A comprehensive analysis of the cool RCB star DY Persei
A comprehensive analysis of the cool RCB star DY Persei
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全面解析酷炫RCB明星DY Persei
DOI：
10.1051/0004-6361:20066923
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
O. Alksnis
中科院分区：
文献类型：
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作者：
L. Začs;S. Mondal;Wen;A. F. Pugach;F. Musaev;F. Musaev;O. Alksnis
上下文。从理论上讲，冷的北冕R星(RCB)的数量应该比暖的RCB多，然而，到目前为止，只发现了几个候选恒星。目标。给出了极冷的RCB候选星DY Per和附近的匿名恒星(台北星)的观测结果，以确定它的基本参数和演化状态。方法：研究方法。2004年进行了深光衰变条件下的CCDBVRI测光和低分辨率光谱分析。采集了2002年最大光强附近的高分辨率光谱，并与典型的各类碳星进行了定性分析。结果。据Zay cs等人报道，在最高光点附近，有一颗距离为∼2.��5的匿名恒星。(2005a，A&A，438，L13)被DY Per相形见绌。然而，在B和V波段，分量在深光衰变时被分解，附近的恒星在B波段比DY本身更亮一些。BV(R)首次用PSF光度法估计了各组分的个体大小。2004年的轻微下降是DY Per有史以来观察到的最深的下降，B=18.16 MAG。DY Per在光衰变时的单个颜色指数，(B−V)=2.35和(V−R)�1.9，对于碳星来说并不是典型的。在光谱中，C2和CN分子的吸收特征占优势，但在深光衰减时，显著的C2吸收带被显著遮蔽，并且可以看到NaI D12的广泛的(FWHM∼600 KM S−1)发射特征。怀疑是在C2(1，0)带头和4227A的CaI谱线上的发射。DY Per相对于碳星样品的分析，证实了显著的缺氢，高的碳丰度，相对较高的12C/13C比值和太阳金属丰度。因此，DY Per可能是一个很酷的极端银河系RCB的原型。附近的恒星在B和V波段变化不大，B=17.8mag。当观测到的颜色指数(B−V)=1.00和(V−R)�0.6时，它可能是一颗与DY Per没有物理联系的G0矮星，尽管到两颗恒星的距离相似，d∼1.5kpc。
Context. Theoretically, the number of cool Galactic R Coronae Borealis stars (RCBs) should be greater than the warm RCBs, however to date, only a few candidates have been detected. Aims. Observations of the extremely cool RCB candidate, DY Per, and the anonymous nearby star (the “Taipei star”) are presented to specify its fundamental parameters and evolutionary status. Methods. CCD BVRI photometry and low-resolution spectroscopy at deep light decline was carried out in 2004. A high-resolution spectrum was gathered near the maximum light in 2002, and a qualitative analysis was made relative to the typical carbon stars of various types. Results. Near the light maximums, the nearby anonymous star with a separation of ∼2. �� 5 reported by Zay cs et al. (2005a, A&A, 438, L13) was outshined by DY Per. However, in the B and V band the components are resolved at deep light decline and the nearby star is somewhat brighter in B than DY Per itself. BV(R) individual magnitudes of the components were estimated using PSF photometry for the first time. The light decline in 2004 was the deepest ever observed for DY Per, B = 18.16 mag. The individual colour indices of DY Per at light decline, (B − V) = 2.35 and (V − R) � 1.9, are not typical for carbon stars. In the spectrum, absorption features of C2 and CN molecules prevail, however, prominent C2 absorption bands are significantly veiled at deep-light decline and a broad (FWHM ∼ 600 km s −1 ) emission feature of Na i D12 is visible. Emissions are suspected in the C2 (1,0) bandhead and in Ca i line at 4227 A. Analysis of DY Per relative to the sample of carbon stars, verifies the significant hydrogen deficiency, high carbon abundance, relatively high 12 C/ 13 C ratio and solar metallicity. Thus DY Per could be a prototype of cool extreme Galactic RCBs. The nearby star does not vary appreciably in the B and V bands, B = 17.8 mag. With the observed colour indices (B − V) = 1.00 and (V − R) � 0.6, it may be a G0 dwarf not physically related to DY Per, although the distances to both stars are similar, d ∼ 1.5 kpc.