arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2104.01377astro-ph.GA
收藏

由经典造父变星追踪的银河系旋臂片段：年龄不均匀性的影响

Segments of spiral arms of the Galaxy traced by classical Cepheids: Effects of age heterogeneity

Angelina V. Veselova, Igor' I. Nikiforov

备注：
18 pages
发表信息：
Research in Astronomy and Astrophysics, 2020, Volume 20, Issue 12, id.209
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

我们研究了银河系旋臂段的参数对经典造父变星年龄的依赖性。造父变星的目录（Mel'nik et al. 2015）被分为两个样本$-$相对年轻（$P>9^\text{d}$）和相对古老（$P<9^\text{d}$）的对象。螺旋结构的参数分别为两个样本，并共同为年轻和老对象跟踪的两个系统的段的组合确定。对于大多数段，它们的年轻对象和旧对象的参数显著不同。考虑到两个分段系统之间的差异，我们得到了估计$R_0$等于$7.23^{+0.19}_{-0.18}$ kpc，这在现代LMC校准中对应于$R_0={8.08^{+0.21}_{-0.20}}|_{\text{stat.}} {}^{+0.38}_{-0.36}|_{\text{cal.}}$ kpc的值。它示出的段之间的位移并没有减少到仅差旋转的效果。为了解释英仙座和人马座2段的物体的这种位移，我们对在银河系的平滑引力场中移动时段点位置的变化进行了动态建模。在螺旋模式旋转角速度为$Ω_{\text{p}} = 25.2 \pm 0.5$ km s $^{-1}$ kpc $^{-1}$（Dambis等人，2015年）的情况下，观测到的年轻和年老物体上的段之间的位移可以用径向速度为$u = 10 \pm1.5$ km s $^{-1}$的螺旋扰动幅度来解释。对于构造的双螺旋段系统，证明了在不确定度范围内，螺旋段内螺距角不变的假设和螺旋模式的极点位于银河系名义中心方向的假设与数据并不矛盾。

英文摘要：

We investigated the dependence of the parameters of the segments of spiral arms of the Galaxy on the age of classical Cepheids. The catalog of Cepheids (Mel'nik et al. 2015) was divided into two samples$-$relatively young ($P>9^\text{d}$) and relatively old ($P<9^\text{d}$) objects. The parameters of the spiral structure were determined both for two samples separately and jointly for the combination of two systems of segments traced by young and old objects. For most of the segments, their parameters for young and old objects differ significantly. Taking into account the difference between the two segment systems, we obtained the estimate $R_0$ equal to $7.23^{+0.19}_{-0.18}$ kpc, which in the modern LMC calibration corresponds to the value of $R_0={8.08^{+0.21}_{-0.20}}|_{\text{stat.}} {}^{+0.38}_{-0.36}|_{\text{cal.}}$ kpc. It is shown that the displacement between the segments is not reduced to the effect of differential rotation only. To interpret this displacement for objects of Perseus and Sagittarius-2 segments we carried out a dynamic modeling of the change in the position of the segment points when moving in the smooth gravitational field of the Galaxy. At the angular velocity of rotation of the spiral pattern $Ω_{\text{p}} = 25.2 \pm 0.5$ km s$^{-1}$ kpc$^{-1}$ (Dambis et al. 2015) the observed displacement between segments on young and old objects can be explained by the amplitude of spiral perturbations of the radial velocity of $u = 10 \pm1.5$ km s$^{-1}$. For the constructed double system of spiral segments, it is demonstrated that the assumption of constancy of the pitch angles within each segment and the assumption that the pole of the spiral pattern is in the direction of the nominal center of the Galaxy do not contradict the data within the range of uncertainty.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑