A Study of Correlation between Solar Wind Data Observed at Two Points in Interplanetary Space During the Recent Solar Maximum

Identifying co-rotating structures in solar wind enables us to predict solar wind variation at the Earth and, hence, geomagnetic disturbances. However, co-rotating structures during solar maximum are sometimes difficult to see. We correlated solar wind data obtained by two spacecraft, Nozomi heading towards Mars and ACE at the L1 point, from late 1999 through early 2002. There were intervals when the solar wind showed specific co-rotating structures even in the midst of the solar maximum, whereas no correlation was found during the other intervals. The coefficient was generally higher between Nozomi and ACE than for the 27-day recurrence at ACE, while there was some correlation, especially when the difference in longitude between the two spacecraft was less than 120°. Although frequency of occurrence of CMEs is partly responsible for the correlation, the results can be interpreted in terms of rapid changes in co-rotating high-speed streams from near-equatorial coronal holes at the solar maximum.     

Non-ducted two-hop whistlers in the inner magnetosphere deduced from rocket measurement

The non-ducted whistler propagation in the inner magnetosphere is discussed using the broad-band VLF measurement on board the K-9M-26 rocket launched at 1703 hr JST on 24 August 1969 from Kagoshima Space Center (geomagnetic lat 20°N). A large number of whistlers which seemed to be two-hop whistlers originating in the northern hemisphere were observed. The main features of these whistlers are summarized: (1) their dispersion value is widely scattered in the range $\text{55–75}\text{sec}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, (2) their frequency spectra show a broad maximum in the frequency range 2–5 kHz and higher frequency components are likely to disappear. Attempts are made to interpret these properties in terms of ducted or non-ducted propagation. It is then found from the ray tracing studies that the measurements are satisfactorily explained by non-ducted propagation in the inner magnetospheric model with latitudinal density gradient such as the equatorial anomaly.     

Diffuse component of the cosmic far UV radiation and interstellar dust grains

The diffuse far UV radiation ( 1350–1480 Å) observed in the sky region ofl ^II180°, 0°b ^II40° is analyzed in connection with the distributions of stars and dust grains as well as with optical properties of grains. Its intensity (starlight+scattered light) is about 6×10^–7 erg cm^–2 sec^–1 sr^–1 Å^–1 in the direction ofb ^II0° andl ^II180°. The latitude dependence of the intensity is in approximate agreement with the plane parallel slab model of the galaxy with a reasonable set of parameters. The interstellar scattering gives an albedo close to unity and forward phase function of about 0.6, which are not inconsistent with the model of interstellar grains of Wickramasinghe. The upper limit of the extragalactic UV is 2×10^–8 erg cm^–2 sec^–1 sr^–1 Å^–1 in the same region of wave-length.     

The influence of the equatorial anomaly on the ground reception of non-ducted whistlers at low latitudes

It is the purpose of this paper to study whether the non-ducted propagation in the inner plasmasphere in the presence of the equatorial anomaly might be relevant to daytime whistlers observed on the ground at low latitudes. Realistic models of the equatorial anomaly simulating the satellite observations have been incorporated in the ray tracing computations. It is found that there are two different non-ducted modes able to penetrate through the ionosphere onto the ground; (1) whispering gallery mode around the anomaly field line which is trapped just by the outer boundary of the anomaly, and (2) pro-longitudinal (PL) mode at a latitude around 30° which is supported by the horizontal gradient in the tail of the anomaly. These modes may provide a new interpretation for some whistlers observed on the ground. The properties of these modes are examined in detail and then compared with those of ducted propagation. This study may be useful for distinguishing the propagation mode in future ground-based experiments.     

X-ray spectra of various bursts from the rapid burster

About 20 type-I bursts and 3000 type-II bursts were observed with Tenma and Hakucho in 1983. Spectral evolutions were analyzed for both types of bursts and results are presented.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.Purple Mountain Observatory, Academia Sinica, Nanjing, China.     

Hydrogen flicker and associated high-energy radiation

The accretion of matter onto stars formed by carbon-oxygen cores triggers hydrogen flicker. The development of hydrogen flicker and the shock generation associated therewith are discussed. If the matter thus ejected is halted by a dense gas surrounding a star, a corona of high temperature is formed. This may take place in dense planetary nebulae and is regarded as an origin of starlike X-ray sources. More violent hydrogen flicker takes place at white dwarfs and may be an origin of novae. Nuclear-reaction products ejected are positron sources and they may provide MeV positrons as strong as 10^–3 cm^–2 sec^–1 sr^–1. Nuclides produced by hydrogen flicker and a part of the carbon-oxygen core ejected may contribute to galactic cosmic rays; their chemical composition is like that observed in cosmic rays.     

Does air ionization by radon cause low-frequency atmospheric electromagnetic earthquake precursors?

Natural Hazards - The aim of this work is to study the relationship between the pre-earthquake emissions of radon and ULF/ELF (1–30&nbsp;Hz) atmospheric electromagnetic radiation. The...