The Hobby-Eberly Telescope "Chemical Abundances of Stars in the Halo" (CASH) Project. I. The Lithium-, s-, and r-Enhanced Metal-Poor Giant HKII 17435-00532
Ian U. Roederer, Anna Frebel, Matthew D. Shetrone, Carlos Allende Prieto, Jaehyon Rhee, Roberto Gallino, Sara Bisterzo, Christopher Sneden, Timothy C. Beers, John J. Cowan
备注：
29 pages, 8 figures. Accepted for publication in ApJ. A full version of table 3 is available from the first author upon request
We present the first detailed abundance analysis of the metal-poor giant HKII 17435-00532. This star was observed as part of the University of Texas long-term project "Chemical Abundances of Stars in the Halo" (CASH). A spectrum was obtained with the High Resolution Spectrograph (HRS) on the Hobby-Eberly Telescope with a resolving power of R~15,000. Our analysis reveals that this star may be located on the red giant branch, red horizontal branch, or early asymptotic giant branch. We find that this metal-poor ([Fe/H]=-2.2) star has an unusually high lithium abundance (log eps (Li)=+2.1), mild carbon ([C/Fe]=+0.7) and sodium ([Na/Fe]=+0.6) enhancement, as well as enhancement of both s-process ([Ba/Fe]=+0.8) and r-process ([Eu/Fe]=+0.5) material. The high Li abundance can be explained by self-enrichment through extra mixing that connects the convective envelope with the outer regions of the H-burning shell. If so, HKII 17435-00532 is the most metal-poor star in which this short-lived phase of Li enrichment has been observed. The Na and n-capture enrichment can be explained by mass transfer from a companion that passed through the thermally-pulsing AGB phase of evolution with only a small initial enrichment of r-process material present in the birth cloud. Despite the current non-detection of radial velocity variations (over ~180 days), it is possible that HKII 17435-00532 is in a long-period or highly-inclined binary system, similar to other stars with similar n-capture enrichment patterns.
The Low Resolution Spectrograph of the Hobby-Eberly Telescope II. Observations of Quasar Candidates from the Sloan Digital Sky Survey
本文介绍了在霍比-埃伯利望远镜的低分辨率摄谱仪的调试阶段获得的类星体候选者的光谱。这些物体被确定为可能的类星体，来自斯隆数字巡天（Sloan Digital Sky Survey）的卫星图像数据。这10个源的r'星等通常在19-20之间，除了一个极红的天体，r'大约为23。曝光时间在10到25分钟之间获得的数据显示，四个候选者的光谱基本上没有特征，不是类星体，五个是红移在2.92到4.15之间的类星体（包括一个宽吸收线类星体），红色源是一个非常晚的M
