arXiv 1501.033732015-01-15astro-ph.SR

行星状星云共包层后Wolf-Rayet中心星的径向速度巡天：NGC 5189密近双星核的首次发现和结果

A radial velocity survey for post-common-envelope Wolf-Rayet central stars of planetary nebulae: First results and discovery of the close binary nucleus of NGC 5189

Rajeev Manick, Brent Miszalski, Vanessa McBride

备注：: Accepted for publication by MNRAS, 22 pages, 7 figures, 10 tables
DOI：: 10.1093/mnras/stv074

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摘要：

行星状星云（[WR] CSPNe）的沃尔夫-拉叶中心星的形成，其光谱外观模仿大质量WR星，仍然知之甚少。最不了解的是[WR] CSPNe的二元伴侣的性质和频率，这可能解释了它们的H缺乏。我们对6个[WR] CSPNe进行了系统的径向速度（RV）研究，以寻找后共同包络（post-CE）[WR]双星。我们使用了互相关的方法来构建RV的时间序列，成功地完成了大质量的近距离双星WR星。母鸡2-113、母鸡3-1333、PMR 2和母鸡2-99的晚期[WC]型细胞核未检测到显著的RV变异性。在NGC 5315的[WC 4]核中发现了显著的大幅度变异。在NGC 5189的[WO 1]核中，我们发现了显著的周期性变化，揭示了一个具有$P_\mathrm{orb}=4.04\pm0.1$ d的近距离双星。我们测量了一个半振幅为$62.3\pm1.3$ km s的$^{-1}$，给出了一个伴星质量为$m_2\ge0.5$ $M_\odot$或$m_2=0.84$ $M_\odot$（假设是$i=45^\circ$）。最合理的伴生类型是在弗莱明1中发现的大规模WD。NGC 5189壮观的星云形态非常符合最近发现的后CE PNe的模式，其主要的低电离结构（例如NGC 6326）和准直流出（例如弗莱明1）。4.04 d的轨道周期非常长，这可能是一次性的（例如NGC 2346），或者它可能表明在相对较宽的轨道上有相当数量的[WR]双星和大质量的WD伴星，这可能是受到强[WR]风的影响。

英文摘要：

The formation of Wolf-Rayet central stars of planetary nebulae ([WR] CSPNe) whose spectroscopic appearance mimics massive WR stars remains poorly understood. Least understood is the nature and frequency of binary companions to [WR] CSPNe that may explain their H-deficiency. We have conducted a systematic radial velocity (RV) study of 6 [WR] CSPNe to search for post-common-envelope (post-CE) [WR] binaries. We used a cross-correlation method to construct the RV time-series as successfully done for massive close binary WR stars. No significant RV variability was detected for the late-[WC] type nuclei of Hen 2-113, Hen 3-1333, PMR 2 and Hen 2-99. Significant, large-amplitude variability was found in the [WC4] nucleus of NGC 5315. In the [WO1] nucleus of NGC 5189 we discovered significant periodic variability that reveals a close binary with $P_\mathrm{orb}=4.04\pm0.1$ d. We measured a semi-amplitude of $62.3\pm1.3$ km s$^{-1}$ that gives a companion mass of $m_2\ge0.5$ $M_\odot$ or $m_2=0.84$ $M_\odot$ (assuming $i=45^\circ$). The most plausible companion type is a massive WD as found in Fleming 1. The spectacular nebular morphology of NGC 5189 fits the pattern of recently discovered post-CE PNe extremely well with its dominant low-ionisation structures (e.g. as in NGC 6326) and collimated outflows (e.g. as in Fleming 1). The anomalously long 4.04 d orbital period is either a once-off (e.g. NGC 2346) or it may indicate there is a sizeable population of [WR] binaries with massive WD companions in relatively wide orbits, perhaps influenced by interactions with the strong [WR] wind.

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