IDENTIFICATION OF H2CCC AS A DIFFUSE INTERSTELLAR BAND CARRIER
IDENTIFICATION OF H2CCC AS A DIFFUSE INTERSTELLAR BAND CARRIER
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H2CCC 作为漫射星际频带载波的识别
DOI：
10.1088/0004-637x/726/1/41
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
Á. Nagy
中科院分区：
文献类型：
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作者：
John P. Maier;G. Walker;D. Bohlender;D. Bohlender;Fabio J. Mazzotti;R. Raghunandan;J. Fulara;I. Garkusha;Á. Nagy
我们提供了强有力的证据，证明在4881和5450时的宽广弥散星际带(DIB)是由H_2CCC(L-C_3H_2)的B1B1←X1A1跃迁引起的。能带宽度较大是由于B1B1电子态寿命短所致。这些谱带是从霓虹灯矩阵中的吸收测量中预测出来的，并通过气相中的空腔衰荡观测到，并显示出与两个宽双星的轮廓和波长精确匹配的结果。 äDib的强度导致L-C3H2柱密度为∼5×1014厘米−2朝向HD 183143和∼2×1014厘米−2朝向HD 206267。尽管E(B − V)的值相似，但HD 204827中的4881和5450 ädib的强度不到HD 183143的三分之一，而星际C3的列密度在HD 204827中异常高，但在HD 183143中无法检测到。这可以理解，如果C3已经被氢化成L-C3H2等物种，则可以理解为HD 183143。在6150-6330 ä区还有三组旋转分辨的L-C3H2三联体。基于导出的光谱常数并与预期的仪器和星际谱线展宽进行卷积的模拟显示，这两组可观测到的三重态具有明显而微弱的DIBS可信的重合。第三组的区域太过被碲O2的α波段遮挡住了。
We present strong evidence that the broad, diffuse interstellar bands (DIBs) at 4881 and 5450 Å are caused by the B1B1 ← X1A1 transition of H2CCC (l-C3H2). The large widths of the bands are due to the short lifetime of the B1B1 electronic state. The bands are predicted from absorption measurements in a neon matrix and observed by cavity ring-down in the gas phase and show exact matches to the profiles and wavelengths of the two broad DIBs. The strength of the 5450 Å DIB leads to a l-C3H2 column density of ∼5 × 1014 cm−2 toward HD 183143 and ∼2 × 1014 cm−2 to HD 206267. Despite similar values of E(B − V), the 4881 and 5450 Å DIBs in HD 204827 are less than one-third their strength in HD 183143, while the column density of interstellar C3 is unusually high for HD 204827 but undetectable for HD 183143. This can be understood if C3 has been depleted by hydrogenation to species such as l-C3H2 toward HD 183143. There are also three rotationally resolved sets of triplets of l-C3H2 in the 6150–6330 Å region. Simulations, based on the derived spectroscopic constants and convolved with the expected instrumental and interstellar line broadening, show credible coincidences with sharp, weak DIBs for the two observable sets of triplets. The region of the third set is too obscured by the α-band of telluric O2.