标题： 紧凑行星状星云 MaC 2-1 和 Sp 4-1：光致电离模型与尘埃特性 显示英文标题

标题： Compact planetary nebulae MaC 2-1 and Sp 4-1: Photoionization models and dust characteristics

摘要： 我们研究了行星状星云（PNe）MaC 2-1和Sp 4-1的特性。 我们使用了在2米口径喜马拉雅查拉纳望远镜上获取的光学光谱、斯皮策太空望远镜的中红外（mid-IR）光谱、哈勃太空望远镜（HST）图像以及红外测光数据。 这些PNe之前尚未被详细研究过。 这两个PNe都属于低至中激发类。 MaC 2-1显示出硅碳化物（SiC）和硫化镁（MgS）尘埃的存在。 Sp 4-1则包含多环芳烃（PAH）分子。 我们通过光学和中红外发射线的流量获得了PNe的等离子体性质。 我们构建了PNe的光致游离模型，用于自洽地估算与中心恒星和星云相关的物理参数，包括星云丰度。 通过对红外数据的建模，我们获得了星云中形成的尘埃和分子的特性。 根据我们的研究，MaC 2-1和Sp 4-1的前身恒星质量分别约为1.2和1.55 $M_{\sun}$，并且它们似乎都诞生于金属贫乏的环境。 两者都是遥远的PNe，MaC 2-1和Sp 4-1的估计距离分别为16千秒差距和18千秒差距。 显示英文摘要

摘要： We study the characteristics of planetary nebulae (PNe), MaC 2-1 and Sp 4-1. We use our optical spectra taken at 2 m Himalayan Chandra Telescope, Spitzer mid-infrared (mid-IR) spectra, HST images, and IR photometric data. These PNe have not been individually studied in details earlier. Both the PNe are in the low- to moderate-excitation class. MaC 2-1 shows the presence of silicon carbide (SiC) and magnesium sulphide (MgS) dust. Sp 4-1 hosts polycyclic aromatic hydrocarbon (PAH) molecules. We obtain plasma properties of the PNe from the optical and mid-IR emission line fluxes. We compute photoionization models of the PNe for self-consistent estimation of physical parameters associated with the central star and the nebula, including nebular abundances. From the modelling of the IR data, we obtain the characteristics of dust and molecules formed in the nebulae. From our study, we estimate that the progenitors of MaC 2-1 and Sp 4-1 had masses of 1.2 and 1.55 $M_{\sun}$, respectively, and both of them seem to have born in metal poor environment. Both are distant PNe, with the estimated distances of 16 and 18 kpc for MaC 2-1 and Sp 4-1, respectively.