Seeding the Galactic Centre gas stream: gravitational instabilities set the initial conditions for the formation of protocluster clouds
Seeding the Galactic Centre gas stream: gravitational instabilities set the initial conditions for the formation of protocluster clouds
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银河系中心气流的播种：引力不稳定性为原星团云的形成设定了初始条件
DOI：
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
J. Kruijssen
中科院分区：
文献类型：
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作者：
J. Henshaw;S. Longmore;J. Kruijssen;J. Kruijssen
中央分子带(CMZ)内恒星的形成可能与气体的轨道动力学密切相关。最近的模型表明，尘脊分子云(从G0.253+0.016到SGRB2)内的恒星形成遵循一个演化的时间序列，由它们在前一个中心附近通过期间的潮汐压缩触发。鉴于这些云最有可能是下一代大质量恒星和极端星团的先驱，这种情况将对限制恒星形成的时间演化产生深远的影响。在这封信中，我们寻找原星系团云的初始条件，重点是位于近心上游的气体的运动学。我们在空间中观测到了一个高度规则的波纹速度场，波幅和波长分别为：L，vRmLSR=3.7，Pm，0.1kms值-1和I值=22.5，Pm0.1，pc。速度的极值与一系列质量大($SIM10^{4}$M$\ODOT}$)和致密($R_(Rm)eq}\SIM2$PC)、准规则间隔($SIM8$PC)的分子云有关。波纹波长和云间距分别与预测的Toomre($sim17$PC)和Jeans($SIM6$PC)长度非常接近。我们得出结论，引力不稳定性正在推动银河系中心气流中分子云的凝聚。此外，我们推测这些种子是尘脊分子云的历史类比，代表了CMZ中恒星和星团形成的初始条件。
Star formation within the Central Molecular Zone (CMZ) may be intimately linked to the orbital dynamics of the gas. Recent models suggest that star formation within the dust ridge molecular clouds (from G0.253+0.016 to Sgr B2) follows an evolutionary time sequence, triggered by tidal compression during their preceding pericentre passage. Given that these clouds are the most likely precursors to a generation of massive stars and extreme star clusters, this scenario would have profound implications for constraining the time-evolution of star formation. In this Letter, we search for the initial conditions of the protocluster clouds, focusing on the kinematics of gas situated upstream from pericentre. We observe a highly-regular corrugated velocity field in $\{l,\,v_{\rm LSR}\}$ space, with amplitude and wavelength $A=3.7\,\pm\,0.1$ kms$^{-1}$ and $\lambda_{\rm vel, i}=22.5\,\pm\,0.1$ pc, respectively. The extremes in velocity correlate with a series of massive ($\sim10^{4}$M$_{\odot}$) and compact ($R_{\rm eq}\sim2$ pc), quasi-regularly spaced ($\sim8$ pc), molecular clouds. The corrugation wavelength and cloud separation closely agree with the predicted Toomre ($\sim17$ pc) and Jeans ($\sim6$ pc) lengths, respectively. We conclude that gravitational instabilities are driving the condensation of molecular clouds within the Galactic Centre gas stream. Furthermore, we speculate these seeds are the historical analogue of the dust-ridge molecular clouds, representing the initial conditions of star and cluster formation in the CMZ.
影响因子：
4.8
作者：
Henshaw, J. D.;Longmore, S. N.;Zhang, Q.
通讯作者：
Zhang, Q.