1.3毫米波段的多電波源光譜普查

Abstract

星際空間之氣相的分子轉動躍遷，其所放出的電磁輻射一般都落在毫米波或次毫米波波段。為了探測在星際中的各式分子，本次研究是使用前美國國家電波天文台(National Radio Astronomy Observatory)在基特峰(Kitt Peak)上的十二米電波望遠鏡，從1997年11月至2000年4月分多次觀測，對Orion KL、Sgr B2(N)與W51 e1/e2等三個熱分子雲核進行1.3毫米波段的光譜普查，並共觀測了45個不同的頻帶。我們使用UniPOPS分析軟體將這些頻帶作資料處理與校正後，並採用美國國家標準暨科技研究局的已觀測確認之星際分子微波躍遷資料庫、美國噴射推進實驗室加州理工學院的分子光譜資料庫與Cologne分子光譜資料庫等三個資料庫中分子光譜的資料進行譜線的比對與辨識。我們將這45個頻帶中的分子譜線比對後標示於光譜中，並對所觀測到的分子譜線之特性進行探討。在本次三個熱分子雲核的普查中，總計在Orion KL、Sgr B2(N)與W51 e1/e2中可辨識的分子譜線分別為413、302及262條，無法確認譜線分別為143、84和71條。在本次觀測中偵測到不少來自有機分子的譜線，其中有些更是前生物期重要之有機分子(如甘胺酸)，這對天文生物學(Astrobiology)的研究，有極深遠的含意。

The length of wave of radiations, which was released by the transition of gas-phase molecules in the interstellar space, generally fall within the length from millimeter waves to submillimeter waves. For the purpose of exploring kinds of molecules in the interstellar space, this study examined the data of three hot molecular cores, Orion KL, Sgr B2(N), and W51 e1/e2, which were observed by a 12-meter radio telescope in the National Radio Astronomy Observation in the Kitt Peak from November, 1997 to April, 2000. We conducted a spectral survey of 1.3-millimeter wave span of three hot-molecular cores, and observed 45 bandscans as well. We used the UniPOPS software to calibrate the raw data and obtain the frequency of spectral lines in these bandscans. Then the frequency would be compared with three databases, NIST、JPL and CDMS to identify their characteristics. We marked the identified spectral lines within the 45 bandscans, and brought up a further discussion to explore the characteristics of the molecular spectroscopy. In this survey of the hot molecular cores, we found that there were 413 identified and 143 unidentified molecular spectral lines in Orion KL, and 302 and 84 in Sgr B2(N), 262 and 71 in W51 e1/e2 respectively. In addition, spectral lines of many organic molecules, such as glycine, which was an important molecule in the prebiological period, were detected in this survey. It was a crucial finding in the astrobiological research.