Using 3D numerical hydrodynamical simulations we show that a type Ia supernova (SN Ia) explosion inside a planetary nebula (PN) can explain the observed shape of the G1.9+0.3 supernova remnant (SNR) and its X-ray morphology. The SNR G1.9+0.3 morphology can be generally described as a sphere with two small and incomplete lobes protruding on opposite sides of the SNR, termed "ears", a structure resembling many elliptical PNe. Observations show the synchrotron X-ray emission to be much stronger inside the two ears than in the rest of the SNR. We numerically show that a spherical SN Ia explosion into a circumstellar matter (CSM) with the structure of an elliptical PN with ears and clumps embedded in the ears can explain the X-ray properties of SNR G1.9+0.3. While the ejecta has already collided with the PN shell in most of the SNR and its forward shock has been slowed down, the ejecta is still advancing inside the ears. The fast forward shock inside the ears explains the stronger X-ray emission there. SN Ia inside PNe (SNIPs) seem to comprise a non-negligible fraction of resolved SN Ia remnants.
The post-common-envelope binary central star of the planetary nebula PN G283.7-05.1: A possible post-red-giant-branch planetary nebula central star
我们在行星状星云PN G 283.7 $-$ 05.1中发现并描述了共包层后中心恒星系统。作为POPIPlaN巡天的一部分拍摄的深层图像显示，该星云可能具有类似于其他后共包络行星状星云的双极形态。同时光和径向速度曲线模型显示，新发现的双星系统包括一个高辐射，M型主序星在5.9小时的轨道与热前白矮星。星云的前身质量特别低，约为0.4 M $_\odot$，这使得PN G 283.7 $-$ 05.1成为少数几个候选行星状星云之一，它们是在红巨星分支上的共同包络事件的产物。除了它的低质量，模型的温度，表面重力和光度都被发现是一致的观察到的恒星和星云的光谱，通过比较与模型的大气和光电离建模。然而，星云中心恒星的高温（T $_\mathrm{eff}\sim$ 95 kK）和高光度与后RGB演化轨迹并不一致。
Observations of the planetary nebula RWT 152 with OSIRIS/GTC
RWT 152是少数几个已知的行星状星云之一，其中心恒星是sdO。我们提出了亚角秒红色可调谐滤波器Halpha成像和中等分辨率，长缝光谱的RWT 152获得与OSIRIS/GTC的目的是分析其属性。这张Halalpha图像显示了一个双极星云，有一个明亮的赤道区域和主叶中的多个气泡。一个微弱的圆形光晕围绕着主星云。星云光谱显示出一个非常低激发态的星云，有来自H^+、He^+和双电离金属的微弱发射线，除了极微弱的[NII]6584发射线外，没有来自中性和单电离金属的发射线。如果RWT 152是一个密度受限的行星状星云，那么这些光谱就可以得到解释。在RWT 152中获得了低的S、O、Ar、N和Ne的星云化学丰度，这与导出的高特有速度（$\sim$ 92-131 km s $^{-1}$）一起表明该天体是一个晕行星状星云。现有数据与RWT 152一致，RWT 152是从在贫金属环境中形成的低质量前体（$\sim$ 1 M $_{\odot}$）演变而来的。
