- A group of Japanese chemists launched a project to disseminate a series of “Introduction to Chemistry” by the Internet. As the representative of the group, the author wishes to introduce the purpose of this project, and the structure of the series, to the potential users of the textbooks. For this purpose, the author prepared two short articles, one is the Q&A on the project, and the other Preface to the series. We wish the series would be used by many young students and citizens who have some difficulty in purchasing textbooks though they are very much interested in chemistry
- Open cluster (Wikipedia)
An open cluster is a type of star cluster made of tens to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and many more are thought to exist. Each one is loosely bound by mutual gravitational attraction and becomes disrupted by close encounters with other clusters and clouds of gas as they orbit the Galactic Center. This can result in a loss of cluster members through internal close encounters and a dispersion into the main body of the galaxy. Open clusters generally survive for a few hundred million years, with the most massive ones surviving for a few billion years. In contrast, the more massive globular clusters of stars exert a stronger gravitational attraction on their members, and can survive for longer. Open clusters have been found only in spiral and irregular galaxies, in which active star formation is occurring.