论文标题
Cygnus X中电离气体的丝状结构
Filamentary structures of ionized gas in Cygnus X
论文作者
论文摘要
电离气体探测大型恒星对环境的影响。 Cygnus X区域（D〜1.5 kpc）是我们银河系中最庞大的恒星形成的恒星之一，其中Cyg OB2关联（3-5岁的Myr和Stellar Mass $ 2 \ times 10^{4} {4} $ M $ _ {\ odot} $）具有占主导地位的影响。我们使用低频阵列（Lofar）观察148 MHz的Cygnus X区域，并考虑图像反卷积期间的较短间距信息。与加拿大银河平面调查的数据一起，我们研究了$ 4^{\ circt} \ times 4^{\ circ} $（100 pc $ \ times $ 100 $ 100 pc）在2'（0.9 pc）下，低密度离子化气体的形态，分布和物理条件（100 pc $ \ times $ 100 pc）。分析区域的银河无线电发射几乎完全是148 MHz的热（免费），发射量为$ 10^3 <em〜 {\ rm [pc〜cm^{ - 6}]} <10^6 $。由于丝状结构是排放的重要特征，因此我们使用分散和丝状结构来识别丝状脊并表征其径向（$ em $）概况。径向配置文件的分布的特征宽度为4.3 PC，峰值$ em $ $ $ $ $ $ $ $ $的幂律分布（$β= -1.8 \ pm 0.1 $）降至4200 pc cm $^{ - 6} $。丝状结构的电子密度从$ 10 <n_e〜 {\ rm [cm^{ - 3}]} <400 $，中位数为35 cm $ $^{ - 3} $，非常类似于[n ii]电离气体的[n ii]。 CYG OB2最多可能会在丝中的总电离气体和电离气体电离的最多电离。超过一半的丝状结构可能是光蒸发表面流入周围的分散（〜5 cm $^{ - 3} $）介质。但是，对于所有电离气脊而言，可能并非如此。电离气体分布的特征宽度指向CYG OB2的恒星风，从而通过扫描的离子气体或消散的湍流产生了离子丝的一部分。
Ionized gas probes the influence of massive stars on their environment. The Cygnus X region (d~1.5 kpc) is one of the most massive star forming complexes in our Galaxy, in which the Cyg OB2 association (age of 3-5 Myr and stellar mass $2 \times 10^{4}$ M$_{\odot}$) has a dominant influence. We observe the Cygnus X region at 148 MHz using the Low Frequency Array (LOFAR) and take into account short-spacing information during image deconvolution. Together with data from the Canadian Galactic Plane Survey, we investigate the morphology, distribution, and physical conditions of low-density ionized gas in a $4^{\circ} \times 4^{\circ}$ (100 pc $\times$ 100 pc) region at a resolution of 2' (0.9 pc). The Galactic radio emission in the region analyzed is almost entirely thermal (free-free) at 148 MHz, with emission measures of $10^3 < EM~{\rm[pc~cm^{-6}]} < 10^6$. As filamentary structure is a prominent feature of the emission, we use DisPerSE and FilChap to identify filamentary ridges and characterize their radial ($EM$) profiles. The distribution of radial profiles has a characteristic width of 4.3 pc and a power-law distribution ($β= -1.8 \pm 0.1$) in peak $EM$ down to our completeness limit of 4200 pc cm$^{-6}$. The electron densities of the filamentary structure range from $10 < n_e~{\rm[cm^{-3}]} < 400$ with a median value of 35 cm$^{-3}$, remarkably similar to [N II] surveys of ionized gas. Cyg OB2 may ionize at most two-thirds of the total ionized gas and the ionized gas in filaments. More than half of the filamentary structures are likely photoevaporating surfaces flowing into a surrounding diffuse (~5 cm$^{-3}$) medium. However, this is likely not the case for all ionized gas ridges. A characteristic width in the distribution of ionized gas points to the stellar winds of Cyg OB2 creating a fraction of the ionized filaments through swept-up ionized gas or dissipated turbulence.
