论文标题
在原始源B335周围的几个AU量表上的化学分化和温度分布
Chemical Differentiation and Temperature Distribution on a Few au Scale around the Protostellar Source B335
论文作者
论文摘要
在原恒星附近解决物理和化学结构对于阐明其发展到行星系统至关重要。在这种情况下，我们以0的分辨率进行了1.2 mm的观测，以0的分辨率对低质量的原始源b335进行。通过使用主成分分析图像多维数据集的分子，含氧分子的分布比含氧的分子更紧凑CH3OH和CH2DOH的包络方向衍生为150-165K。另一方面，分布较小的HCOOH和NH2CHO的方向是75-112 K，并且明显低于CH3OH和CH2DOH的HH2CHO。这意味着由CH3OH和CH2DOH所追踪的外膜是通过其他机制而不是原恒星加热加热的。我们在这里提出吸积冲击作为加热机制。化学分化和几个AU量表上的温度结构为我们提供了关键信息，以进一步了解原始源中的化学过程。
Resolving physical and chemical structures in the vicinity of a protostar is of fundamental importance for elucidating their evolution to a planetary system. In this context, we have conducted 1.2 mm observations toward the low-mass protostellar source B335 at a resolution of 0."03 with ALMA. More than 20 molecular species including HCOOH, NH2 CHO, HNCO, CH3 OH, CH2 DOH, CHD2 OH, and CH3 OD are detected within a few 10 au around the continuum peak. We find a systematic chemical differentiation between oxygen-bearing and nitrogen-bearing organic molecules by using the principal component analysis for the image cube data. The distributions of the nitrogen-bearing molecules are more compact than those of the oxygen-bearing ones except for HCOOH. The temperature distribution of the disk/envelope system is revealed by a multi-line analysis for each of HCOOH, NH2 CHO, CH3 OH, and CH2 DOH. The rotation temperatures at the radius of 0."06 along the envelope direction of CH3OH and CH2DOH are derived to be 150-165 K. On the other hand, those of HCOOH and NH2CHO, which have a smaller distribution, are 75-112 K, and are significantly lower than those for CH3OH and CH2DOH. This means that the outer envelope traced by CH3OH and CH2DOH is heated by additional mechanisms rather than the protostellar heating. We here propose the accretion shock as the heating mechanism. The chemical differentiation and the temperature structure on a few au scale provide us with key information to further understand chemical processes in protostellar sources.
