利用阿塔卡马大型毫米波/亚毫米波阵列1波段甲醇谱线观测探测V883 Ori星系盘的最内层区域
Probing the Innermost Region of the V883 Ori Disk Using ALMA Band 1 Methanol Line Observations
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中文总结 AI 辅助
该研究利用阿塔卡马大型毫米波/亚毫米波阵列1波段观测V883 Ori星系盘甲醇发射线，通过拟合谱线轮廓得出径向强度分布，发现盘最内层有大量气态甲醇，证明了（亚）厘米观测对探测星系盘内层不透明区域的能力，为后续观测奠定基础。
中文摘要 AI 辅助
原行星盘中主要挥发性物质的雪线在尘埃演化和向新生行星系统的挥发性物质输送中起着关键作用。本文报告了阿塔卡马大型毫米波/亚毫米波阵列1波段（约7.5毫米）对FU - Ori型恒星V883 Ori周围星系盘中甲醇（CH₃OH）发射线的观测，该星系盘中吸积爆发加热了星系盘且大部分冰已升华。我们以约0.2角秒的角分辨率探测到三条CH₃OH发射线。堆叠的CH₃OH图像呈现出中心峰值形态，与之前显示中心凹陷的（亚）毫米观测结果形成对比。通过拟合径向分辨的谱线轮廓，我们得出CH₃OH发射的径向强度分布，发现在约40天文单位处有陡峭增加。在约10天文单位处，CH₃OH柱密度至少达到约10¹⁹ - 10²⁰厘米⁻²。这提供了直接证据，表明星系盘最内层区域存在大量温暖气态甲醇，其发射在之前的（亚）毫米观测中因尘埃发射光学厚度大而被抑制。强度分布的陡峭增加可能表明中平面的CH₃OH雪线位于约30 - 55天文单位处，或者鉴于发射可能光学厚度大，CH₃OH发射追踪了温度结构。我们的结果证明了（亚）厘米观测在探测星系盘最内层不透明区域的能力和重要性，为未来利用即将到来的设施进行观测铺平了道路。
英文摘要
The snowlines of major volatiles in protoplanetary disks play a pivotal role in dust evolutions and volatile delivery to nascent planetary systems. In this paper, we report the Atacama Large Millimeter/submillimeter Array Band 1 ($\approx7.5\,\mathrm{mm}$) observations of methanol (CH$_3$OH) emission lines in the disk around the FU-Ori type star V883 Ori, where accretion outburst heats the disk and the majority of ices has sublimated. We detect three CH$_3$OH emission lines at an angular resolution of $\approx0.\!\!^{\prime\prime}2$. The stacked CH$_3$OH image exhibits a centrally-peaked morphology in contrast to the previous (sub-)mm observations that show a central depression. By fitting radially-resolved line profiles, we derive the radial intensity profile of the CH$_3$OH emission where we find a steep increase at $\lesssim40\,\mathrm{au}$. The column density of CH$_3$OH reaches at least $\sim10^{19}\mathrm{-}10^{20}\,\mathrm{cm^{-2}}$ at $\sim10\,\mathrm{au}$. This provides direct evidence that a significant amount of warm gaseous methanol is present in the innermost region of the disk where its emission has been suppressed in previous (sub-)mm observations due to the optically thick dust emission. The steep increase in the intensity profile may indicate that the CH$_3$OH snowline in the midplane is located at $\sim30\mathrm{-}55\,\mathrm{au}$, or that the CH$_3$OH emission traces the temperature structure given that the emission is likely optically thick. Our results demonstrate the capability and significance of (sub-)cm observations in probing the innermost opaque region of disks, paving the way for the future observations with upcoming facilities.
