发表机构
South African Astronomical Observatory; Southern African Large Telescope; Sternberg Astronomical Institute, Lomonosov Moscow State University（南非天文台; 南方大型望远镜; 莫斯科国立大学列别杰夫天体物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用SALT望远镜长缝光谱证实ESO 428−05的双极结构，测得环与极向外流的运动学年龄分别为1.5×10⁴年和(3–4)×10⁴年，并给出19个区域的化学丰度。
AI 中文摘要
本文报道了对双极行星状星云 ESO 428−05 进行详细长缝光谱观测的结果。观测使用南非大望远镜（SALT）上的设施光谱仪 RSS 完成。星云的总测量延展范围约为 55″，沿狭缝的运动学特征直接证实了其双极结构。星云相对于视线的倾角估计为 i≈45°。我们测量了两种形态结构的运动学年龄：膨胀环以及垂直于环方向的极向外流。前者的年龄约为 1.5×10⁴ 年，后者的年龄约为 (3–4)×10⁴ 年，即极向外流比中心环年老 2–3 倍。这两个年龄的比值不依赖于所采用的距离。ESO 428−05 的加权平均日心速度为 V_hel=74.7±1.6 km/s。我们在星云长轴方向、跨度 40″ 的范围内，对 19 个区域（即 ESO 428−05 的不同形态部分）获得了化学丰度。丰度采用 T_e 方法推导，其中电子温度直接根据测得的微弱极光发射线 [O III] λ4363 Å 和 [N II] λ5755 Å 计算。我们确定了 O、N、Ne、S、Ar、Cl 和 He 的丰度。尽管存在显著的分层现象，但沿狭缝测得的丰度可视为近似恒定。
英文摘要
The results of detailed long-slit spectroscopy of the bipolar planetary nebula \ESO\ are presented. The observations were obtained with the facility spectrograph RSS of the SALT telescope. The total measured extent of the nebula reaches $\approx$55$^{\prime\prime}$, and the kinematics along the slit directly confirms its bipolar structure. The inclination of the nebula to the line of sight is estimated as $i\approx 45^{\circ}$, and the kinematic ages of two morphological structures are measured: the expanding ring and the polar outflow in the direction perpendicular to the ring. The age of the former is $\approx$1.5$\times$10$^4$~yr and that of the latter is $\approx$(3--4)$\times$10$^4$~yr, i.e. the polar outflow is 2--3 times older than the central ring. The ratio of these ages does not depend on the adopted distance. The weighted mean heliocentric velocity of \ESO\ is V$_{\rm hel}$=74.7$\pm$1.6~\kms. Chemical abundances are obtained for 19 regions along the major axis of the nebula, over an extent of 40$^{\prime\prime}$, i.e. for different morphological parts of \ESO. The abundances were derived with the T$_{\rm e}$--method, where the electron temperature was calculated directly using the measured faint auroral lines [\ion{O}{iii}]~$λ$4363~Å and [\ion{N}{ii}]~$λ$5755~Å. The abundances of O, N, Ne, S, Ar, Cl and He were determined. Despite a significant stratification, the measured abundances along the slit can be considered nearly constant.
CommentsAccepted to Astrophysical Bulletin, 16 pages, 6 figures, 5 tables
