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arXiv 1004.4971astro-ph.SRastro-ph.GA
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行星状星云Milky Way隆起中星云壳层运动的演化

The Evolution of the Kinematics of Nebular Shells in Planetary Nebulae in the Milky Way Bulge

M. G. Richer, J. A. López, Ma. -T. García-Díaz, D. M. Clark, M. Pereyra, E. Díaz-Méndez

摘要:

我们利用曼彻斯特中阶梯摄谱仪在圣佩德罗山国家天文台(OAN-SPM)获得的光谱资料,研究了银河系凸起中两组行星状星云的[ \ion{O}{3} ] $λ$ 5007和H $α$谱线的线宽。第一个样本包括在其演变的早期对象,具有高H $β$光度,但[ \ion{O}{3} ] $λ5007/\mathrm Hβ< 3$。第二个样本包括处于演化后期的对象,具有\ion{He}{2} $λ4686/\mathrm Hβ> 0.5$。这些行星状星云代表了Richer et al.(2008)研究对象之前和之后的演化阶段。我们的行星状星云样本具有弱的[ \ion{O}{3} ] $λ$ 5007,其线宽分布与AGB星包层膨胀速度的分布相似,并且与Richer等人(2008)研究的演化程度较低的天体相比,其线宽分布系统性地降低。具有强\ion{He}{2} $λ4686$的样品的线宽分布与Richer等人(2008)的更进化的物体的线宽分布无法区分,但是角尺寸的分布系统地更大,因此它们显然更进化。这些数据和Richer et al.(2008)的数据形成了一个来自银河系行星状星云的同质样本,从最早的演化阶段直到中央恒星的核燃烧停止。它们证实了行星状星云流体动力学模型的长期预测,其中星云壳的运动学是由中央恒星的演化驱动的。

英文摘要:

We study the line widths in the [\ion{O}{3}]$λ$5007 and H$α$ lines for two groups of planetary nebulae in the Milky Way bulge based upon spectroscopy obtained at the Observatorio Astronómico Nacional in the Sierra San Pedro Mártir (OAN-SPM) using the Manchester Echelle Spectrograph. The first sample includes objects early in their evolution, having high H$β$ luminosities, but [\ion{O}{3}]$λ5007/\mathrm Hβ< 3$. The second sample comprises objects late in their evolution, with \ion{He}{2} $λ4686/\mathrm Hβ> 0.5$. These planetary nebulae represent evolutionary phases preceeding and following those of the objects studied by Richer et al. (2008). Our sample of planetary nebulae with weak [\ion{O}{3}]$λ$5007 has a line width distribution similar to that of the expansion velocities of the envelopes of AGB stars, and shifted to systematically lower values as compared to the less evolved objects studied by Richer et al. (2008). The sample with strong \ion{He}{2} $λ4686$ has a line width distribution indistinguishable from that of the more evolved objects from Richer et al. (2008), but a distribution in angular size that is systematically larger and so they are clearly more evolved. These data and those of Richer et al. (2008) form a homogeneous sample from a single Galactic population of planetary nebulae, from the earliest evolutionary stages until the cessation of nuclear burning in the central star. They confirm the long-standing predictions of hydrodynamical models of planetary nebulae, where the kinematics of the nebular shell are driven by the evolution of the central star.

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