Spectroscopic Discovery of Brown Dwarf-like Secondary Stars in the Cataclysmic Variables LL Andromedae and EF Eridani
Spectroscopic Discovery of Brown Dwarf-like Secondary Stars in the Cataclysmic Variables LL Andromedae and EF Eridani
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DOI：
10.1086/319499
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发表时间：
2001-01
期刊：
影响因子：
--
通讯作者：
S. Howell;D. Ciardi
中科院分区：
文献类型：
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作者：
S. Howell;D. Ciardi
本文介绍了仙女座LL和波江座EF的红外光谱观测结果。我们的K波段光谱揭示了次级星星中甲烷吸收的存在，表明有效温度为1300 K，类似于“T”型甲烷棕矮星。EF Eri中的第二颗星星被认为更温暖，有效温度约为1650 K，光谱分类与L4-5星星一致。这两个副星系的理论质量估计为0.04-0.055兆焦耳（40-55兆焦耳）。我们对LL和EF Eri的红外光谱观测首次直接证明了后周期最小激变变星中含有类褐矮星二级星的理论预言。
Infrared spectroscopic observations of LL Andromedae and EF Eridani are presented. Our K-band spectrum of LL And reveals the presence of methane absorption in the secondary star indicating an effective temperature ≲1300 K, similar to a "T"-type methane brown dwarf. The secondary star in EF Eri is seen to be warmer with an effective temperature of ~1650 K and a spectroscopic classification consistent with an L4-5 star. Both secondaries have theoretical mass estimates of 0.04-0.055 M☉ (40-55 MJup). Our IR spectroscopic observations of LL And and EF Eri provide the first direct proof of the theoretical prediction that post-period minimum cataclysmic variables contain brown dwarf-like secondary stars.