Galactic outflows and the pollution of the galactic environment by supernovae

We here explore the effects of the SN explosions into the halo of star-forming galaxies like the Milky Way. Successive randomly distributed and clustered SNe explosions cause the formation of hot superbubbles that drive either fountains or galactic winds above the galactic disk, depending on the amount and concentration of energy that is injected by the SNe. In a galactic fountain, the ejected gas is re-captured by the gravitational potential and falls back onto the disk. From 3D non-equilibrium radiative cooling hydrodynamical simulations of these fountains, we find that they may reach altitudes up to about 5 kpc in the halo and thus allow for the formation of the so called intermediate-velocity-clouds (IVCs) which are often observed in the halos of disk galaxies. The high-velocity-clouds that are also observed but at higher altitudes (of up to 12 kpc) require another mechanism to explain their production. We argue that they could be formed either by the capture of gas from the intergalactic medium and/or by the action of magnetic fields that are carried to the halo with the gas in the fountains. Due to angular momentum losses to the halo, we find that the fountain material falls back to smaller radii and is not largely spread over the galactic disk. Instead, the SNe ejecta fall nearby the region where the fountain was produced, a result which is consistent with recent chemical models of the galaxy. The fall back material leads to the formation of new generations of molecular clouds and to supersonic turbulence feedback in the disk.     

李家云副总设计师

目前,直升机在民用领域的应用越来越广,作为中航工业直升机所副总设计师,请您谈谈在通用航空领域,中航直升机所将开发哪些新型民用直升机型号? 李家云:中国直升机行业在研制军用直升机满足国防建设的同时,也在积极开发民用直升机,直9、直11两型直升机先后取得中国民航型号合格证,由于方方面面的原因,占据国内民用直升机市场份额较小.     

徐朝梁 中国著名直升机总设计师

在此次珠海航展上,大型民用直升机AC313的精彩表演吸引了观众热切的目光,作为总设计师,您眼中的AC313是怎样的定位?徐朝梁:AC313是借鉴原有型号平台的成功设计经验、采用成熟的先进技术、按照国际最新的适航标准、采用与国际接轨的适航审定程序自主研发的全新民用直升机,是目前国内最大吨位的直升机。     

A morphological study of CMEs using wavelet analysis

The principal objective of this study is to analyze structures of Coronal Mass Ejections (CMEs) using a wavelet technique. We use data measured with the SOHO/LASCO coronographs C2–C3, EIT and STEREO COR1A–B, COR2A–B. We have found that different structures show up in a CME at different spatial scales of wavelets. We also study the orientation of the most intense flux and find the orientation of the structures in the CME.