SPICY星表中的近红外周期性：真正的年轻恒星天体与污染源

中文摘要 AI 辅助

红外（IR）大天区巡天使得研究恒星形成的局域性成为可能，不仅能在已知恒星孕育区的中心，还能在整个银道面上搜索年轻恒星天体（YSOs）。然而，这些空间无偏搜索受到污染的影响，最显著的是具有长周期变性的尘埃渐近巨星分支（AGB）恒星。利用时间序列分析，并利用YSOs与长周期变星（LPVs）不同的变时标，我们评估了空间上最无偏的YSO星表之一（\textit{Spitzer}/IRAC候选YSO，SPICY）的污染水平。区分这两类天体使我们能更可靠地得出银河系中孤立YSOs的频率及其意义的结论。我们将SPICY和VIRAC2星表（VVV/VVVX巡天）进行交叉匹配，为共同源构建近红外光变曲线，并计算其周期和振幅。污染源被识别为具有周期$P\geq 80\\,$天且振幅$\Delta K_{\rm s}\geq0.35\\,\rm{mag}$的周期性通量变化的源。从$58\\,737$个共同源中，我们根据长周期变异性识别出$742$个SPICY天体为LPV污染源，并识别出$307$个高置信度周期性YSO候选体，它们表现出与冷斑点一致的短周期通量变化。近红外和中红外振幅仅在LPVs中相关，表明存在共同的脉动起源。此外，所识别群体的空间分布进一步支持了我们的分类，LPVs优先与银心凸起相关，而YSOs位于最低银纬处。

英文摘要

Infrared (IR) large-sky surveys allow study of how localized star formation is, enabling searches for young stellar objects (YSOs) not only at the centers of known stellar nurseries but also across the Galactic plane. However, these spatially unbiased searches suffer from contamination, most notably from dusty asymptotic giant branch (AGB) stars characterized by long-period variability. Using time-series analysis, and taking advantage of the different variability timescales of YSOs against long-period variables (LPVs), we assess the level of contamination of one of the most spatially unbiased YSO catalogs (\textit{Spitzer}/IRAC Candidate YSO, SPICY). Distinguishing between these two groups lets us draw more robust conclusions about the frequency of isolated YSOs in our Galaxy and their implications. We cross-match the SPICY and VIRAC2 catalogs (VVV/VVVX Survey), build near-IR light curves for common sources, and compute their periods and amplitudes. Contaminants are identified as sources with periodic flux variations with periods $P\geq 80\,d$ and amplitudes $ΔK_{\rm s}\geq0.35\,\rm{mag}$. From $58\,737$ common sources, we identify $742$ SPICY objects as LPV contaminants based on their long-period variability, and identify $307$ high-confidence periodic YSO candidates exhibiting short-period flux changes consistent with cool spots. Near- and mid-IR amplitudes are correlated only among LPVs, suggesting a common pulsation origin. In addition, the spatial distribution of the identified populations further supports our classification, with LPVs preferentially associated with the bulge and YSOs at the lowest galactic latitudes.

发表机构

• Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学）
• Universidad de Concepción（康塞普西翁大学）
• European Southern Observatory（欧洲南方天文台）
• Millennium Nucleus on Young Exoplanets and their Moons (YEMS)（年轻系外行星及其卫星千年核中心 (YEMS)）
• Universidad de Santiago de Chile（智利圣地亚哥大学）
• Center for Interdisciplinary Research in Astrophysics and Space Exploration (CIRAS)（天体物理学与太空探索跨学科研究中心 (CIRAS)）

机构由 AI 辅助整理，请以论文原文为准。

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Accepted for publication in A&A