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arXiv 1808.00992astro-ph.SRastro-ph.HE
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来自海山二大爆发高原的光回波揭示了一个两阶段的冲击动力事件

Light-echoes from the plateau in Eta Carinae's Great Eruption reveal a two-stage shock-powered event

Nathan Smith, Jennifer E. Andrews, Armin Rest, Federica B. Bianco, Jose L. Prieto, Tom Matheson, David J. James, R. Chris Smith, Giovanni Maria Strampelli, A. Zenteno

摘要:

我们提出了多历元测光和光谱的光回波从埃塔船底座的19世纪大爆发。回声显示了十年来的稳定下降,采样了19世纪50年代的火山爆发高原。光谱表明,整体外流速度增加,从150公里/秒的早期,高达600公里/秒的高原。后来的阶段也发展出非常宽的发射翼,表明质量加速到10,000 km/s以上。与其他线索一起,这为爆炸性喷射提供了直接证据。这伴随着从窄吸收线到发射线的过渡,通常具有宽的天鹅座P轮廓。这些变化意味着1845年前的光度峰值与1850年代的平稳期不同。这种变化的主要原因可能是激波相互作用在平台区占主导地位。eta Car的光谱演化与UGC 2773-OT非常相似,具有明显的激波相互作用特征。我们对eta Car的喷发提出了一个两阶段的设想:(1)在喷发前的几十年里,由产生密集赤道流出的二元相互作用驱动的缓慢流出,然后是(2)驱动CSM相互作用的爆炸性能量注入,为高原提供动力,并将较慢的CSM扫入成为Homunculus的快速壳层。我们将讨论这个序列如何可能产生于一个三重系统中的恒星合并,留下今天看到的偏心双星。这给出了一个自洽的方案,可以解释在很宽的初始质量范围内的相互作用瞬态。

英文摘要:

We present multi-epoch photometry and spectroscopy of a light echo from eta Carinae's 19th century Great Eruption. This echo shows a steady decline over a decade, sampling the 1850s plateau of the eruption. Spectra show the bulk outflow speed increasing from 150 km/s at early times, up to 600 km/s in the plateau. Later phases also develop remarkably broad emission wings indicating mass accelerated to more than 10,000 km/s. Together with other clues, this provides direct evidence for an explosive ejection. This is accompanied by a transition from narrow absorption lines to emission lines, often with broad P Cygni profiles. These changes imply that the pre-1845 luminosity spikes are distinct from the 1850s plateau. The key reason for this change may be that shock interaction dominates the plateau. The spectral evolution of eta Car closely resembles that of UGC2773-OT, which had clear signatures of shock interaction. We propose a 2-stage scenario for eta Car's eruption: (1) a slow outflow in the decades before the eruption, driven by binary interaction that produced a dense equatorial outflow, followed by (2) explosive energy injection that drove CSM interaction, powering the plateau and sweeping slower CSM into a fast shell that became the Homunculus. We discuss how this sequence could arise from a stellar merger in a triple system, leaving the eccentric binary seen today. This gives a self-consistent scenario that may explain interacting transients across a wide range of initial mass.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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