Outer rotation curve of the Galaxy with VERA. III. Astrometry of IRAS 07427-2400 and test of the density-wave theory
Outer rotation curve of the Galaxy with VERA. III. Astrometry of IRAS 07427-2400 and test of the density-wave theory
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DOI：
10.1093/pasj/psv049
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发表时间：
2015-05
影响因子：
2.3
通讯作者：
N. Sakai;H. Nakanishi;M. Matsuo;N. Koide;Daisuke Tezuka;T. Kurayama;K. Shibata;Y. Ueno;M. Honma
中科院分区：
文献类型：
--
作者：
N. Sakai;H. Nakanishi;M. Matsuo;N. Koide;Daisuke Tezuka;T. Kurayama;K. Shibata;Y. Ueno;M. Honma
我们报道了IRA 07427-2400与VERA的三角视差为0.185$\pm$0.027 Ma，对应的距离为5.41kpc。这一结果与Choi等人得到的5.32$kpc的结果是一致的。(2014)在误差范围内。为了消除内部脉泽运动(例如随机运动)的影响，我们观测了与IRAS 07427-2400相关的6个脉泽特征，并通过平均这6个脉泽特征的自身运动来确定震源的系统自行。在赤道坐标下得到的自行为(MU_α)=($-1.79$\PM$0.32，2.60$\PM$0.17)，而Choi等人。(2014)显示($\MU_{\α}$cos$\DELTA$，$\MU_{\DELTA}$)=($-$2.43$\PM$0.02，2.49$\PM$0.09)mYR$^{-1}$具有一个脉泽特征。我们的天体测量结果将源头放在英仙座的臂上，这是银河系中距离最近的主臂。利用我们的结果和先前从英仙座臂观测得到的天体测量结果，我们对27个天体测量结果和基于密度波理论的分析气体动力学模型进行了直接(定量)比较，得到了两个结果。首先是由VLBI天体测量学确定的英仙座手臂的俯仰角，11.1美元\PM$1.4°，与螺旋势模型(可能由恒星追踪)确定的角度$\sim$20°不同。第二个是稠密气体区域与螺旋势模型底部之间的偏移量。VLBI天体测量学追踪到的致密气体区位于螺旋势模型的下游，这一点之前在附近的Egusa等人的宏伟设计的螺旋星系M51中得到了证实。(2011)。
We report the trigonometric parallax of IRAS 07427-2400 with VERA to be 0.185 $\pm$ 0.027 mas, corresponding to a distance of 5.41$^{+0.92}_{-0.69}$ kpc. The result is consistent with the previous result of 5.32$^{+0.49}_{-0.42}$ kpc obtained by Choi et al. (2014) within error. To remove the effect of internal maser motions (e.g., random motions), we observed six maser features associated with IRAS 07427-2400 and determined systematic proper motions of the source by averaging proper motions of the six maser features. The obtained proper motions are ($\mu_{\alpha}$cos$\delta$, $\mu_{\delta}$) = ($-$1.79 $\pm$ 0.32, 2.60 $\pm$ 0.17) mas yr$^{-1}$ in equatorial coordinates, while Choi et al. (2014) showed ($\mu_{\alpha}$cos$\delta$, $\mu_{\delta}$) = ($-$2.43 $\pm$ 0.02, 2.49 $\pm$ 0.09) mas yr$^{-1}$ with one maser feature. Our astrometry results place the source in the Perseus arm, the nearest main arm in the Milky Way. Using our result with previous astrometry results obtained from observations of the Perseus arm, we conducted direct (quantitative) comparisons between 27 astrometry results and an analytic gas dynamics model based on the density-wave theory and obtained two results. First is the pitch angle of the Perseus arm determined by VLBI astrometry, 11.1 $\pm$ 1.4 deg, differing from what is determined by the spiral potential model (probably traced by stars), $\sim$ 20 deg. The second is an offset between a dense gas region and the bottom of the spiral potential model. The dense gas region traced by VLBI astrometry is located downstream of the spiral potential model, which was previously confirmed in the nearby grand-design spiral galaxy M51 in Egusa et al. (2011).