标题： 附近漩涡星系棒中的分子气体和恒星形成 显示英文标题

标题： Molecular Gas and Star Formation in Bars of Nearby Spiral Galaxies

摘要： 我们比较了来自邻近星系BIMA巡天（SONG）的六条螺旋星系（NGC 2903、NGC 3627、NGC 4321、NGC 5457、NGC 6946和IC 342）棒区内的分子气体分布与恒星形成活动。使用CO（J=1--0）发射线追踪的分子气体，在棒尘埃带的恒星棒前缘最为明亮。利用Hα发射线追踪的恒星形成活动则偏移到CO发射的前缘一侧。交叉相关分析显示：a）HII区域在CO发射的前缘一侧偏移0--800 pc；b）最大的偏移出现在最强的棒中；c）单个棒中的偏移范围很广，并且没有随着星系中心半径变化的系统性模式。CO-Hα偏移限制了恒星形成依赖于气体流动的方式。我们考察了可能的恒星形成情景，结合两种主要类型的棒气流模拟模型，即N体/粘性粒子模型和流体力学模型。尽管这两种模型的气流通常与观测到的偏移一致，但我们建议加入两相或多相介质以改善模型与观测之间的吻合度。 显示英文摘要

摘要： We compare the distribution of molecular gas and star formation activity in the bar region of six spirals (NGC 2903, NGC 3627, NGC 4321, NGC 5457, NGC 6946, & IC 342) from the BIMA Survey of Nearby Galaxies (SONG). The molecular gas, traced using the CO (J=1--0) emission line, is brightest along the leading edge of the stellar bar in the bar dust lanes. The star formation activity, traced using the Halpha emission line, is offset towards the leading side of the CO emission. A cross-correlation analysis shows that a) the HII regions are offset 0--800 pc on the leading side of the CO emission, b) the largest offsets are found in the strongest bars, and c) there is a wide range in offsets in a single bar with no systematic pattern as a function of the galacto-centric radius. The CO-Halpha offset constrains how stars may form depending on the gas flow. We examine possible star formation scenarios in context of the two main classes of bar gas flow simulations, the N-body/sticky particle and hydrodynamic models. Though both model gas flows are generally consistent with the observed offsets, we suggest the inclusion of a two- or multi-phase medium to improve the agreement between models and observation.