论文标题
螺旋形臂和银河系的角度差距Cepheids
Spiral arms and the angular momentum gap in Milky Way Cepheids
论文作者
论文摘要
外银盘上经典头虫的角度分布是双模式的，差距为$ l_ \ mathrm {gap} = 2950 \，\ Mathrm {km} \，\ Mathrm {s} $ r = 13 \，\ mathrm {kpc} $，虽然在圆盘星的一般人群中没有发现类似的功能。我们表明，在相同方位角的多个螺旋臂段中的恒星形成会导致这种多模式迅速溶解，并且仅在年轻的恒星中显示。与其他解释不同，例如与银河棒的1：1轨道共振，这也解释了在$ l_ \ mathrm {gap} $上观察到的恒星翘曲的陡峭，因为相邻的螺旋臂代表了扭曲的气盘的不同部分。在这种情况下，正如观察到的那样，差距显然只存在于年轻恒星中，而最纯粹的恒星动力学起源会影响所有椎间盘种群，包括较旧的圆盘恒星。
The angular-momentum distribution of classical Cepheids in the outer Milky Way disc is bi-modal with a gap at $L_\mathrm{gap}=2950\,\mathrm{km}\,\mathrm{s}^{-1}\,\mathrm{kpc}$, corresponding to $R=13\,\mathrm{kpc}$, while no similar feature has been found in the general population of disc stars. We show that star formation in multiple spiral arm segments at the same azimuth leads to such multi-modality which quickly dissolves and only shows in young stars. Unlike other explanations, such as a 1:1 orbital resonance with the Galactic bar, this also accounts for the observed steepening of the stellar warp at $L_\mathrm{gap}$, since the adjacent spiral arms represent different parts of the warped gas disc. In this scenario the gap is clearly present only in young stars, as observed, while most purely stellar dynamical origins would affect all disc populations, including older disc stars.
