牧夫座λ星的发现--南巡II
The Discovery of lambda Bootis Stars -- The Southern Survey II
摘要：
$λ$ Boo星是一种化学性质特殊的A型星，其丰度异常与贫金属物质的吸积有关。我们在对弱金属星和发射线星的有针对性的光谱调查中搜索了南半球的$λ$ Boo星。通过对308颗恒星的光谱分析和MK系统的分类，我们发现或共同发现了24颗新的$λ$ Boo星。我们还修订了11个已知的$λ$ Boo星的分类，其中一个原来是一个化学正常的快速旋转。我们发现，以前在文献中被归类为蓝色水平分支星或发射线A星的恒星有很高的概率是$λ$布星，虽然这一结论是基于小数统计。使用WISE红外通量，我们搜索我们的目标，红外过量，可能是由于原行星或碎片盘的吸积材料的来源。在我们的样本中的34颗$λ$ Boo星中，21颗在不同的主序星年龄上都有红外线过剩，这证实了并非所有的$λ$ Boo星都是年轻的。
英文摘要：
The $λ$ Boo stars are chemically peculiar A-type stars whose abundance anomalies are associated with the accretion of metal-poor material. We searched for $λ$ Boo stars in the southern hemisphere in a targeted spectroscopic survey of metal-weak and emission-line stars. Obtaining spectra for 308 stars and classifying them on the MK system, we found or co-discovered 24 new $λ$ Boo stars. We also revised the classifications of 11 known $λ$ Boo stars, one of which turned out to be a chemically normal rapid rotator. We show that stars previously classified in the literature as blue horizontal branch stars or emission-line A stars have a high probability of being $λ$ Boo stars, although this conclusion is based on small-number statistics. Using WISE infrared fluxes, we searched our targets for infrared excesses that might be attributable to protoplanetary or debris discs as the source of the accreted material. Of the 34 $λ$ Boo stars in our sample, 21 at various main-sequence ages have infrared excesses, confirming that not all $λ$ Boo stars are young.
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