972 research outputs found

    Molecular environments of 51 Planck cold clumps in Orion complex

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    A mapping survey towards 51 Planck cold clumps projected on Orion complex was performed with J=1-0 lines of 12^{12}CO and 13^{13}CO at the 13.7 m telescope of Purple Mountain Observatory. The mean column densities of the Planck gas clumps range from 0.5 to 9.5×1021\times10^{21} cm2^{-2}, with an average value of (2.9±\pm1.9)×1021\times10^{21} cm2^{-2}. While the mean excitation temperatures of these clumps range from 7.4 to 21.1 K, with an average value of 12.1±\pm3.0 K. The averaged three-dimensional velocity dispersion σ3D\sigma_{3D} in these molecular clumps is 0.66±\pm0.24 km s1^{-1}. Most of the clumps have σNT\sigma_{NT} larger than or comparable with σTherm\sigma_{Therm}. The H2_{2} column density of the molecular clumps calculated from molecular lines correlates with the aperture flux at 857 GHz of the dust emission. Through analyzing the distributions of the physical parameters, we suggest turbulent flows can shape the clump structure and dominate their density distribution in large scale, but not affect in small scale due to the local fluctuations. Eighty two dense cores are identified in the molecular clumps. The dense cores have an averaged radius and LTE mass of 0.34±\pm0.14 pc and 3830+5_{-30}^{+5} M_{\sun}, respectively. And structures of low column density cores are more affected by turbulence, while those of high column density cores are more concerned by other factors, especially by gravity. The correlation of the velocity dispersion versus core size is very weak for the dense cores. The dense cores are found most likely gravitationally bounded rather than pressure confined. The relationship between MvirM_{vir} and MLTEM_{LTE} can be well fitted with a power law. The core mass function here is much more flatten than the stellar initial mass function. The lognormal behavior of the core mass distribution is most likely determined by the internal turbulence.Comment: Accepted to The Astrophysical Journal Supplement Series (ApJS

    Uniform Infall toward the Cometary H II Region in the G34.26+0.15 Complex?

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    Gas accretion is a key process in star formation. However, the gas infall detections in high-mass star forming regions with high-spatial resolution observations are rare. Here we report the detection of gas infall towards a cometary ultracompact H{\sc ii} region "C" in G34.26+0.15 complex. The hot core associated with "C" has a mass of \sim76 M_{\sun} and a volume density of 1.1×108\times10^{8} cm3^{-3}. The HCN (3--2), HCO+^{+} (1--0) lines observed by single-dishes and the CN (2--1) lines observed by the SMA show redshifted absorption features, indicating gas infall. We found a linear relationship between the line width and optical depth of the CN (2--1) lines. Those transitions with larger optical depth and line width have larger absorption area. However, the infall velocities measured from different lines seem to be constant, indicating the gas infall is uniform. We also investigated the evolution of gas infall in high-mass star forming regions. At stages prior to hot core phase, the typical infall velocity and mass infall rate are \sim 1 km s1^{-1} and 104\sim10^{-4} M_{\sun}\cdotyr1^{-1}, respectively. While in more evolved regions, the infall velocity and mass infall rates can reach as high as serval km s1^{-1} and 103102\sim10^{-3}-10^{-2} M_{\sun}\cdotyr1^{-1}, respectively. Accelerated infall has been detected towards some hypercompact H{\sc ii} and ultracompact H{\sc ii} regions. However, the acceleration phenomenon becomes inapparent in more evolved ultracompact H{\sc ii} regions (e.g. G34.26+0.15)

    Molecular gas and triggered star formation surrounding Wolf-Rayet stars

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    The environments surrounding nine Wolf-Rayet stars were studied in molecular emission. Expanding shells were detected surrounding these WR stars (see left panels of Figure 1). The average masses and radii of the molecular cores surrounding these WR stars anti-correlate with the WR stellar wind velocities (middle panels of Figure 1), indicating the WR stars has great impact on their environments. The number density of Young Stellar Objects (YSOs) is enhanced in the molecular shells at \sim5 arcmin from the central WR star (lower-right panel of Figure 1). Through detailed studies of the molecular shells and YSOs, we find strong evidences of triggered star formation in the fragmented molecular shells (\cite[Liu et al. 2010]{liu_etal12}Comment: 1 page, IAUS29

    Strategic alliances and firm value creation in China

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    Abstract: This study investigates the impact of 306 strategic alliances on the increment of firm value in the case of China. I apply the event study methodology using OLS market model to examine the abnormal returns of sample firms. The results show that the announcements of strategic alliance in China generate significant positive average abnormal return on the announcement date (0.96%) which reaches 1% significance level, suggesting a sizable increment in firm value by the formation of strategic alliance. The findings referring to alliance-specific characteristics are as follows: The abnormal return for firms entering policy alliance with local governments is significantly higher than the average level of abnormal return of total alliances (1.60% for policy alliances compared with 0.96% for the overall alliances on the announcement date). More specifically, the higher one government is indexed in Chinese administrative ranking, the higher abnormal return its partnering firm can achieve. As for financing alliance, the results provide evidence that the abnormal return of private firms (1.02%) is much greater than the abnormal return of state-owned enterprises (0.25%). Furthermore, there are no significant differences for abnormal returns between domestic alliances and international alliances. On considering the impact of firm-specific characteristics, the results indicate that the firm value increment by strategic alliance announcements has an inverse relationship with firm size but does not show any correlation with firm's growth opportunity. Contrast to the cases of firms in developed countries, the strategic alliances to low-tech companies contribute to increasing firm value more than the alliances to high-tech do (0.74% compared to 1.11% on the announcement date) in China. In addition, this study shows further evidence that for the firms involving alliances, the average abnormal return for private firms collaborating with state-owned partners reaches 1.15%, which is significantly positive at 1% level

    Secondary Metabolites from the Marine Sponge Genus Phyllospongia.

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    Phyllospongia, one of the most common marine sponges in tropical and subtropical oceans, has been shown to be a prolific producer of natural products with a broad spectrum of biological activities. This review for the first time provides a comprehensive overview of secondary metabolites produced by Phyllospongia spp. over the 37 years from 1980 to 2016

    The Mukokuseki Strategy and the Application of Pivot Translation in the Localization of Japanese Games

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    This article investigates the impact of using pivot language on the quality of game localization via a case study on the Japanese game Dark Souls 3. It first discusses the indirectness of the source text and the complexity of the target text in game localization by highlighting the “born translated” nature of the game narrative design. It then explicates the intricacy of having game audio voiced over in English only and including both direct and indirect translations in the localization workflow. It demonstrates the complication in evaluating localization quality from players’ perspectives and suggests that using English as a pivot language has certain advantages in ensuring multimodal cohesiveness in game localization. The rationale behind the localization approach is then explored through the lens of the mukokuseki strategy, which suggests that the application of pivot translation is driven by market globalization and, ultimately, the pursuit of economic gain