Detection of water masers in a sample of 84 IRAS sources

Using a newly installed system on the 25 m telescope of Urumqi Observatory, we searched for H20 maser emission towards 84 IRAS sources including young stellar objects （YSOs） and candidates for OFUIR stars. Water masers were detected in four star formation regions and one envelope of late type of stars for the first time. New water maser components were measured in two sources. In a maser source with no water maser emission detected six years ago, strong maser emission was found at different velocities, showing that there was a new explosion of water maser in this source.     

Review of galactic and extragalactic searches for class I methanol masers

Class I methanol masers are important tools for investigations of star formation throughout the Universe. Recently, a series of surveys for class I methanol masers at the 95 GHz transition toward samples of young stellar objects have been undertaken. These surveys have resulted in the detection of about 200 new class I methanol masers and combined with previous increased the number of known observations they have class I methanol masers in our Galaxy to ~400. From analysis of the relationship between class I methanol maser emission and associated astrophysical objects, it has been shown that the intensity of the class I methanol maser emission is closely correlated with the properties of the 1.1 mm Bolocam Galactic Plane Survey （BGPS） dust continuum sources and outflow properties. This further supports the hypothesis that class I methanol masers are collisionally pumped and excited in shocked regions. Based on these observations, it can be inferred that the BGPS catalog is likely to provide more reliable samples for targeting further class I methanol maser searches. A new survey for class I methanol masers toward a larger size sample of BGPS sources to test this is currently underway. The prospects for detecting class I methanol megamasers in extragalactic sources is discussed, and observations constituting the first sensitive search have been proposed.     

激光:从发明到应用

本文通过对激光发明到应用过程中几个重要问题的历史考察 ,论述在激光这一具体技术领域的产生和发展过程中 ,科技、经济和军事的动力共同发挥着作用 ;阐明在这一过程中 ,科学与技术的关系不是简单的、线性的关系 ,而是存在着多种多样的相互作用 :不仅新技术的产生依赖于科学知识 ,而且 ,在新技术建立之后 ,技术的发展又为科学研究提供了强大的动力 ;说明新技术应用的不确定性不仅仅在于技术本身 ,而且在于社会如何运用已建立的技术能力。最后 ,本文指出 :(1)基础研究和应用是相互作用和相互缠绕的 ,因此应重视设计激励两者互动的政策 ;(2 )从科学发展角度看 ,新的科技突破可以带来无尽的发展机会 ,因此 ,应探索促进科技突破的激励机制 ;从经济和社会发展的角度 ,更重要的问题是如何开发和利用新的科技突破     

静电脉塞电子运动的稳定性

本文采用扰动方法分析了一种新的毫米波亚毫米波波源——静电电子回旋谐振脉塞(EECRM)系统中电子运动的稳定性问题。导出了系统中空间电荷场的分布,分析了电子稳态圆轨道在受到直流、交流空间电荷场影响时的稳定性,以及系统中存在的一类固有振荡特性和它的存在条件,求得了普遍条件下的色散方程并对其包含的不稳定点作了分析。     

单原子微波激射器中场的位相演化特征

利用Ｐｅｎｇ－Ｂａｒｎｅｔｔ位相理论和Ｊａｙｎｅｓ－Ｃｕｍｍｉｎｇｓ模型研究单原子微波激射器中场的位相演化特性，具体计算了初始光场是真空场时，场的位相几率分布函数与位相涨落。     

微波激射器的发明

1954年微波激射器问世,距今已经55年了,这是20世纪的重大发明之一.     

大银河 新面貌

2005年2月，科学家宣布说，他们于2003年7月至2004年7月间利用射电望远镜观测了银河系英仙座臂中一个大质量分子云核中的甲醇分子宇宙微波激射，从而测量出英仙座臂距地球的距离为6370光年，这是人类第一次如此精确地测量出了这个距离，而这次测量也为精确地测量整个银河系提供了有效的手段，所以是一次意义非凡的突破。