arXiv 0808.26672008-08-19astro-ph

行星状星云在Milky Way凸起中的星云壳层加速度

The Acceleration of the Nebular Shells in Planetary Nebulae in the Milky Way Bulge

Michael G. Richer, Jose Alberto Lopez, Margarita Pereyra, Hortensia Riesgo, Maria Teresa Garcia Diaz, Sol-Haret Baez

备注：: accepted for publication in Astrophysical Journal
DOI：: 10.1086/592737

摘要：

我们提出了一个系统的研究[ \ion{O}{3} ] $λ$ 5007和H $α$线的86个行星状星云在银河系隆起的基础上获得的光谱在\facility{Observatorio Astronómico Nacional in the Sierra San Pedro Mártir (OAN-SPM)}使用曼彻斯特Echelle摄谱仪的样品的线宽。行星状星云的选择是为了模拟明亮的河外行星状星云的样本。我们将行星状星云分成两个样本，其中包含较冷和较热的中心恒星，分别由H $α$光谱中\ion{He}{2} $λ$ 6560线的存在或不存在来定义。这种划分将更年轻和更进化的行星状星云的样本分开。具有较热中心恒星的行星状星云样本具有系统性的较大线宽、较大半径、较低电子密度和较低H $β$光度。这些参数在两个样本中的分布差异均超过99%的显著性水平。这些差异都与流体动力学模型的预期一致，但首次证实了银河系行星状星云的均匀和统计显著样本。我们解释这些差异的证据加速星云壳在早期演化的这些本质上明亮的行星状星云。与麦哲伦星云中的行星状星云一样，星云壳层的加速似乎是中心恒星演化的直接结果。

英文摘要：

We present a systematic study of line widths in the [\ion{O}{3}]$λ$5007 and H$α$ lines for a sample of 86 planetary nebulae in the Milky Way bulge based upon spectroscopy obtained at the \facility{Observatorio Astronómico Nacional in the Sierra San Pedro Mártir (OAN-SPM)} using the Manchester Echelle Spectrograph. The planetary nebulae were selected with the intention of simulating samples of bright extragalactic planetary nebulae. We separate the planetary nebulae into two samples containing cooler and hotter central stars, defined by the absence or presence, respectively, of the \ion{He}{2} $λ$6560 line in the H$α$ spectra. This division separates samples of younger and more evolved planetary nebulae. The sample of planetary nebulae with hotter central stars has systematically larger line widths, larger radii, lower electron densities, and lower H$β$ luminosities. The distributions of these parameters in the two samples all differ at significance levels exceeding 99%. These differences are all in agreement with the expectations from hydrodynamical models, but for the first time confirmed for a homogeneous and statistically significant sample of galactic planetary nebulae. We interpret these differences as evidence for the acceleration of the nebular shells during the early evolution of these intrinsically bright planetary nebulae. As is the case for planetary nebulae in the Magellanic Clouds, the acceleration of the nebular shells appears to be the direct result of the evolution of the central stars.

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