arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1105.0045astro-ph.EP
收藏

TW Hya盘的光蒸发风

The Photoevaporative Wind from the Disk of TW Hya

I. Pascucci, M. Sterzik, R. D. Alexander, S. H. P. Alencar, U. Gorti, D. Hollenbach, J. Owens, B. Ercolano, S. Edwards

备注：
Accepted for publication in ApJ
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

由中心恒星驱动的光蒸发被认为是分散行星形成的星周尘埃和气体的普遍而重要的机制。在这里，我们提出了一个详细的研究周围的恒星TW Hya的拱盘，并提供观测限制其光蒸发风。我们在[Ne II] 12.81 μm谱线上的新的高分辨率（R ~ 30，000）中红外光谱证实了这种气体诊断跟踪了距离恒星10 AU以内的非束缚风分量。根据谱线轮廓的蓝移和不对称性，我们估计大部分（>80%）的[Ne II]辐射来自于盘半径，其中中平面对于红移的流出气体是光学厚的，这意味着超出了从其他观测推断的1或4AU尘埃边缘。我们重新分析高分辨率（R ~ 48000）档案光学光谱，寻找额外的过渡，可能会跟踪光蒸发流。与[Ne II]线不同，OI，SII和MgI的光学禁戒线以恒星速度为中心，并具有对称轮廓。这些线可以跟踪光蒸发流的唯一方法是，如果它们出现在一个磁盘区域物理上不同于跟踪的[Ne II]线，特别是从光学薄灰尘间隙内。然而，这些线的小的（~10 km/s）半高宽表明，在光学波长处追踪的大部分发射气体是束缚在系统上的，而不是未束缚的。我们讨论了我们的研究结果的影响，行星引起的与光蒸发引起的差距。

英文摘要：

Photoevaporation driven by the central star is expected to be a ubiquitous and important mechanism to disperse the circumstellar dust and gas from which planets form. Here, we present a detailed study of the circumstellar disk surrounding the nearby star TW Hya and provide observational constraints to its photoevaporative wind. Our new high-resolution (R ~ 30,000) mid-infrared spectroscopy in the [Ne II] 12.81 μm line confirms that this gas diagnostic traces the unbound wind component within 10AU from the star. From the blueshift and asymmetry in the line profile, we estimate that most (>80%) of the [Ne II] emission arises from disk radii where the midplane is optically thick to the redshifted outflowing gas, meaning beyond the 1 or 4AU dust rim inferred from other observations. We re-analyze high-resolution (R ~ 48, 000) archival optical spectra searching for additional transitions that may trace the photoevaporative flow. Unlike the [Ne II] line, optical forbidden lines from OI, SII, and MgI are centered at the stellar velocity and have symmetric profiles. The only way these lines could trace the photoevaporative flow is if they arise from a disk region physically distinct from that traced by the [Ne II] line, specifically from within the optically thin dust gap. However, the small (~10 km/s) FWHM of these lines suggest that most of the emitting gas traced at optical wavelengths is bound to the system rather than unbound. We discuss the implications of our results for a planet-induced versus a photoevaporation-induced gap.

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。

↑