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arXiv 2603.19367astro-ph.GA
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重新审视银河系恒星长棒和3 kpc臂

Revisiting the Milky Way stellar long bar and the 3 kpc arm

Instituto de Astrofísica de Canarias（加那利群岛天体物理研究所）；Universidad de La Laguna（拉古纳大学）；Inner Mongolia University（内蒙古大学）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；China West Normal University（西华师范大学）

M. Lopez-Corredoira, W. Wu, H. -F. Wang, F. Garzon

备注：
15 pages, 12 figures, accepted for publication in A&A. In memoriam of Terence J. Mahoney (1949-2025)
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AI总结：

研究通过分析M型巨星和Mira变星的距离分布，确认了银河系长棒的不对称性及3 kpc臂的形态特征，揭示了长棒与3 kpc臂的几何关系。

摘要：

背景。银河系中最为困难且未被探索的区域是位于银坐标$10^\circ \lesssim |\ell |\lesssim 30^\circ $，$|b|\lesssim 3^\circ $的高消光的平面中心区域，其中包含具有中间年龄恒星人口的长棒和3 kpc臂，其形态特性仍不明确。目标。我们旨在推进对这两个组件形态的认识。方法。我们检查了WISE-4.6μm中明亮的M型巨星的星数及其通过光谱视差法从APOGEE-DR17获得的距离分布，还检查了年轻OGLE-O-rich Mira变星的距离分布，并回顾了该区域红团距离确定的文献。结果。我们确认了平面区域内正负经度之间的不对称性，从而确认了长棒的必要性。我们获得长棒主轴与太阳-银河中心线之间的平均角度为$α=27.4^\circ \pm 1.5^\circ $，与三轴晕bulge对齐，半长轴长度约为4 kpc。长棒的末端与椭圆3 kpc臂接触，主轴再次与晕和长棒的主轴对齐，其切线视线对应于$\ell =-22^\circ $和$\ell=+27^\circ $。在天空中50度的范围内，这两个经度之间接近3 kpc臂的恒星在太阳系距离约5 kpc处被清晰检测到，而远3 kpc臂的恒星在太阳系距离9-12 kpc处被初步检测到。

英文摘要：

CONTEXT. One of the most difficult and unexplored regions of the Milky Way is the highly extincted in-plane central region within the Galactic coordinates $10^\circ \lesssim |\ell |\lesssim 30^\circ $, $|b|\lesssim 3^\circ $, where we have the long-bar and 3 kpc arm with intermediate-age stellar population, whose morphological properties are still unclear. AIMS. We aim to advance our knowledge of the morphology of these two components. METHODS. We examined star counts of bright M giants in WISE-4.6$μ$m and its distribution of distances derived from spectroscopic parallaxes with APOGEE-DR17. We also examined the distribution of distances of young OGLE-O-rich Mira variable stars, and reviewed the literature on red clump distance determination within that area. RESULTS. We corroborate the asymmetry between positive and negative longitudes in in-plane regions, thus confirming the necessity to include a long bar. We obtain an average angle between the major axis of the long bar and the line Sun-Galactic centre of $α=27.4^\circ \pm 1.5^\circ $, aligned with the triaxial bulge and a semi-major-axis length $\approx 4$ kpc. The tips of the long bar are in contact with the elliptical 3 kpc arm, with the major axis again aligned with the bulge and the long bar's major axes, whose tangential lines of sight correspond to $\ell =-22^\circ $ and $\ell=+27^\circ $. In the range of 50 degrees in the sky between these two longitudes, the stellar near 3 kpc arm is clearly detected at heliocentric distances around 5 kpc, and the stellar far 3 kpc arm is tentatively detected at heliocentric distances of 9-12 kpc.

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