The Morphology and Kinematics of the Complex Polypolar Planetary Nebula NGC 2440
The Morphology and Kinematics of the Complex Polypolar Planetary Nebula NGC 2440
复制标题
复杂多极行星状星云 NGC 2440 的形态和运动学
DOI：
--
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
A. J. Holloway
中科院分区：
文献类型：
--
作者：
J. López;J. Meaburn;M. Bryce;A. J. Holloway
利用曼彻斯特中阶梯光栅光谱仪与行星状星云 NGC 2440 上空的 2.1 m San Pedro Mártir 望远镜相结合，获得了 Hα、[N II] 6584 Å 和 [O III] 5007 Å 线的空间分辨剖面。将所得的位置-速度 (PV) 阵列与地面和 HST 档案图像进行比较，揭示了该区域中普遍存在的复杂结构。对象。这项工作代表了 NGC 2440 的首次详细运动学研究。正如从具有不同准直度的双极、旋转、间歇性流出所预期的那样，几个双极结构显示出在距核心不同的位置角度出现。线分裂在西部和东部主瓣中分别达到主峰到峰间隔 175 km s-1 和 145 km s-1。复杂剖面的 FWZI 值的范围在核心附近为 250 km s-1，在外部区域为 150 km s-1。星云核心被发现是一个以≥22 km s-1径向膨胀的环形体，NGC 2440的系统日心径向速度被发现为65 km s-1。当与角膨胀上限的现有测量相结合，并假设中心环形轴在天空平面上倾斜 40° 时，膨胀速度的下限意味着到 NGC 2440 的距离≥1.45 kpc。令人费解的运动学特征是微弱的速度分量，相对于最亮两端突出结的系统径向速度，以 150 km s-1 的径向速度差后退。双极配置。来自明亮星云核心的线轮廓结中的尘埃散射可能是对这种奇怪现象的解释。
Spatially resolved profiles of the Hα, [N II] 6584 Å, and [O III] 5007 Å lines have been obtained with the Manchester echelle spectrometer combined with the 2.1 m San Pedro Mártir telescope over the planetary nebula NGC 2440. The resulting position-velocity (PV) arrays are compared with ground-based and HST archival imagery, revealing the complex structure that prevails in this object. This work represents the first detailed kinematical study of NGC 2440. Several bipolar structures are shown to be emerging at different position angles from the core, as expected from bipolar, rotating, episodic outflows with different degrees of collimation. Line splitting reaches main peak to peak separations of 175 km s-1 and 145 km s-1 in the western and eastern main lobes, respectively. The FWZI values of the complex profiles span a range of 250 km s-1 near the core and 150 km s-1 in the outer regions. The nebular core is found to be a toroid expanding radially at ≥22 km s-1, and the systemic heliocentric radial velocity of NGC 2440 is found to be 65 km s-1. When combined with existing measurements of the upper limit to the angular expansion, and assuming a tilt for the axis of the central toroid of 40° in the plane of the sky, this lower limit for the expansion velocity implies a distance of ≥1.45 kpc to NGC 2440. Puzzling kinematical features are the faint velocity components receding with radial velocity differences of 150 km s-1 with respect to the systemic radial velocity from prominent knots at both ends of the brightest bipolar configuration. Scattering by dust in these knots of the line profiles from the bright nebular core is a likely explanation for this curious phenomenon.