Molecular clouds towards RCW 49 and Westerlund 2; Evidence for cluster formation triggered by cloud-cloud collision

We have made CO(J=2-1) observations towards the HII region RCW 49 and its ionizing source, the rich stellar cluster Westerlund 2 (hereafter Wd2), with the NANTEN2 sub-mm telescope. These observations have revealed that two molecular clouds in velocity ranges of -11 to +9 km/s and 11 to 21 km/s respectively, show remarkably good spatial correlations with the Spitzer IRAC mid-infrared image of RCW 49, as well a velocity structures indicative of localized expansion around the bright central regions and stellar cluster. This strongly argues that the two clouds are physically associated with RCW 49. We obtain a new kinematic distance estimate to RCW 49 and Wd2 of 5.4^{+ 1.1}_{- 1.4} kpc, based on the mean velocity and velocity spread of the associated gas. We argue that acceleration of the gas by stellar winds from Wd2 is insufficient to explain the entire observed velocity dispersion of the molecular gas, and suggest a scenario in which a collision between the two clouds ~4 Myrs ago may have triggered the formation of the stellar cluster.Comment: A version with higher resolution figures is available from http://www.a.phys.nagoya-u.ac.jp/~naoko/research/apjl2009/fur09_rev_highreso.pd

Identifying Context-Specific Categories for Visualizing Livability of Cities—a Case Study of Malmö

Livability is a concept being applied to cities, even though it is vague. Worldwide, there are several livable city ranking schemes in use, which compare the livability of cities by making use of standardized indicator sets. The research presented here recognizes, as a point of departure, that each city is unique, implying that comparisons of cities by standardized categories only does not adequately reflect the reality of each city. A qualitative approach to identify context-specific categories of livability is proposed and employed to the case of Malmo ̈ in Sweden. Through interviews, nine context-specific categories were identified and visualized. The findings of the study demonstrate that a qualitative approach enables a more in-depth description of livability categories because it can capture and illustrate relationships among the categories. An explicit awareness of such relationships may provide a more holistic perspective to city officials and planners as they aim to improve the livability of their cities. The study concludes that a qualitative approach in identifying context-specific categories can complement existing assessment schemes and allow a better grasp of livability challenges to cities

Identifying Context-Specific Categories for Visualizing Livability of Cities—a Case Study of Malmö

Livability is a concept being applied to cities, even though it is vague. Worldwide, there are several livable city ranking schemes in use, which compare the livability of cities by making use of standardized indicator sets. The research presented here recognizes, as a point of departure, that each city is unique, implying that comparisons of cities by standardized categories only does not adequately reflect the reality of each city. A qualitative approach to identify context-specific categories of livability is proposed and employed to the case of Malmo ̈ in Sweden. Through interviews, nine context-specific categories were identified and visualized. The findings of the study demonstrate that a qualitative approach enables a more in-depth description of livability categories because it can capture and illustrate relationships among the categories. An explicit awareness of such relationships may provide a more holistic perspective to city officials and planners as they aim to improve the livability of their cities. The study concludes that a qualitative approach in identifying context-specific categories can complement existing assessment schemes and allow a better grasp of livability challenges to cities

A peculiar jet and arc of molecular gas toward the rich and young stellar cluster Westerlund 2 and a TeV gamma ray source

We have discovered remarkable jet- and arc-like molecular features toward the rich and young stellar cluster Westerlund2. The jet has a length of ~100 pc and a width of ~10 pc, while the arc shows a crescent shape with a radius of ~30 pc. These molecular features each have masses of ~10000 solar mass and show spatial correlations with the surrounding lower density HI gas. The jet also shows an intriguing positional alignment with the core of the TeV gamma ray source HESS J1023-575 and with the MeV/GeV gamma-ray source recently reported by the Fermi collaboration. We argue that the jet and arc are caused by an energetic event in Westerlund 2, presumably due to an anisotropic supernova explosion of one of the most massive member stars. While the origin of the TeV and GeV gamma-ray sources is uncertain, one may speculate that they are related to the same event via relativistic particle acceleration by strong shock waves produced at the explosion or by remnant objects such as a pulsar wind nebula or microquasar

Identifying Context-Specific Categories for Visualizing Livability of Cities : a Case Study of Malmö

Livability is a concept being applied to cities, even though it is vague. Worldwide, there are several livable city ranking schemes in use, which compare the livability of cities by making use of standardized indicator sets. The research presented here recognizes, as a point of departure, that each city is unique, implying that comparisons of cities by standardized categories only does not adequately reflect the reality of each city. A qualitative approach to identify context-specific categories of livability is proposed and employed to the case of Malmo ̈ in Sweden. Through interviews, nine context-specific categories were identified and visualized. The findings of the study demonstrate that a qualitative approach enables a more in-depth description of livability categories because it can capture and illustrate relationships among the categories. An explicit awareness of such relationships may provide a more holistic perspective to city officials and planners as they aim to improve the livability of their cities. The study concludes that a qualitative approach in identifying context-specific categories can complement existing assessment schemes and allow a better grasp of livability challenges to cities

Comparative Analysis of Tsunami Recovery Strategies in Small Communities in Japan and Chile

The Sendai Framework for Disaster Risk Reduction emphasizes the need to rebuild better after a disaster to ensure that the at-risk communities can withstand a similar or stronger shock in the future. In the present work, the authors analyzed the reconstruction paths through a comparative analysis of the perspective of a community in Japan and another in Chile, and their respective local governments. While both countries are at risk to tsunamis, they follow different reconstruction philosophies. Data was gathered through key informant interviews of community members and local government officials, by adapting and modifying the Building Resilience to Adapt to Climate Extremes and Disasters (BRACED) 3As framework to a tsunami scenario. The 3As represent anticipatory, adaptive, and absorptive capacities as well as transformative capacities and respondents were asked to rate this according to their perspectives. It was found that while both communities perceive that much is to be done in recovery, Kirikiri has a more holistic and similar perspective of the recovery with their government officials as compared to Dichato. This shows that community reconstruction and recovery from a disaster requires a holistic participation and understanding