论文标题
对HDCO和D $ _ {2} $ CO的调查，用于0/I Proto-Brown矮人
A survey of HDCO and D$_{2}$CO towards Class 0/I proto-brown dwarfs
论文作者
论文摘要
氘分离可以限制棕色矮人形成的早期阶段的物理和化学条件。我们在213-279 GHz的宽频率范围内提出了IRAM 3000万观察结果，甲醛（HDCO和D $ _ {2} $ CO）的单一和双重脱脂物种朝0/I级proto-Brown dwarfs（proto-bds）。检测到带有高能量级别$ \ leq $ 40 K的多个低激发HDCO和D $ _ {2} $ CO过渡线。 d $ _ {2} $ co/hdco，hdco/h $ _ {2} $ co，d $ _ {2} $ co/h $ _ {2} $ co的丰度比率在0.01至2.5之间，原始-BDS在低水素蛋白体中类似。 D $ _ {2} $ CO/HDCO $ \ sim $ 1.3-2.5的最高比率用于两个阶段0 Proto-BDS。这些物体可能具有温暖的Corino，类似于0类Protostars中报道的少数热Corino病例。平均d $ _ {2} $ co/hdco，d $ _ {2} $ co/h $ _ {2} $ co和hdco/h $ _ {2} $ co的比率相对较高，比当前的气格化学模型所预测的范围高，表明HDCO和D $ _ CO} $ co and grain and grain and grain and grain and contry and contry and contry and contry and contriende astive and contry and contriende astive。原始BD的内部在早期编队阶段。
Deuterium fractionation can constrain the physical and chemical conditions at the early stage of brown dwarf formation. We present IRAM 30m observations over a wide frequency range of 213-279 GHz of singly and doubly deuterated species of formaldehyde (HDCO and D$_{2}$CO) towards Class 0/I proto-brown dwarfs (proto-BDs). Multiple low-excitation HDCO and D$_{2}$CO transition lines with upper energy level $\leq$ 40 K are detected. The D$_{2}$CO/HDCO, HDCO/H$_{2}$CO, D$_{2}$CO/H$_{2}$CO abundance ratios range between 0.01 and 2.5 for the proto-BDs, similar to the range seen in low-mass protostars. The highest ratios of D$_{2}$CO/HDCO $\sim$1.3-2.5 are measured for two Stage 0 proto-BDs. These objects could possess a warm corino, similar to the few hot corino cases reported among Class 0 protostars. The mean D$_{2}$CO/HDCO, D$_{2}$CO/H$_{2}$CO, and HDCO/H$_{2}$CO ratios for the proto-BDs are comparatively higher than the range predicted by the current gas-grain chemical models, indicating that HDCO and D$_{2}$CO are formed via grain surface reactions in the dense and cold interiors of the proto-BDs at an early formation stage.
