论文标题

Elias 2-27 Protoplanetary磁盘垂直扩展和不对称的CN发射

Vertically extended and asymmetric CN emission in the Elias 2-27 protoplanetary disk

论文作者

Paneque-Carreño, T., Miotello, A., van Dishoeck, E. F., Pérez, L. M., Facchini, S., Izquierdo, A., Tychoniec, L., Testi, L.

论文摘要

Elias 2-27是一颗年轻的恒星,拥有一个延伸,明亮和倾斜的灰尘和气体磁盘。磁盘的倾斜度和极端爆炸使Elias 2-27成为研究分子垂直分布(尤其是CN)的理想目标。我们直接追踪Elias 2-27中CN的发射,并将其与先前发布的CO同位素数据进行比较。 CN $ n = 3-2 $排放以两种不同的过渡分析$ j = 7/2-5/2 $和$ j = 5/2-3/2 $,为此我们检测到两个超细群体过渡。 CN发射的垂直位置直接从通道图中追溯,遵循先前用于分析Elias 2-27的CO发射的几何方法。分析模型用于参数每个分子的垂直轮廓并研究每个示踪剂的程度,此外,我们计算柱密度和光学深度的径向谱。我们表明,Elias 2-27中CN和CO同位素的垂直位置是分层的,并且与热化学模型的预测一致。检测到CN的径向范围内的北/南方不对称,我们发现CN发射大部分是光学薄的,并且在$ z/r \ sim $ 0.5时垂直被垂直限制在薄板上。在内部磁盘中测量了10 $^{14} $ \,cm $^{ - 2} $的列密度,该圆盘的内部磁盘均降低至10 $^{12} $ \,cm $^{ - 2} $,对于南侧为10 $^{13} $ \,cm $^,cm $^,cm $^,cm $^{ - 2} $ nound Outsource。在Elias 2-27中,CN跟踪中平面上方的垂直升高区域,与$^{12} $ CO所追踪的区域非常相似。推断的CN属性与热化学磁盘模型一致,其中N与UV泵的H $ _2 $的反应启动了CN形成。观察到的北/南方不对称可能是由持续的中心或扭曲的内磁盘引起的。这项研究强调了追踪各种分子以限制磁盘物理条件的垂直位置的重要性。

Elias 2-27 is a young star that hosts an extended, bright and inclined disk of dust and gas. The inclination and extreme flaring of the disk make Elias 2-27 an ideal target to study the vertical distribution of molecules, particularly CN. We directly trace the emission of CN in Elias 2-27 and compare it to previously published CO isotopologue data. CN $N = 3-2$ emission is analyzed in two different transitions $J = 7/2 - 5/2$ and $J = 5/2 - 3/2$, for which we detect two hyperfine group transitions. The vertical location of CN emission is traced directly from the channel maps, following geometrical methods that have been previously used to analyze the CO emission of Elias 2-27. Analytical models are used to parametrize the vertical profile of each molecule and study the extent of each tracer, additionally we compute radial profiles of column density and optical depth. We show that the vertical location of CN and CO isotopologues in Elias 2-27 is layered and consistent with predictions from thermochemical models. A north/south asymmetry in the radial extent of CN is detected and we find that the CN emission is mostly optically thin and constrained vertically to a thin slab at $z/r \sim$0.5. A column density of 10$^{14}$\,cm$^{-2}$ is measured in the inner disk which for the north side decreases to 10$^{12}$\,cm$^{-2}$ and for the south side to 10$^{13}$\,cm$^{-2}$ in the outer regions. In Elias 2-27, CN traces a vertically elevated region above the midplane, very similar to that traced by $^{12}$CO. The inferred CN properties are consistent with thermo-chemical disk models, in which CN formation is initiated by the reaction of N with UV-pumped H$_2$. The observed north/south asymmetry may be caused by either ongoing infall or by a warped inner disk. This study highlights the importance of tracing the vertical location of various molecules to constrain the disk physical conditions.

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