The Double-Degenerate Nucleus of the Planetary Nebula TS 01. A Close Binary Evolution Showcase
Gagik Tovmassian, Lev Yungelson, Thomas Rauch, Valery Suleimanov, Ralf Napiwotzki, Grazyna Stasinska, John Tomsick, Jorn Wilms, Christophe Morisset, Miriam Pena, Michael G. Richer
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Accepted for publication in Ap.J., 25 pages, 17 figures
We present a detailed investigation of SBS1150+599A, a close binary star hosted by the planetary nebula PN G135.9+55.9 (TS01, Stasinska et al, 2009). The nebula, located in the Galactic halo, is the most oxygen-poor one known to date and is the only one known to harbor a double degenerate core. We present XMM-Newton observations of this object, which allowed the detection of the previously invisible component of the binary core, whose existence was inferred so far only from radial velocity and photometric variations. The parameters of the binary system were deduced from a wealth of information via three independent routes using the spectral energy distribution (from the infrared to X-rays), the light and radial velocity curves, and a detailed model atmosphere fitting of the stellar absorption features of the optical/UV component. We find that the cool component must have a mass of 0.54+/-0.2 Msun, an average effective temperature, Teff, of 58000+/-3000 K, a mean radius of 0.43+/-0.3 Rsun, a gravity log g=5.0+/-0.3, and that it nearly fills its Roche lobe. Its surface elemental abundances are found to be: 12 + log He/H = 10.95+/-0.04 dex, 12 + log C/H = 7.20+/-0.3 dex, 12 + log N/H < 6.92 and 12 + log O/H < 6.80, in overall agreement with the chemical composition of the planetary nebula. The hot component has Teff = 160-180 kK, a luminosity of about ~10e4 Lsun and a radius slightly larger than that of a white dwarf. It is probably bloated and heated as a result of intense accretion and nuclear burning on its surface in the past. The total mass of the binary system is very close to Chandrasekhar limit. This makes TS01 one of the best type Ia supernova progenitor candidates. We propose two possible scenarios for the evolution of the system up to its present stage.
The outflows and 3D structure of NGC 6337, a planetary nebula with a close binary nucleus
NGC 6337是一个罕见的行星状星云，其中一个近距离双星核已被确定。星云的形态和发射线轮廓都是不寻常的，特别是后者。我们提出了一个彻底的映射的空间分辨，长缝阶梯光谱获得的星云，允许其复杂的运动学的详细特征。这些信息，连同窄带图像被用来产生一个三维模型的星云使用的代码形状。三维模型产生了一个缓慢膨胀的环形体，在其外围有很大的密度波动，被观察为彗星结。低电离的双极膨胀帽系统位于环形线圈外部。此外，一个扩展的高速和纤细的双极准直流出被发现出现从核心和急剧弯曲在相反的方向，一个行为，不能占纯磁发射和准直，除非流出的源是旋进或旋转，可以预期从一个密切的二元核。
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
The double-degenerate, super-Chandrasekhar nucleus of the planetary nebula Henize 2-428
行星状星云（PN）阶段是质量为1到8个太阳质量（M $_\odot$）的恒星的最终命运。虽然已经提出了一些涉及二元相互作用的机制，但对其复杂形态的起源知之甚少。在密近双星系统中，当主星在渐近巨星分支（AGB）阶段膨胀时，轨道间隔足够短，足以填满其洛希瓣。多余的物质最终形成了一个共同的信封（CE）周围的两颗恒星。然后，拖曳力将导致包络被弹出到赤道与系统轨道平面重合的双极PN中。两颗恒星都喷射出它们的包层并向白矮星（WD）阶段演化的系统被称为双简并星。在这里，我们报告说，Henize 2-428有一个双简并的核心与一个合并的质量明确地高于1.4 M $_\odot$的Escherasekhar限制。根据其短的轨道周期（4.2小时）和总质量（1.76 M $_\odot$），该系统应该在7亿年内合并，引发Ia型超新星（SN Ia）事件。这一发现支持了Ia超新星形成的双简并、超钱德拉塞卡进化通道。
Variability of Central Stars of Planetary Nebulae with the Zwicky Transient Facility. I. Methods, Short-Timescale Variables, Binary Candidates, and the Unusual Nucleus of WeSb 1
3-D modelling of the collimated bipolar outflows of compact planetary nebulae with WR-type central stars
我们提出了高分辨率，长狭缝光谱观测五个紧凑的（$\leq$ 10角秒）行星状星云位于靠近银河系的隆起区域，没有高空间分辨率的图像。这些数据来自圣佩德罗·马尔蒂尔银河系行星状星云运动学目录（López et al. 2012）。其中四个天体（M1 -32、M2 -20、M2 -31和M3 -15）的中心恒星为WR型，第五个天体（M2 -42）的核心为Wels型。这些观测结果揭示了在所有这些存在的密集和厚赤道环面状组件和高速，准直，双极流出。代码SHAPE是用来调查的主要形态运动学特征和再现的3-D结构，这些对象假设一个圆柱形的速度场的双极流出和同源膨胀法的环面/环组件。双极外流的反投影膨胀速度在65至200 km $\rm{s^{-1}}$的范围内，而环面/环组件显示出慢得多的膨胀速度，在15至25 km $\rm{s^{-1}}$的范围内。研究发现，这些行星状星云具有非常相似的结构成分，它们发射谱线的差异主要来自它们在天空中的不同投影。它们的形态运动学特征与WR型核的关系值得进一步研究。
Two hot pre-white dwarfs inside the red-giant-branch planetary nebula Pa 13 -- Double core evolution or common envelope-induced rejuvenation?
Zentrum für Astronomie der Universität Heidelberg, Landessternwarte（海德堡大学天文中心，兰德斯施特恩瓦尔特）；Instituto de Astrofísica de Canarias（加那利天体物理研究所）；Departamento de Astrofísica, Universidad de La Laguna（拉帕尔马大学天体物理学系）；Department of Physics and Astronomy, Valparaiso University（瓦尔帕莱索大学物理与天文学系）；Instituto de Astrofísica de La Plata, UNLP-CONICET（拉普拉塔天体物理研究所，UNLP-CONICET）；Institut für Physik und Astronomie, Universität Potsdam（波茨坦大学物理与天文学研究所）；Department of Astronomy, University of Geneva（日内瓦大学天文学系）
