我們呈現27個位於獵戶座A區域在850μm波段明亮之分子雲核(Molcular Cores)的分子譜線觀測結果。所觀測的分子譜線皆利用野邊山天文台45米望遠鏡進行觀測，包含N2D+(J=1-0)、DNC(J=1-0)、DC3N(J=9-8)、HCO+(J=1-0)、H13CO+(J=1-0)、HN13C(J=1-0)和H13CN(J=1-0)。在所有觀測中皆可以偵測到HCO+與H13CO+，但卻沒偵測任何DC3N。我們觀測到10個分子雲核有N2D+，並在這些觀測目標中發現[N2D+]/[N2H+]豐度比隨著C18O耗盡因子(Depletion Factor)的下降而降低，代表當溫度上升時，CO會從灰塵中重新被釋放回環境中經由化學反應導致N2D+減少，此結果與理論相符合。同時我們也發現位於OMC1的8個分子雲核[HN13C]/[H13CN]比會在其他溫度低的分子雲核低，這符合[HNC]/[HCN]會隨著溫度上升時會降低的理論。H13CO+豐度被認為會在H2柱密度上升時會降低，而我們也有觀測到在獵戶座A區域也有相同的現象，這可能是因為H2柱密度高的區域會遮蔽住外來的宇宙射線使得游離度降低導致離子分子較難產生。為了調查我們所觀測的27個分子雲核是否有重力坍縮的情形，我們試著利用H13CO+與HCO+計算不對稱參數(Asymmetry Parameters)與金式質量(Jeans Mass)。但我們的結果顯示即使擁有24個分子雲核質量高於金式質量但卻只有8個分子雲核顯示藍不對稱性(Blue Asymmetry)，這樣的結果可能是因為我們觀測的分子雲核鑲嵌於絲狀結構的深處，而我們的不對稱參數是由低臨界密度(CriticalDensity)譜線計算而來，導致觀測的不對稱參數受到周圍絲狀結構的動力結構影響。

We present the results of molecular lines observations toward 27 cores in OrionA which are bright at 850μm continuum emission using Nobeyama Radio Observatory (NRO 45m). We observed N2D+(J=1-0),DNC(J=1-0),DC3N(J=9-8),HCO+(J=1-0),H13CO+(J=1-0),HN13C(J=1-0), andH13CN(J=1-0) lines .HCO+ and H13CO+ molecular lines were detected in all the cores. In contrast,DC3Ncan not be detected in all the cores. We detectedN2D+in 10 cores, and found their [N2D+]/[N2H+] abundance ratios are proportional to C18O depletion factor which is consistent with theory; when the temperature increase, CO wouldrelease from dust and destroy N2D+through the chemical reactions. We find that 8 sources in OMC1 have lower [HN13C] / [H13CN] ratio than those of other low temperature cores, which is consistent with the theory that [HNC]/[HCN] ra-tio will decrease with increasing temperature. H13CO+ abundance tends to decrease when H2 column density increase, which are observed in our sample. This is because high H2 column density will absorb cosmic ray that will decrease the ionization rate of molecules. We tried to use H13CO+(J=1-0) and HCO+(J=1-0)to calculate the asymmetry parameter and Jeans mass to investigate whether these 27 cores are under gravitational collapse. The result shows that only 8 cores dis-play blue asymmetry while all the 24 cores mass are larger than their Jeans mass.This result could be explain by the fact that these cores are deeply embedded by surrounding filament, and the asymmetry parameter is calculated from molecules with low critical density; therefore, the asymmetry parameter we calculated are affected by the dynamics of the surrounding filaments.

Baudry, A., Brouillet, N., & Despois, D. 2016, Comptes Rendus Physique, 17, 976 Beckwith, S. V. W., Sargent, A. I., Chini, R. S., & Guesten, R. 1990, Astron. J., 99, 924 Chira, R.-A., Smith, R. J., Klessen, R. S., Stutz, A. M., & Shetty, R. 2014, MNRAS,
444, 874

Crapsi, A., Devries, C. H., Huard, T. L., et al. 2005, Astron.& Astrophys., 439, 1023 Elmegreen, B. G. 1979, Astrophys. J., 232, 729
Emprechtinger, M., Caselli, P., Volgenau, N. H., Stutzki, J., & Wiedner, M. C. 2009, Astron.& Astrophys., 493, 89
Frerking, M. A., Langer, W. D., & Wilson, R. W. 1982, Astrophys. J., 262, 590

Graninger, D. M., Herbst, E., O¨ berg, K. I., & Vasyunin, A. I. 2014, Astrophys. J., 787, 74
Großschedl, J. E., Alves, J., Meingast, S., & Hasenberger, B. 2018, arXiv e-prints, arXiv:1812.08024
Jeans, J. H. 1902, Philosophical Transactions of the Royal Society of London Series A, 199, 1
Ko¨nyves, V., Andre´, P., Men’shchikov, A., et al. 2010, Astron.& Astrophys., 518, L106 Kounkel, M., Hartmann, L., Loinard, L., et al. 2017, Astrophys. J., 834, 142
Lane, J., Kirk, H., Johnstone, D., et al. 2016, The Astrophysical Journal, 833, 44 Lombardi, M., Bouy, H., Alves, J., & Lada, C. J. 2014, Astron.& Astrophys., 566, A45 Mangum, J. G., & Shirley, Y. L. 2016, Publ. Astron. Soc. Pacific, 128, 029201 Mardones, D., Myers, P. C., Tafalla, M., et al. 1997, 393, 113
Maruta, H., Nakamura, F., Nishi, R., Ikeda, N., & Kitamura, Y. 2010, Astrophys. J., 714, 680

Minamidani, T., Nishimura, A., Miyamoto, Y., et al. 2016, in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, Vol. 9914, , 99141Z
Muench, A., Getman, K., Hillenbrand, L., & Preibisch, T. 2008, Star Formation in the Orion Nebula I: Stellar Content, ed. B. Reipurth, Vol. 4, 483
Nakamura, F. 2019,Accepted, Publ. Astron. Soc. Japan

Nakamura, F., Oyamada, S., Okumura, S., et al. 2019, Publ. Astron. Soc. Japan, 32 Nutter, D., & Ward-Thompson, D. 2007, MNRAS, 374, 1413
Pagani, L., Roueff, E., & Lesaffre, P. 2011, Astrophys. J., 739, L35

Pagani, L., Vastel, C., Hugo, E., et al. 2009, Astron.& Astrophys., 494, 623 Salji, C. J., Richer, J. S., Buckle, J. V., et al. 2015, MNRAS, 449, 1769
Tang, X. D., Henkel, C., Menten, K. M., et al. 2018, Astron.& Astrophys., 609, A16