獵戶座 KL 熱分子雲核中蟻酸分子之順反異構物研究 A Study of the Conformers of Formic Acid in the Orion KL Hot Molecular Core

dc.contributor 管一政 zh_TW
dc.contributor Kuan, Yi-Jehng en_US
dc.contributor.author 游雅雯 zh_TW
dc.contributor.author Yo, Ya-Wen en_US
dc.date.accessioned 2020-10-19T06:52:24Z
dc.date.available 不公開
dc.date.available 2020-10-19T06:52:24Z
dc.date.issued 2020
dc.description.abstract 蟻酸,最簡單的有機酸,具有兩種構形異構物:反式和 順式-HCOOH。星際反式構形異構之 HCOOH 是太空中構形 異構-I 的氨基乙酸之可能前體分子,順式 HCOOH 則是構形 異構-II 的氨基乙酸之可能先驅物。反式 HCOOH 在獵戶座 KL 熱分子核心中檢測到,但至今尚未測到順式 HCOOH。 獵戶座 KL 是個含有許不同有機分子及豐富的化學之高質量 恆星形成區,而氨基乙酸則是最簡單的氨基酸。因此,我們 使用阿塔卡瑪大型毫米及次毫米波陣列(ALMA)進行觀測 獵戶座 KL,以搜索順式 HCOOH。 透過角秒分辨率和高靈敏度的 ALMA 觀測,我們分別在 ALMA 第 6 頻段的 255 GHz 和 ALMA 第 7 頻段的 324 GHz 獲得了至今最佳的獵戶座 KL 連續譜影像。此外我們成功地在獵戶座 KL 的五個區域中明確地偵測出六個順式 HCOOH 的分子躍遷譜線。經由旋轉躍遷圖的分析,我們也得出了順式和反式-HCOOH 的旋轉激發溫度和柱密度,也獲得了在 Compact Ridge 中順式對反式-HCOOH 的相對豐度比值,而所獲豐度比支持塵粒化學對順式-HCOOH 形成路徑在冰粒表面上的預測,而非紫外光轉換。我們在獵戶座 KL 中偵測到 順式 HCOOH 不僅有助於擴展我們對星際立體異構研究的理 解,而且對天文生物學研究也至關重要。 zh_TW
dc.description.abstract Formic acid, the simplest organic acid, has two conformational isomers: trans- and cis-HCOOH. Interstellar trans-conformer of HCOOH is the likely precursor of conformer I glycine in space, and the cis-HCOOH, of conformer II glycine. trans-HCOOH was detected in the Orion KL hot molecular core whereas cis-HCOOH has not been detected. Orion KL is a massive star-forming region containing numerous organic molecular species with rich chemistry, and glycine is the simplest amino acid. Hence, we observed Orion KL using the Atacama Large Millimeter/submillimeter Array (ALMA) to search for cis-HCOOH. With arcsecond-resolution and high-sensitivity of ALMA observations, we obtain the best continuum images of Orion KL to date in ALMA Bands 6& 7 at 255 GHz and 324 GHz, respectively. In addition, we successfully detected six transitions of cis- HCOOH unambiguously in five regions toward Orion KL. From rotation-diagram analysis, excitation temperatures and column densities of cis- and trans-HCOOH are derived. The abundance ratio of cis- to trans-HCOOH in the Compact Ridge is attained which supports the grain-chemistry prediction of the formation route of cis-HCOOH on icy-grain surface instead of photoswitching. Our detection of cis-HCOOH in Orion KL not only extends our comprehension of interstellar stereoisomerism but is also vital for astrobiology study. en_US
dc.description.sponsorship 地球科學系 zh_TW
dc.identifier G060244028S
dc.identifier.uri http://etds.lib.ntnu.edu.tw/cgi-bin/gs32/gsweb.cgi?o=dstdcdr&s=id=%22G060244028S%22.&%22.id.&
dc.identifier.uri http://rportal.lib.ntnu.edu.tw:80/handle/20.500.12235/111194
dc.language 英文
dc.subject 星際介質 zh_TW
dc.subject 熱分子雲核 zh_TW
dc.subject 獵戶座KL zh_TW
dc.subject 天文化學 zh_TW
dc.subject 星際立體異構學 zh_TW
dc.subject interstellar medium en_US
dc.subject hot molecular core en_US
dc.subject Orion KL en_US
dc.subject astrochemistry en_US
dc.subject interstellar stereoisomerism en_US
dc.title 獵戶座 KL 熱分子雲核中蟻酸分子之順反異構物研究 zh_TW
dc.title A Study of the Conformers of Formic Acid in the Orion KL Hot Molecular Core en_US
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