AI 中文总结
研究首次在早B型恒星HD 37356中发现λ Boo现象，通过光谱分析确定其难熔元素亏损，证实其形成源于星周盘难熔元素亏损气体吸积机制。
AI 中文摘要
化学特殊的λ Boo型A型恒星的特征是难熔元素亏损，挥发性元素丰度正常。它们的形成通道尚未完全明确，但可为恒星形成过程中的星-盘-行星相互作用、系统演化后期的恒星-行星相互作用或恒星与星际介质的相互作用提供研究线索。我们首次在大质量早B型恒星HD 37356（Ori OB1c的成员）中检测到λ Boo现象。我们采用混合非局部热动平衡（non-LTE）模型大气技术分析高质量光谱，通过神经网络模拟合成光谱并结合马尔可夫链蒙特卡罗（MCMC）算法确定大气参数与元素丰度，同时利用盖亚（Gaia）数据和恒星演化模型推导恒星基本参数。HD 37356与摩根-基南（Morgan-Keenan）标准星γ Peg极为相似，光谱特征除难熔元素线系统性较弱外其余均吻合；定量分析得出的恒星参数也相近。挥发性元素丰度与宇宙标准丰度一致，而难熔元素丰度亏损0.25至0.45 dex，其中铁丰度偏低解释了HD 37356与γ Peg不同的脉动行为。在λ Boo型恒星的不同形成通道中，仅恒星形成阶段从星周盘吸积难熔元素亏损气体的机制在该案例中可行，该机制要求HD 37356为真正的慢旋转体，以防止经向环流等内部混合过程抹去丰度模式。
英文摘要
Chemically peculiar A-type stars of the $λ$ Boo class are characterised by depletions of refractory elements and normal volatile species. Their formation channel(s) have not yet been fully established, but they provide insight into star-disc-planet interactions during star formation, star-planet interactions in later system evolution, or interactions between stars and the interstellar medium. We report the first detection of the $λ$ Boo phenomenon in a massive early B-type star, HD 37356, a member of Ori OB1c. We analysed a high-quality spectrum using a hybrid non-LTE model-atmosphere technique. We determined atmospheric parameters and elemental abundances using neural networks to emulate synthetic spectra, coupled with a Markov chain Monte Carlo algorithm. We also derived the fundamental parameters of the star using Gaia data and stellar evolution models. HD 37356 closely resembles the Morgan-Keenan standard $γ$ Peg, closely agreeing in spectral signatures except for the lines of refractory elements, which are systematically weaker. The quantitative analysis yields similar stellar parameters. The abundances of volatile elements are compatible with cosmic standard abundances, while refractory species are depleted by 0.25 to 0.45dex. In particular, the lower iron abundance explains the different pulsational behaviour of HD 37356 compared to $γ$ Peg. Of the different formation channels for $λ$ Boo stars, only the accretion of gas depleted in refractory elements from the circumstellar disc during star formation appears to be feasible in this case. This scenario requires HD 37356 to be a true slow rotator in order to prevent the abundance pattern from being erased by internal mixing processes such as meridional circulation.
Comments6+3 pages, 6 figures, published in Astronomy & Astrophysics
Journal refA&A, 712, A68 (2026)
DOI：10.1051/0004-6361/202660977
