arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2103.00248astro-ph.GA
收藏

基于Gaia DR2星表造父变星的星系运动学分析

Analysis of galaxy kinematics based on Cepheids from the Gaia DR2 Catalogue

V. V. Bobylev, A. T. Bajkova, A. S. Rastorguev, M. V. Zabolotskikh

摘要:

为了构建银河系的旋转曲线,我们在很大程度上使用了盖亚DR 2星表中的经典造父变星的自行、惯性和视线速度。从文献数据中形成的工作样本包含大约800颗造父变星及其年龄估计。我们确定了银河系在太阳距离上的线自转速度为$V_0=240\pm3$ ~km s $^{-1}$。在这种情况下,从太阳到银河系旋转轴的距离为$R_0=8.27\pm0.10$ ~kpc。对年龄小于1.2亿年的造父变星的径向速度和剩余切向速度的谱分析表明,从目前和过去的数据中获得的螺旋密度波的参数估计接近。因此,对于四臂模式,波长$λ_{R,θ}$的值在[2.4--3.0] kpc范围内,俯仰角$i_{R,θ}$的值在[ $-13^\circ$,$-10^\circ$ ]范围内,径向和切向扰动的幅值分别为$f_R\sim12$ ~km s $^{-1}$和$f_θ\sim9$ ~km s $^{-1}$。年龄超过1.2亿年的造父变星的速度目前给出的波长为$λ_{R,θ}\sim5$ ~kpc。这个值与我们从年轻造父变星样本中获得的值有很大不同。分析旧造父变星的位置和速度,通过将它们的轨道在时间上向后积分来计算,使得有可能确定螺旋密度波的参数的显著更可靠的值:波长$λ_{R,θ}=2.7$ ~kpc,径向和切向扰动的幅度分别为$f_R=7.9$ ~km s $^{-1}$和$f_θ=5$ ~km s $^{-1}$。

英文摘要:

To construct the rotation curve of the Galaxy, classical Cepheids with proper motions, parallaxes and line-of-sight velocities from the Gaia DR2 Catalog are used in large part. The working sample formed from literature data contains about 800 Cepheids with estimates of their age. We determined that the linear rotation velocity of the Galaxy at a solar distance is $V_0=240\pm3$~km s$^{-1}$. In this case, the distance from the Sun to the axis of rotation of the Galaxy is found to be $R_0=8.27\pm0.10$~kpc. A spectral analysis of radial and residual tangential velocities of Cepheids younger than 120 Myr showed close estimates of the parameters of the spiral density wave obtained from data both at present time and in the past. So, the value of the wavelength $λ_{R,θ}$ is in the range of [2.4--3.0] kpc, the pitch angle $i_{R,θ}$ is in the range of [$-13^\circ$,$-10^\circ$] for a four-arm pattern model, the amplitudes of the radial and tangential perturbations are $f_R\sim12$~km s$^{-1}$ and $f_θ\sim9$~km s$^{-1}$, respectively. Velocities of Cepheids older than 120 Myr are currently giving a wavelength $λ_{R,θ}\sim5$~kpc. This value differs significantly from one that we obtained from the samples of young Cepheids. An analysis of positions and velocities of old Cepheids, calculated by integrating their orbits backward in time, made it possible to determine significantly more reliable values of the parameters of the spiral density wave: wavelength $λ_{R,θ}=2.7$~kpc, amplitudes of radial and tangential perturbations are $f_R=7.9$~km s$^{-1}$ and $f_θ=5$~km s$^{-1}$, respectively.

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。

↑