科研之友
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摘要
We have carried out an H(13)CO(+)(J = 1-0) core survey in a large area of 1 deg(2), covering most of the dense region in the Orion B molecular cloud, using the Nobeyama 45 m radio telescope with the 25-BEam Array Receiver System. We cataloged 151 dense cores using the clumpfind method. The cores have mean radius, velocity width, and mass of 0.10 +/- 0.02 pc, 0.53 +/- 0.15 km s(-1), and 8.1 +/- 6.4M(circle dot), respectively, which are very similar to those in the Orion A cloud. We examined the spatial relation between our H(13)CO(+) cores and the 850 mu m cores observed by Johnstone and colleagues in 2001 and 2006, and found that there are two types of spatial relationships: H(13)CO(+) cores with and without the 850 mu m cores. Since the mean density of the 850 mu m cores is higher than that of the H(13)CO(+) cores, we can interpret the H(13)CO(+) cores with 850 mu m cores as being more centrally concentrated and hence more evolved, compared with those without. Considering the relationship between the masses of the H(13)CO(+) and 850 mu m cores, we estimate the 850 mu m coremass CMF) using the H(13)CO(+) CMF through the generalization of the confusion model proposed by Ikeda and colleagues in 2007. Our predicted 850 mu m CMF is found to be quite consistent with that directly derived by Johnstone and colleagues. Furthermore, we predict the initial mass IMF) by the generalized confusion model assuming a star formation efficiency of 40% for the H(13)CO(+) cores, and found that our predicted IMF is consistent with the Galactic field-averaged IMF within uncertainties. This agreement may indicate that the origin of the IMF goes back to the cloud structures with densities of less than 10(4) cm(-3).
- 出版日期2009-2-1
- 单位中国科学院国家天文台
