• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The Astrophysical journal >DETECTION OF ACETAMIDE (CH_3CONH_2): THE LARGEST INTERSTELLAR MOLECULE WITH A PEPTIDE BOND
【24h】

DETECTION OF ACETAMIDE (CH_3CONH_2): THE LARGEST INTERSTELLAR MOLECULE WITH A PEPTIDE BOND

机译：乙酰胺（CH_3CONH_2）的检测：最大的星际分子，带有肽键

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Acetamide (CH_3CONH_2) has been detected in emission and absorption toward the star-forming region Sagittarius B2(N) with the 100 m Green Bank Telescope (GBT) by means of four A-species and four E-species rotational transitions. All transitions have energy levels less than 10 K. The Sgr B2(N) cloud is known to have a cold halo with clumps of gas at several different velocities. Absorption features are largely characterized by local standard of rest (LSR) velocities that are typical of the two star-forming cores with systemic LSR velocities of + 64 and + 82 km s~(-1). Continuum sources embedded within the star-forming cores give rise to the absorption from the molecular gas halo surrounding the cores. Emission features are seen at an approximate intermediate LSR velocity of +73 km s~(-1) that characterizes the widespread molecular halo that has a spatial scale of a few arcminutes. Two low-energy transitions of formamide (HCONH_2) were also observed with the GBT toward Sagittarius B2(N) since formamide is the potential parent molecule of acetamide; both molecules are the only interstellar species with an NH_2 group bound to a CO group, the so-called peptide bond, that provides the linkage for the polymerization of amino acids. While the acetamide transitions observed appear to be confined to the cold (～8 K) halo region, only the 1_(01)-0_(00) transition of formamide appears to be exclusively from the cold halo; the 3_(12)-3_(13) transition of formamide is apparently contaminated with emission from the two hot cores. The relative abundance ratio of acetamide to formamide is estimated to be in the range of ～0.1 to ～0.5 in the cold halo. The exothermic neutral-radical reaction of formamide with methylene (CH_2) may account for the synthesis of interstellar acetamide in the presence of shock phenomenon in this star-forming region.
机译：通过100 m的格林班克望远镜（GBT），通过四个A物种和四个E物种的旋转跃迁，已向形成恒星的射手座B2（N）发射和吸收了乙酰胺（CH_3CONH_2）。所有过渡的能级均小于10K。已知Sgr B2（N）云具有冷晕，并且在数种不同速度下均具有气体团块。吸收特征在很大程度上以局部静止标准（LSR）速度为特征，这是两个恒星形成核的典型特征，系统性LSR速度分别为+ 64和+ 82 km s〜（-1）。嵌入恒星形成的核内的连续谱源引起了核周围分子气体晕的吸收。在大约+73 km s〜（-1）的中间LSR速度处观察到了发射特征，这表征了具有数个弧分的空间尺度的广泛分子晕。由于甲酰胺是乙酰胺的潜在母体分子，GBT还向人马座B2（N）观察到两个低能的甲酰胺（HCONH_2）跃迁。这两个分子都是唯一的具有NH_2基团与CO基团相连的星际物种，所谓的肽键为氨基酸的聚合提供了联系。尽管观察到的乙酰胺转变似乎仅限于冷（〜8 K）的晕圈区域，但只有甲酰胺的1_（01）-0_（00）转变似乎仅来自冷晕;甲酰胺的3_（12）-3_（13）跃迁显然被两个热芯的发射污染。在冷晕中，乙酰胺与甲酰胺的相对丰度比估计在〜0.1至〜0.5的范围内。甲酰胺与亚甲基（CH_2）的放热中性自由基反应可能解释了在该恒星形成区域中存在电击现象时星际乙酰胺的合成。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号