利用红外推导的AGB恒星距离绘制银河系内区结构图
Mapping the Inner Milky Way with Infrared-Derived Distances to AGB Stars
AI总结：
本研究开发XGBoost回归模型，利用AKARI红外测光估算3.6万余颗AGB恒星距离，拓展了银心尘埃遮蔽AGB群体的距离覆盖，揭示了银核与银盘米拉变星的空间分布特征。
AI中文摘要：
银河系（MW）的结构与演化可通过对银心区域演化恒星群体的距离估计来追踪。然而，由于仪器限制、大角直径及复杂变异性，多数这类天体的直接天体测量距离仍无法获取或高度不确定。本研究中，我们开发了一种监督机器学习模型，用于估算从AKARI中红外巡天选出的富氧渐近巨星支（AGB）恒星的统计距离。我们构建了XGBoost回归模型，利用一组基于SED推导距离的AGB恒星训练集，将多波段红外测光映射至距离，在独立测试集上实现了6%的平均绝对百分比误差（MAPE）。我们获取了超过36000个AGB天体的距离估计，总误差幅度为36%，极大拓展了银道面中尘埃遮蔽AGB群体的距离覆盖范围（0.5-20千秒差距）。我们发现其与已报道的银河系米拉变星距离及独立周光关系吻合良好。利用拓展的距离集，我们进一步研究了银核与银盘内米拉变星的空间分布：长周期米拉变星更倾向于追踪银核的棒状结构，而短周期米拉变星则分布于银盘；此外，银核与银盘的相对标度高度大致恒定但存在差异，银核的垂直弥散度约大30%。这些发现表明，红外测光推导的统计距离可重建大尺度银河系结构，并确立长周期米拉变星为银河系严重遮蔽区域恒星群体的有效示踪体。
英文摘要：
The structure and evolution of the Milky Way (MW) can be traced with distance estimates to the evolved stellar populations in the inner galactic region. However, direct astrometric distances remain unavailable or highly uncertain for the majority of these sources due to instrumental limitations, large angular diameters, and complex variability. In this work, we develop a supervised machine-learning model to estimate statistical distances to oxygen-rich asymptotic giant branch (AGB) stars selected from the AKARI mid-infrared survey. We build an XGBoost regression model that maps multi-band IR photometry to distance using a training set of AGB stars with previously derived SED-based distances achieving a mean absolute percentage error (MAPE) of 6% on an independent test set. Distance estimates for over 36,000 AGB sources are obtained within a 36% total error margin, greatly expanding distance coverage (0.5-20 kpc) for dust-obscured AGB populations in the Galactic plane. We find good agreement with reported distances for Galactic Mira variables and independent period-luminosity relations. Utilizing the expanded distance set, we further investigate the spatial distribution of Mira variables in the Galactic bulge and disk. Longer-period Miras preferentially trace the bulge's barred morphology compared to their shorter-period counterparts that populate the disk. We also find roughly constant, but differing, relative scale heights for the bulge and disk, with the bulge vertical dispersion about 30% larger. These findings show that IR photometry-derived statistical distances can recover large-scale Galactic structures and establish long-period Mira variables as efficient tracers of stellar populations in heavily obscured regions of the MW.
