Sequences in the Hardness Ratio-Peak Energy Plane of Gamma-Ray Bursts

The narrowness of the distribution of the peak energy of the vFv spectrum of gamma-ray bursts (GRBs) and the unification of GRB populations are great puzzles yet to be solved. We investigate the two puzzles based on the global spectral behaviors of different GRB populations, the long GRBs, the short GRBs, and the X-ray flashes (XRFs), in the HR - Ep plane (HR the spectral hardness ratio) with BATSE and HETE-2 observations. It is found that the long GRBs and the XRFs observed by HETE-2 seem to follow the same sequence in the HR-Ep plane, with the XRFs at the low end of this sequence. We fit the sequence by a universal Band function, and find that this sequence is mainly defined by the low energy index α, and is insensitive to the high energy index,β. With fixed β=-5, a best fit is given by α=-1.00 with X^2min/dof=2.2. The long and short GRBs observed by BATSE follow significantly different sequences in the HR-Ep plane, with most of the short GRBs having a larger hardness ratio than the long GRBs at a given Ep. For the long GRBs a best-fit yields α=-0.30 and β=-2.05. For the short GRBs, a best fit gives α=-0.60 with x^2min=1.1 (withβfixed at-2.0 because it is numerically unstable). The α value for the short GRBs is significantly greater than that for the long GRBs. These results indicate that the global spectral behaviors of the long GRB sample and the XRF sample are similar, while that of the short GRBs is different. The short GRBs seem to be a unique subclass of GRBs, and they are not the higher energy extension of the long GRBs.     

On the Period Variation of the W UMa-type Contact Binary V502 Ophiuchi

The variation in the orbital period of the W UMa type contact binary V502 Oph is analyzed. The orbital period exhibits a wavelike variation with a periodicity of 23.0 years and an amplitude of △P = 1.24×10~(-6) days superimposed on secular decrease of dP/dt = 1.68×10-7 day per year. The long-term decrease may be accompanied by the contraction of the secondary at a rate of 83 m per year and a mass transfer rate from the primary to the secondary of 4.28×10~8 M per year. The short-term oscillation may be explained by the presence of a third component. Orbital elements of the third body and its possible mass are presented.     

会议消息

随着社会发展和人类进步,地球环境问题,尤其是近现代环境变化问题日益引起人们的关注。保护环境,走可持续发展的道路已成为世界各国的共识和我国的一项基本国策。最近几年我国在现代环境污染防治、区域和全球环境变化等方面开展了深入系统的研究,取得了一批重要成果。为了推动环境科学、第四纪地质学和同位素地球化学研究的相互渗透,促进学科交叉和方法借鉴,给相关领域的专家们提供一个互相交流的机会,中国第四纪研究委员会高分辨率气候记录专业委员会、中国地质学会岩溶地质专业委员会、中国地质学会同位素专业委员会和国际地圈-生物圈计划…     

给学生一个空间,让他们自己去学习

从事天文教学工作后,我开始思考如何协调小学教着的深度和宇宙知识的复杂程度之间的关系。在不断地思考与实践中,我决定从教育目标、搭建平台和培养学生三个维度着手,一步步形成了目前中关村二小天文教学的初步格局。现仅此小文,跟大家探讨、交流。     

住建部、国土资源部:统筹地上地下空间开发,加快城市停车场规划建设

正日前,住房和城乡建设部、国土资源部联合印发《关于进一步完善城市停车场规划建设和用地政策的通知》,提出合理配置停车设施,提高空间利用效率,促进土地节约集约利用;充分挖潜利用地上地下空间,推进建设用地的多功能立体开发和复合利用;鼓励社会资本参与,加快城市停车场建设,逐步缓解停车难问题。     

小微企业用地难题怎解?

正小微企业在扩大就业、改善民生、促进稳定、增加税收、活跃经济等方面,具有十分重要的作用。在去年召开的东北三省经济工作座谈会上,李克强总理提出,要大力发展小微企业和民营经济。沈阳督察局调研发现,新常态下东北三省面临经济结构调整压力,企业融资难与用地难相互交织,小微企业用地困境如何破解?     

国务院决定在贫困地区试点水电矿产资源开发资产收益扶贫

正国务院办公厅日前印发《贫困地区水电矿产资源开发资产收益扶贫改革试点方案》。《方案》提出,从2016年底至2019年底,在集中连片特困地区县和国家扶贫开发工作重点县选择一批水电、矿产资源开发项目,开展资产收益扶贫改革试点。总体要求指导思想全面贯彻党的十八大和十八届三中、四中、五中全会精神,深入贯彻习近平总书记系列重要讲话精神,认真落实党中央、国务院决策     

蓝色引擎强劲发力——国家海洋局局长王宏专访

正近日,国家海洋局局长王宏接受记者专访。专访中,王宏局长着重介绍了我国"十二五"时期海洋经济发展的新亮点和"十三五"期间海洋经济的新举措。海洋经济有五大新亮点记者:"十二五"期间,我国海洋经济发展状况如何?王宏:"十二五"以来,面对错综复杂的国内外经济发展环境,我国海洋经济总体保持平稳运行,产业结构进入深度调整的新阶段,为东部沿海地区加快发展后劲奠定了基础。具体概括为"五个新":1.海洋经济发展步入"新常态"。当海洋经济进入"新常态"意味着海洋产业结构的深度调整和海洋经济发展方式的加快转变。2.海洋产业结构调整呈现"新亮点"。海洋经济发展正在从规模速