42182008-12-22astro-ph

光谱双星Herbig Ae星RS Cha中非径向脉动的发现

Discovery of non-radial pulsations in the spectroscopic binary Herbig Ae star RS Cha

T. Böhm, W. Zima, C. Catala, E. Alecian, K. Pollard, D. Wright

备注：: 12 pages, 15 figures, submitted to A&A
DOI：: 10.1051/0004-6361/200811460

摘要：

在这篇文章中，我们提出了第一次发现的非径向脉动的两个组成部分的Herbig Ae光谱双星RS车。在14个观测夜晚（2006年1月），在1米的Mt John（新西兰）望远镜上用Hercules高分辨率阶梯光栅摄谱仪对该双星进行了准连续观测。在恒星上的累积曝光时间为44小时，对应于255个单独的高分辨率阶梯光栅光谱与$R = 45000$。最小二乘反卷积光谱（LSD）获得的每一个光谱表示的有效光球吸收曲线修改脉动。通过减去旋转加宽的人工轮廓计算差谱;分析这些残余谱并检测非径向脉动。随后的分析与两个互补的方法，即傅立叶参数拟合（FPF）和傅立叶2D（F2 D）已执行和第一约束的脉动模式已被导出。事实上，光谱双星的两个组成部分都是Herbig Ae星，并且都显示出NRP。用FPF方法识别出2个主分量模，（1，m）=（11，11），（11，9）或（10，6）时f_1 = 21.11 c/d，（1，m）=（10，6）或（9，5）时f_2 = 30.38 c/d，其中（1，m）=（11，11），（11，9）或（10，6）。F2 D分析表明，对于f_1，度数l = 8-10。对于二次分量，FPF方法识别出3个（l，m）模，它们按概率降序排列：（l，m）=（2，1）或（2，2）时f_1 = 12.81 c/d，（l，m）=（13，5）或（10，5）时f_2b = 19.11 c/d，（l，m）=（6，3）或（6，5）时f_3 = 24.56 c/d。F2 D分析表明f_1的度数l = 2或3，但提出了将f_2识别为径向脉动的矛盾识别（l = 0）。

英文摘要：

In this article we present a first discovery of non radial pulsations in both components of the Herbig Ae spectroscopic binary star RS Cha. The binary was monitored in quasi-continuous observations during 14 observing nights (Jan 2006) at the 1m Mt John (New Zealand) telescope with the Hercules high-resolution echelle spectrograph. The cumulated exposure time on the star was 44 hrs, corresponding to 255 individual high-resolution echelle spectra with $R = 45000$. Least square deconvolved spectra (LSD) were obtained for each spectrum representing the effective photospheric absorption profile modified by pulsations. Difference spectra were calculated by subtracting rotationally broadened artificial profiles; these residual spectra were analysed and non-radial pulsations were detected. A subsequent analysis with two complementary methods, namely Fourier Parameter Fit (FPF) and Fourier 2D (F2D) has been performed and first constraints on the pulsation modes have been derived. In fact, both components of the spectroscopic binary are Herbig Ae stars and both show NRPs. The FPF method identified 2 modes for the primary component with (degree l, azimuthal number m) couples ordered by decreasing probability: f_1 = 21.11 c/d with (l,m) = (11,11), (11,9) or (10,6) and f_2 = 30.38 c/d with (l,m) = (10,6) or (9,5). The F2D analysis indicates for f_1 a degree l = 8-10. For the secondary component, the FPF method identified 3 modes with (l,m) ordered by decreasing probability: f_1 = 12.81 c/d with (l,m) = (2,1) or (2,2), f_2b = 19.11 c/d with (l,m) = (13,5) or (10,5) and f_3 = 24.56 c/d with (l,m) = (6,3) or (6,5). The F2D analysis indicates for f_1 a degree l = 2 or 3, but proposes a contradictory identification of f_2 as a radial pulsation (l = 0).

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