arXiv 2302.100222023-02-20astro-ph.GAastro-ph.SR

利用盖亚BP/RP光谱的无监督分类在银河系棒球中寻找富C长周期变星

Hunting for C-rich long-period variable stars in the Milky Way's bar-bulge using unsupervised classification of Gaia BP/RP spectra

Jason L. Sanders, Noriyuki Matsunaga

备注：: 20 pages, 13 figures, accepted for publication in MNRAS
DOI：: 10.1093/mnras/stad574

阅读 PDF

arXiv 页面 ↗HTML 原文 ↗

摘要：

富氧和富碳AGB源的分离对于它们作为局部和宇宙学距离和年龄/金属丰度指标的准确使用至关重要。我们研究使用无监督学习算法对盖亚DR 3的BP/RP光谱中的长周期变量进行化学分类。即使在存在大量星际尘埃的情况下，光谱也会分成两组，分别来自富O和富C源。鉴于这些分类，我们利用一个监督的方法来分离O-丰富和C-丰富的来源，没有BP/RP光谱，而是宽带光学和红外测光发现我们的C-丰富的分类纯度约为$95$ %。我们测试和验证的分类对其他主张的颜色分色测光的基础上。此外，我们证明了BP/RP光谱的潜力，寻找S型星或那些可能的共生源与强发射线。虽然我们的分类表明，银河棒球是主机非常少的富C长周期变星，我们确实发现了一小部分的富C恒星的周期$>250\,\mathrm{day}$是空间和运动学上一致的酒吧球成员。我们认为，所观察到的数量，空间排列，运动学和周期分布的组合不赞成年轻的贫金属恒星形成的情况下，无论是在原地或吸积主机，相反，这些恒星很可能是二进制演化的结果和已经观察到的酒吧隆起的蓝色掉队星的演化版本。

英文摘要：

The separation of oxygen- and carbon-rich AGB sources is crucial for their accurate use as local and cosmological distance and age/metallicity indicators. We investigate the use of unsupervised learning algorithms for classifying the chemistry of long-period variables from Gaia DR3's BP/RP spectra. Even in the presence of significant interstellar dust, the spectra separate into two groups attributable to O-rich and C-rich sources. Given these classifications, we utilise a supervised approach to separate O-rich and C-rich sources without BP/RP spectra but instead given broadband optical and infrared photometry finding a purity of our C-rich classifications of around $95$ per cent. We test and validate the classifications against other advocated colour-colour separations based on photometry. Furthermore, we demonstrate the potential of BP/RP spectra for finding S-type stars or those possibly symbiotic sources with strong emission lines. Although our classification suggests the Galactic bar-bulge is host to very few C-rich long-period variable stars, we do find a small fraction of C-rich stars with periods $>250\,\mathrm{day}$ that are spatially and kinematically consistent with bar-bulge membership. We argue the combination of the observed number, the spatial alignment, the kinematics and the period distribution disfavour young metal-poor star formation scenarios either in situ or in an accreted host, and instead, these stars are highly likely to be the result of binary evolution and the evolved versions of blue straggler stars already observed in the bar-bulge.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

相关论文