A collimated jet of molecular gas from a star on the asymptotic giant branch
A collimated jet of molecular gas from a star on the asymptotic giant branch
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DOI：
10.1038/nature00788
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发表时间：
2002-06
期刊：
影响因子：
64.8
通讯作者：
H. Imai;K. Obara;P. Diamond;T. Omodaká;T. Sasao
中科院分区：
文献类型：
--
作者：
H. Imai;K. Obara;P. Diamond;T. Omodaká;T. Sasao
大约一个太阳质量的演化恒星通常是球对称的，但是它们在演化的下一阶段产生的行星状星云往往不表现出这种对称性。在距离行星状星云中心恒星约0.3秒差距的范围内，已经观测到了准直的“喷流”和物质外流，这些喷流的进动被认为可以解释观测到的不对称性。此外，最近的理论表明，磁场可以发射和准直这种射流。在这里，我们报告的检测准直和旋进射流的分子气体，跟踪水蒸气脉泽斑点Au 500天文单位（星星W 43 A在天鹰座。我们的结论是，喷流是在星星附近形成的，并推断拉长的行星状星云是在不到1,000年的短时期内由喷流形成的，当时星星从原行星状星云阶段过渡到行星状星云。
Evolved stars of about one solar mass are in general spherically symmetric, yet the planetary nebulae that they produce in the next phase of their evolution tend not to exhibit such symmetry. Collimated ‘jets’ and outflows of material have been observed,,,,up to ∼0.3 parsec from the central stars of planetary nebulae, and precession of those jets has been proposed to explain the observed asymmetries. Moreover, it has recently been shown theoretically that magnetic fields could launch and collimate such jets. Here we report the detection of a collimated and precessing jet of molecular gas that is traced by water-vapour maser spots ∼500 astronomical units (au) from the star W43A in Aquila. We conclude that the jet is formed in the immediate vicinity of the star, and infer that elongated planetary nebulae are formed by jets during the short period, of less than 1,000 years, when the star makes its transition through the proto-planetary nebula phase to become a planetary nebula.