Gaia DR1 Evidence of Disrupting the Perseus Arm
Gaia DR1 Evidence of Disrupting the Perseus Arm
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DOI：
10.3847/2041-8213/aaa839
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发表时间：
2017-12
期刊：
影响因子：
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通讯作者：
J. Baba;D. Kawata;N. Matsunaga;R. Grand;Jason A. S. Hunt
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文献类型：
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作者：
J. Baba;D. Kawata;N. Matsunaga;R. Grand;Jason A. S. Hunt
我们利用造父变星的精确测量距离和盖亚数据发布1的自行，利用造父变星变量发现了银河系英仙座臂破坏阶段的明显迹象。在英仙座臂1.5 kpc范围内的77颗造父变星的银河中心径向速度和旋转速度都与它们到英仙座臂轨迹的距离相关，因为与前侧相比，后侧旋转得更快，并且向内移动。我们还发现造父变星后缘的顶点偏差为负，为−27.°6 ± 2.°4，而太阳附近的顶点偏差为正。这是，据我们所知，第一个直接的证据表明，围绕英仙座臂的顶点偏差的影响，螺旋arm. We比较了这些观测趋势与我们的N-体/流体力学模拟的基础上的静态密度波螺旋的情况下，与那些基于瞬态动态螺旋的情况下。虽然我们的比较仅限于定性趋势，但它们强烈支持英仙座手臂处于短暂手臂的中断阶段的结论。
We have discovered a clear sign of the disruption phase of the Perseus arm in the Milky Way using Cepheid variables, taking advantage of the accurately measured distances of Cepheids and the proper motions from Gaia Data Release 1. Both the Galactocentric radial and rotation velocities of 77 Cepheids within 1.5 kpc of the Perseus arm are correlated with their distances from the locus of the Perseus arm, as the trailing side is rotating faster and moving inward compared to the leading side. We also found a negative vertex deviation for the Cepheids on the trailing side, −27.°6 ± 2.°4, in contrast to the positive vertex deviation in the solar neighborhood. This is, to our knowledge, the first direct evidence that the vertex deviation around the Perseus arm is affected by the spiral arm. We compared these observational trends with our N-body/hydrodynamics simulations based on a static density-wave spiral scenario and with those based on a transient dynamic spiral scenario. Although our comparisons are limited to qualitative trends, they strongly favor the conclusion that the Perseus arm is in the disruption phase of a transient arm.