A search for previously undetected optically thin disks around stars in the nearby, young, TW Hydrae Association (TWA) was conducted around 16 stars with sensitive 12 and 18 μm photometry. The survey could detect zodiacal-like dust, with temperature 200–300 K, at levels of LIR/L* = 7 × 10-3. Possible mid-infrared excess emission from TWA 17 was detected at the 2 σ level, but none of the other stars showed evidence for circumstellar dust. The rapid disappearance of large amounts of dust around the K- and M-type stars in this sample may mean that any planet formation in the terrestrial planet region was completed very quickly. There appears to be a bimodal distribution of dust disks in TWA, with stars having either copious or negligible warm dust.
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机译：在附近年轻的TW Hydrae协会（TWA）附近的恒星周围搜寻以前未检测到的光学薄盘，并用敏感的12和18μm光度法对16个恒星进行了搜索。该调查可以检测到温度为200–300 K的黄道状粉尘，其LIR / L * = 7×10-3。在2σ水平上检测到了TWA 17可能产生的中红外过量发射，但其他恒星均未显示出星尘的证据。在该样本中，K型和M型恒星周围大量尘埃的迅速消失可能意味着该地球行星区域中的任何行星形成都非常迅速地完成了。在TWA中，尘埃盘似乎是双峰分布的，恒星的尘埃含量足够大或可以忽略不计。
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