Observing the Sun at 20–650 MHz at Thermopylae with Artemis

Fine structure of type IV radio solar bursts with a great variety and complexity often give much information in different ways and enable estimation of various coronal characteristics. In this work, we expose our new method for fine structure revealing and separation of two basic kinds of type IV fine structure, as fibers and pulsations. We also estimate frequency drift of fibers from dynamic spectra, clean from continuous background, with a prototype method using 2-D Fourier transform and we estimate periodicities of fibers as well as pulsations with continuous wavelet transform. Working with the last method we found periodicities close to 3 min umbral oscillations and 5 min global solar oscillations.     

米波Ⅲ型爆发与日冕物质抛射

对澳大利亚Culgoora天文台射电频谱仪在太阳活动第23周峰年期间记录到的米波Ⅲ型爆发(20～420 MHz),与日冕物质抛射(CME)、Hα耀斑及相关事件进行了统计分析,发现米波Ⅲ型爆发与CME的关系没有Ⅱ、Ⅳ型爆发与CME的关系密切;米波Ⅲ型爆发发生的时间在CME之前25～30 min最多;72%的CME事件伴随长寿命的Hα耀斑.从这些观测特征出发,对米波Ⅲ型爆发、CME和Hα耀斑进行了定性的解释.     

Remnants of compact binary mergers

We investigate the long-term evolution and observability of remnants originating from the merger of compact binary systems and discuss the differences to supernova remnants. Compact binary mergers expel much smaller amounts of mass at much higher velocities, as compared to supernovae, which will affect the dynamical evolution of their remnants. The ejecta of mergers consist of very neutron rich nuclei. Some of these neutron rich nuclei will produce observational signatures in form of gamma ray lines during their decay. The composition of the ejecta might even give interesting constraints about the internal structure of the neutron star. We further discuss the possibility that merger remnants appear as recently discovered ‘dark accelerators’ which are extended TeV sources which lack emission in other bands.     

Length scales for September 14, 2005 solar noise storm

Source length scales are estimated for the September 14, 2005 solar noise storm from the spectral and temporal observed characteristics of the background continuum fluctuations and clusters of Type I bursts. The characteristic height of the magnetic structure where the noise storm source is located and the size of the source where Type I bursts clustering takes place were calculated. A lower limit for the height of the magnetic structure supporting the noise storm at 237 MHz was estimated too.     

GRB 980425, SN1998BW and the EMBH model

The EMBH model, previously developed using GRB 991216 as a prototype, is here applied to GRB 980425. We fit the luminosity observed in the 40–700 keV, 2–26 keV and 2–10 keV bands by the BeppoSAX satellite. In addition we present a novel scenario in which the supernova SN1998bw is the outcome of an “induced gravitational collapse” triggered by GRB 980425, in agreement with the GRB-Supernova Time Sequence (GSTS) paradigm [Ruffini, R., Bianco, C.L., Chardonnet, P., Fraschetti, F., Xue, S.-S. On a possible GRB-supernova time sequence. Astrophys. J. 555, L117–L120, 2001c]. A further outcome of this astrophysically exceptional sequence of events is the formation of a young neutron star generated by the SN1998bw event. A coordinated observational activity is recommended to further enlighten the underlying scenario of this most unique astrophysical system.     

Radioactivity of the Moon and planets

In this report the main results of the study of radioactivity of the solar sistem bodies are considered. The radioactivity of the Moon and planets was measured by means of vehicles in situ. The radioactivity of the lunar samples, brought to the Earth was studied with laboratory equipment.     

The Swift Ultra-Violet/Optical Telescope

The Ultra-Violet/Optical Telescope (UVOT) is one of three instruments flying aboard the Swift Gamma-ray Observatory. It is designed to capture the early (∼1 min) UV and optical photons from the afterglow of gamma-ray bursts in the 170–600 nm band as well as long term observations of these afterglows. This is accomplished through the use of UV and optical broadband filters and grisms. The UVOT has a modified Ritchey–Chrétien design with micro-channel plate intensified charged-coupled device detectors that record the arrival time of individual photons and provide sub-arcsecond positioning of sources. We discuss some of the science to be pursued by the UVOT and the overall design of the instrument.     

Investigating γ- and X-ray properties of GRBs using multivariate statistics

We propose to study the interrelation between the γ- (Fluence, 1sec Peakflux, duration) and X-ray (early X flux, 24 h X flux, X decay index, X spectral index, X HI column density) properties using the canonical correlation method. Computing the canonical correlations and variables we show that there is a significant interrelation between the γ- and X-ray data. Using the canonical variables from the analysis, we computed their correlations (canonical loadings) with the original ones. The canonical loadings revealed that the γ-ray fluence and the early X-ray flux give the strongest contribution to the correlation in contrast to the X-ray decay index and spectral index. An interesting new result appears to be the strong contribution of the HI column density to the correlation. Accepting the collapsar model of long GRBs this effect may be interpreted as an indication for the ejection of an HI envelope by the progenitor in the course of producing the GRB.