论文标题
表征三维磁场，湍流和恒星形成区域L1688
Characterizing three-dimensional magnetic field, turbulence, and self-gravity in the star-forming region L1688
论文作者
论文摘要
分子云中三维磁场，湍流和自我实力的相互作用对于理解恒星形成至关重要，但到目前为止尚未解决。在这项工作中，我们瞄准了低质量恒星区域L1688，并使用$^{12} $ CO，$^{13} $ CO，C $^{18} $ O和H I的光谱排放以及偏光灰尘排放。为了获得磁场的3D方向，我们采用了新型的极化分数分析。在与戴维斯 - 奇德拉塞卡尔 - 费尔米（DCF）方法得出的天基（POS）磁场强度和新的差分测量分析（DMA）技术相结合时，我们介绍了L1688的三维磁场（包括其方向和强度）的首次测量。我们发现L1688的磁场具有两个统计上不同的倾斜角。低强度的尾部平均具有倾斜角$ \ off55^\ circ $，而中央密集团的倾斜度为$ \ of of of of $ \ oft30^\ circ $。我们发现总磁场强度的全局平均值为$ b _ {\ rm tot} \ oft135 $ ug，$ b _ {\ rm tot} \ lm tot} \ oft dma。我们使用速度梯度技术（VGT）来分离与L1688及其前景/背景相关的磁场的POS方向。磁场的方向在统计上是连贯的。 h $ _2 $列密度和VGT的概率密度函数表明，L1688可能会在大规模上进行重力收缩$ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ overtation。重力收缩主要沿磁场导致近似的幂律关系$ b _ {\ rm tot} \ propto n _ {\ rm h}^{1/2} $时，当体积密度$ n _ {\ rm h} $是小于$ 6.0 \ 6.0 \ times10^3 $ cm $ cm $ cm $ cm $ cm $ cm $ cm^}时。
Interaction of three-dimensional magnetic fields, turbulence, and self-gravity in the molecular cloud is crucial in understanding star formation but has not been addressed so far. In this work, we target the low-mass star-forming region L1688 and use the spectral emissions of $^{12}$CO, $^{13}$CO, C$^{18}$O, and H I, as well as polarized dust emissions. To obtain the 3D direction of the magnetic field, we employ the novel polarization fraction analysis. In combining with the plane-of-the-sky (POS) magnetic field strength derived from the Davis-Chandrasekhar-Fermi (DCF) method and the new Differential Measure Analysis (DMA) technique, we present the first measurement of L1688's three-dimensional magnetic field, including its orientation and strength. We find that L1688's magnetic field has two statistically different inclination angles. The low-intensity tail has an inclination angle $\approx55^\circ$ on average, while that of the central dense clump is $\approx30^\circ$. We find the global mean value of total magnetic field strength is $B_{\rm tot}\approx135$ uG from DCF and $B_{\rm tot}\approx75$ uG from DMA. We use the velocity gradient technique (VGT) to separate the magnetic fields' POS orientation associated with L1688 and its foreground/background. The magnetic fields' orientations are statistically coherent. The probability density function of H$_2$ column density and VGT reveal that L1688 is potentially undergoing gravitational contraction at large scale $\approx1.0$ pc and gravitational collapse at small scale $\approx0.2$ pc. The gravitational contraction mainly along the magnetic field results in an approximate power-law relation $B_{\rm tot}\propto n_{\rm H}^{1/2}$ when volume density $n_{\rm H}$ is less than approximately $6.0\times10^3$ cm$^{-3}$.
