发表机构
National and Kapodistrian University of Athens; Università di Padova; INAF-Osservatorio Astronomico di Padova; University of Geneva; Koninklijke Sterrenwacht van België; SISSA; Purple Mountain Observatory, Chinese Academy of Sciences（雅典国立卡波迪斯特里安大学; 帕多瓦大学; 意大利国家天体物理研究所帕多瓦天文台; 日内瓦大学; 比利时皇家天文台; 的里雅斯特国际高等研究学院; 中国科学院紫金山天文台）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过相位分辨SED拟合，动态追踪SMC中13颗富碳米拉变星的物理参数，揭示温度、光学深度和光度的周期性变化，并恢复周光关系，强调时间分辨方法的重要性。
AI 中文摘要
富碳米拉变星是高度动态的恒星，其特征是大振幅径向脉动和强烈的质量损失。标准的光谱能量分布（SED）拟合通常依赖于时间平均的观测，这抹平了固有的变异性，只能得到近似的恒星和星周参数。为克服这些局限，我们动态追踪了小麦哲伦云（SMC）中13颗富碳米拉变星在整个脉动周期内的物理参数。结合来自$Gaia$、WISE、VMC、2MASS和OGLE的时间序列测光，我们重建了同时的多波段光变曲线。我们在14个不同相位提取独立的SED，并使用ATHENA-C网格对其进行建模。这种相位分辨的方法追踪了有效温度（$T_{\ m eff}$）、光学深度（$\ au_{0.55}$）和热光度（bolometric luminosity）的周期性变化。我们发现$T_{\ m eff}$的峰峰变化范围从约100 K到超过1000 K。$\ au_{0.55}$与热光度之间的强反相关表明，在最大亮度时尘埃凝结区被向外推，使得星周环境在光学上变得更薄。我们还恢复了经典的周光关系，并导出了径向膨胀速度和半径变化幅度，这些与独立测量结果一致。相位分辨拟合揭示了这些参数的真实动态范围，而静态拟合无法捕捉到这些。尽管受限于网格采样和缺乏收敛的静水力学模型的间隙，但显式地考虑时间依赖行为提供了恒星脉动与尘埃形成之间相互作用的更物理真实的图景。这强调了在研究大振幅变星时对时间分辨方法的迫切需求。
英文摘要
Carbon-rich Mira variables are highly dynamic stars characterized by large-amplitude radial pulsations and intense mass-loss. Standard spectral energy distribution (SED) fitting often relies on time-averaged observations, which flatten intrinsic variability and yield only approximate stellar and circumstellar parameters. To overcome these limitations, we dynamically trace the physical parameters of 13 carbon-rich Miras in the Small Magellanic Cloud (SMC) throughout their pulsation cycles. Combining time-series photometry from $Gaia$, WISE, VMC, 2MASS, and OGLE, we reconstruct simultaneous multi-band light curves. We extract independent SEDs at 14 distinct phases and model them using the ATHENA-C grid. This phase-resolved approach traces cyclic variations in effective temperature ($T_{\rm eff}$), optical depth ($τ_{0.55}$), and bolometric luminosity. We find peak-to-peak $T_{\rm eff}$ variations ranging from $\sim 100$ K to $>1000$ K. A strong anti-correlation between $τ_{0.55}$ and bolometric luminosity indicates the dust condensation zone is pushed outward at maximum brightness, rendering the circumstellar environment optically thinner. We also recover the classical Period-Luminosity relation and derive radial expansion velocities and radius variation amplitudes, which are consistent with independent measurements. Phase-resolved fitting reveals the true dynamic ranges of these parameters, which static fits fail to capture. Although limited by grid sampling and gaps where converged hydrostatic models are unavailable, explicitly accounting for time-dependent behavior provides a much more physically realistic picture of the interplay between stellar pulsation and dust formation. This highlights the critical need for time-resolved methodologies when studying large-amplitude variables.
CommentsManuscript accepted for publication in Astronomy and Astrophysics on 6 October 2026
