arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1902.04897astro-ph.SR
收藏

亨2-39行星状星云钡中心星的光谱分析

Spectral analysis of the barium central star of the planetary nebula Hen 2-39

L. Löbling, H. M. J. Boffin, D. Jones

备注：
26 pages, 18 figures
发表信息：
A&A 624, A1 (2019)
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

钡星是一种特殊的红巨星，其特征是s-过程元素的过剩以及碳的富集。这些恒星被发现与白矮星的同伴双星。这些恒星中较新形成的仍然被行星状星云包围着。精确的丰度测定的各种S-过程元素，特别是最轻的，短寿命的放射性核素锝将建立限制的S-过程元素的形成在渐近巨星分支恒星以及质量转移，通过，例如，恒星风，罗什瓣溢出，和共同的信封演变。我们对行星状星云Hen 2-39的K型次巨星中心恒星进行了详细的光谱分析，这是基于使用LTE模型大气的甚大望远镜紫外和视觉中阶梯摄谱仪获得的高分辨率光谱。我们确定了行星状星云Hen 2-39中心恒星的有效温度为$T_\mathrm{eff} = 4350 \pm 150$ K。它的光球碳丰度为$[\mathrm{C/H}]= 0.36 \pm 0.08$，钡丰度为$[\mathrm{Ba/Fe}]= 1.8 \pm 0.5$。我们发现大多数铁族元素（钙铁）的不足，并建立了锝（$\log ε_\mathrm{Tc} < 2.5$）的丰度上限。现有光谱的质量不足以精确测量所有s过程元素的丰度。尽管丰度和模型产量存在很大的不确定性，但得出的丰度与1.75-3.00 $M_\odot$范围内的祖先质量和$[\mathrm{Fe/H}]= -0.3 \pm 1.0$的金属丰度最一致。这一结果导致的结论是，这种系统的形成需要一个相对较大的质量传递，这是最容易通过风洛希瓣溢流获得。

英文摘要：

Barium stars are peculiar red giants characterized by an overabundance of s-process elements along with an enrichment in carbon. These stars are discovered in binaries with white dwarf companions. The more recently formed of these stars are still surrounded by a planetary nebula. Precise abundance determinations of the various s-process elements, especially, of the lightest, short-lived radionuclide technetium will establish constraints for the formation of s-process elements in asymptotic giant branch stars as well as mass transfer through, for example, stellar wind, Roche-lobe overflow, and common-envelope evolution. We performed a detailed spectral analysis of the K-type subgiant central star of the planetary nebula Hen 2-39 based on high-resolution optical spectra obtained with the Ultraviolet and Visual Echelle Spectrograph at the Very Large Telescope using LTE model atmospheres. We confirm the effective temperature of $T_\mathrm{eff} = 4350 \pm 150$ K for the central star of the planetary nebula Hen 2-39. It has a photospheric carbon enrichment of $[\mathrm{C/H}]= 0.36 \pm 0.08$ and a barium overabundance of $[\mathrm{Ba/Fe}]= 1.8 \pm 0.5$. We find a deficiency for most of the iron-group elements (calcium to iron) and establish an upper abundance limit for technetium ($\log ε_\mathrm{Tc} < 2.5$). The quality of the available optical spectra is not sufficient to measure abundances of all s-process elements accurately. Despite large uncertainties on the abundances as well as on the model yields, the derived abundances are most consistent with a progenitor mass in the range 1.75-3.00 $M_\odot$ and a metallicity of $[\mathrm{Fe/H}]= -0.3 \pm 1.0$. This result leads to the conclusion that the formation of such systems requires a relatively large mass transfer that is most easily obtained via wind-Roche lobe overflow.

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。

↑