Australian Journal of Physics最新文献_第10页

Effect of radial wavevector on collisional drift waves in a toroidal heliac 径向波矢量对环形螺旋推进器中碰撞漂移波的影响

Australian Journal of Physics Pub Date : 1999-05-01 DOI: 10.1071/P98071

J. Lewandowski, Richard Ellem

引用次数: 2

Redshift and luminosity dependence of linear sizes of compact steep spectrum sources and the quasar/galaxy unification scheme 紧致陡谱源线性尺寸的红移和光度依赖性及类星体/星系统一方案

Australian Journal of Physics Pub Date : 1999-05-01 DOI: 10.1071/P97011

A. Ubachukwu, J. N. Ogwo

引用次数: 11

A millisecond x-ray reflectometer 毫秒x射线反射计

Australian Journal of Physics Pub Date : 1999-05-01 DOI: 10.1071/P98077

J. White, A. Brown, R. F. Garrett, D. King, T. Dowling

引用次数: 6

Dependence of Faraday effects on radio luminosity and redshift 法拉第效应对射电光度和红移的依赖性

Australian Journal of Physics Pub Date : 1999-05-01 DOI: 10.1071/P98004

A. Ubachukwu, A. C. Ugwoke, A. Chukwude

引用次数: 1

Radial structure of electron drift waves in tokamak geometry 托卡马克几何中电子漂移波的径向结构

Australian Journal of Physics Pub Date : 1999-05-01 DOI: 10.1071/P98067

J. Lewandowski

引用次数: 2

Vapour-liquid equilibrium properties for two- and three-dimensional Lennard-Jones fluids from equations of state 基于状态方程的二维和三维Lennard-Jones流体的气液平衡性质

Australian Journal of Physics Pub Date : 1999-05-01 DOI: 10.1071/P98051

Á. Mulero, F. Cuadros, C. Faúndez

引用次数: 11

Twinkle, twinkle little pulsar/quasar 闪烁，闪烁，小小的脉冲星/类星体

Australian Journal of Physics Pub Date : 1999-05-01 DOI: 10.1071/P98076

D. Melrose

{"title":"Twinkle, twinkle little pulsar/quasar","authors":"D. Melrose","doi":"10.1071/P98076","DOIUrl":"https://doi.org/10.1071/P98076","url":null,"abstract":"The twinkling of stars is a familiar example of scintillations, due to turbulence in the Earth’s atmosphere causing fluctuations in the refractive index of the air along the line of sight. Scintillations lead to time variations in the apparent position of the source, and hence to an angular broadening on integration over an observation time. Scintillations also lead to fluctuations in the intensity of the source. Pointlike astronomical radio sources such as pulsars and (the compact cores of some) quasars scintillate due to fluctuations in the electron density along the line of sight through the interstellar medium. For quasars, low-frequency (100s of MHz) variability over periods of years is a scintillation effect, as are probably more rapid (as short as an hour) intensity variations at higher radio frequencies. Unlike the twinkling of stars, which is due to weak scintillations, the scintillations of radio sources are usually strong. Important qualitative effects associated with strong scattering are multipath propagation and a clear separation into diffractive and refractive scintillations. Quasars exhibit only refractive scintillations. Pulsars are extremely small and bright, and they vary temporally on a very short time scale, making them almost ideal sources on which to test our ideas on scintillations. Pulsars exhibit a variety of scintillation phenomena, due to both refractive and diffractive effects, the latter seen most clearly in dynamic spectra. These data are used to model the distribution of electrons through the Galaxy, to determine the distribution of pulsar velocities, and potentially to resolve the source region in a pulsar magnetosphere. These scintillation phenomena and their interpretation in terms of the theory of strong scintillations are reviewed briefly. The generalisation of the theory to include the birefringence of the plasma (Faraday effect), and its possible implications on the interpretation of circular polarisation, are then outlined. An attempt to generalise the theory to describe scattering by a distribution of discrete scattering objects is also discussed briefly.","PeriodicalId":170873,"journal":{"name":"Australian Journal of Physics","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132184621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Fibre optic shock velocity sensor for solids 固体纤维冲击速度传感器

Australian Journal of Physics Pub Date : 1999-05-01 DOI: 10.1071/P98068

J. Szajman, F. D. Marzio, M. Podlesak

引用次数: 58

Nonlinear dynamics of the dust grain charge and dust acoustic waves in a plasma with an ion beam 离子束等离子体中尘埃颗粒电荷和尘埃声波的非线性动力学

Australian Journal of Physics Pub Date : 1999-05-01 DOI: 10.1071/P98049

Y. Nejoh

引用次数: 18

Curvature pressure in a cosmology with a tired-light redshift 具有红光红移的宇宙学中的曲率压力

Australian Journal of Physics Pub Date : 1999-04-12 DOI: 10.1071/PH98065

D. F. Crawford

{"title":"Curvature pressure in a cosmology with a tired-light redshift","authors":"D. F. Crawford","doi":"10.1071/PH98065","DOIUrl":"https://doi.org/10.1071/PH98065","url":null,"abstract":"A hypothesis is presented that electromagnetic forces that prevent ions from following geodesics result in a curvature pressure that is very important in astrophysics. It may partly explain the solar neutrino deficiency and it may be the engine that drives astrophysical jets. However, the most important consequence is that, under general relativity without a cosmological constant, it leads to a static and stable cosmology. Combining an earlier hypothesis of a gravitational interaction of photons and particles with curved spacetime, a static cosmology is developed that predicts a Hubble constant of H = 60 . 2 km s− 1 Mpc− 1 and a microwave background radiation with a temperature of 3 . 0 K. The background X-ray radiation is explained, and observations of the quasar luminosity function and the angular distribution of radio sources have a better fit with this cosmology than they do with standard big-bang models. Although recent results (Pahre et al . 1996) for the Tolman surface brightness test favour the standard big-bang cosmology, they are not completely inconsistent with a static tired-light model. Most observations that imply the existence of dark matter measure redshift, interpret them as velocities, and invoke the virial theorem to predict masses that are much greater than those deduced from luminosities. If, however, most of these redshifts are due to the gravitational interaction in intervening clouds, no dark matter is required. Observations of quasar absorption lines, a microwave background temperature at a redshift of z = 1 . 9731, type 1a supernovae light curves and the Butcher–Oemler effect are discussed. The evidence is not strong enough to completely eliminate a non-evolving cosmology. The result is a static and stable cosmological model that agrees with most of the current observations.","PeriodicalId":170873,"journal":{"name":"Australian Journal of Physics","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123145684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7