Oxygen line mapping of SN 1006 with Suzaku

SN 1006 is one of the supernova remnants (SNRs) with relatively low-temperature electrons, considering the young age of just 1000 years. We carried out SN 1006 mapping observations with the X-ray Imaging Spectrometers (XIS) and the Hard X-ray Detector (HXD) onboard Suzaku, the fifth Japanese X-ray satellite. Thanks to the excellent spectral resolution of XIS in the soft X-ray band, H-like and He-like oxygen emission lines were clearly detected, and we could make a map of the line intensity, and as well as a flux and the photon index of nonthermal component. We found that these parameters have spatial dependences from region to region in the SNR; the north region is bright in nonthermal, while dim in thermal; the east region is bright in both nonthermal and thermal; the inner region shows dim nonthermal and bright thermal emission. The photon index is the smallest in the north region.     

Geomagnetic pulsations

Conclusion In writing this review paper the author has been aware that although the present international classification on geomagnetic pulsations (see Table I) had been really useful for several years since the Berkeley Meeting, it seems unsuitable for the up-to-date pulsation study. This is mainly due to the fact that it depends only on the period and waveform of the pulsations. For example, (1) occurrence of PP type of Pc1 even in the international Pc3 range (Heacock, 1966), (2) PP and CE getting mixed in a common period band (cf. 2.7), (3) similar mixing tendency of Pc3 with Pc4 (cf. 3.3 or Figure 21), (4) subtypes of Pi pulsations having common period ranges but different source mechanisms, (5) existence of various types of pulsations which can be classified neither to Pc nor to Pi (cf. Section 6), and so on. Hence the author feels that a new pulsation classification based on physical image on the occurrence models is really needed now.According to the international definition which has a period range of pulsations from 0.2 (5 Hz) to 600 sec, a part of the following electromagnetic field fluctuations called ELF emissions and ELF whistlers should belong to geomagnetic pulsations. ELF emissions are at times observed near 4 Hz and 9 Hz. They are so termed because of the difference between these frequencies and the Schumann resonance frequencies of 8 and 14 Hz (Yanagihara and Shimizu, 1969; Polk, 1969). Another type, ELF whistlers, exhibit either rising, falling or fluctuating tones from about 2 Hz to probably a few tens of Hz (Duffus, Nasmyth et al., 1958; Yamashita, 1967; Glangeaud, 1967; Yanagihara and Shimizu, 1969). In this review paper, however, both ELF emissions and whistlers have not been reviewed, since most of these seem to be out of the international frequency range so far as present observational knowledge is concerned. Some of the Pc6 and Dp2, involved in the international period range of pulsations, have also not been commented on, but the reader is advised to refer to Herron (1967) and Nishida (1968), respectively, for more detail.It has been frequently pointed out in this paper that latitudinal dependence of pulsation amplitude is one of the most important clues for seeking the model of excitation and propagation of HM and EM waves, but that this dependence has not been precisely obtained so far owing to the difference in geomagnetic longitude of the pulsation stations (for example, see Figure 40). Cooperative observations based on standardized magnetometers are eagerly desired at stations which are densely arranged along the same magnetic meridian, even if the observation is temporal.As already reviewed, various conflicting models have been proposed for each type of pulsation. On the occurrence of pc's, for example, there are two main conflicting models. In the first model, Pc2, 3, and 4 (Troitskaya, 1967; Patel and Hastings, 1968; and others) or Pc3 and 4 (Radoski and Carovillano, 1966) are related to one and the same resonance system and the difference in the type of these pc's is attributed to an effect of geomagnetic activity on the size of this system. In the second model, Pc2, 3, 4 and 5 are related to three or four different resonant systems (Jacobs and Sinno, 1960b; Hirasawa and Nagata, 1966; Kato, Mori et al., 1968; and others). Most of the conflict among such models seems to be removable by combining more thorough theoretical studies and correct dynamic spectrum analyses of the data at the polar region, auroral zone, sub-auroral zone, and middle and low latitudes, for various geomagnetic disturbance conditions.     

New insights into SNR evolution revealed by the discovery of recombining plasmas

We report the discovery of recombining plasmas in three supernova remnants (SNRs) with the Suzaku X-ray astronomy satellite. During SNR’s evolution, the expanding supernova ejecta and the ambient matter are compressed and heated by the reverse and forward shocks to form an X-ray emitting hot plasma. Since ionization proceeds slowly compared to shock heating, most young or middle-aged SNRs have ionizing (underionized) plasmas. Owing to high sensitivity of Suzaku, however, we have detected radiative recombination continua (RRCs) from the SNRs IC 443, W49B, and G359.1–0.5. The presence of the strong RRC is the definitive evidence that the plasma is recombining (overionized). As a possible origin of the overionization, an interaction between the ejecta and dense circumstellar matter is proposed; the highly ionized gas was made at the initial phase of the SNR evolution in dense regions, and subsequent rapid adiabatic expansion caused sudden cooling of the electrons. The analysis on the full X-ray band spectrum of IC 443, which is newly presented in this paper, provides a consistent picture with this scenario. We also comment on the implications from the fact that all the SNRs having recombining plasmas are correlated with the mixed-morphology class.     

Solar power sail membrane prototype for OKEANOS mission

This paper reports on the manufacturing and evaluation of a solar power sail membrane prototype for the OKEANOS project. The in-house prototype was built by the Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency. Mechanical and electrical evaluation tests were conducted. The membrane, thin-film solar cells, reflectivity control devices were good condition after the manufacturing and handling. The improvements in the manufacturing process and design were found. The manufacturing process and design were fundamentally established. After the prototype, improvement plans for the manufacturing process and design were tried. We have a prospect of manufacturing the flight model sail and continue to the development.     

The Lunar Radar Sounder (LRS) Onboard the KAGUYA (SELENE) Spacecraft

The Lunar Radar Sounder (LRS) onboard the KAGUYA (SELENE) spacecraft has successfully performed radar sounder observations of the lunar subsurface structures and passive observations of natural radio and plasma waves from the lunar orbit. After the transfer of the spacecraft into the final lunar orbit and antenna deployment, the operation of LRS started on October 29, 2007. Through the operation until June 10, 2009, 2363 hours worth of radar sounder data and 8961 hours worth of natural radio and plasma wave data have been obtained. It was revealed through radar sounder observations that there are distinct reflectors at a depth of several hundred meters in the nearside maria, which are inferred to be buried regolith layers covered by a basalt layer with a thickness of several hundred meters. Radar sounder data were obtained not only in the nearside maria but also in other regions such as the farside highland region and polar region. LRS also performed passive observations of natural plasma waves associated with interaction processes between the solar wind plasma and the moon, and the natural waves from the Earth, the sun, and Jupiter. Natural radio waves such as auroral kilometric radiation (AKR) with interference patterns caused by the lunar surface reflections, and Jovian hectometric (HOM) emissions were detected. Intense electrostatic plasma waves around 20 kHz were almost always observed at local electron plasma frequency in the solar wind, and the electron density profile, including the lunar wake boundary, was derived along the spacecraft trajectory. Broadband noises below several kHz were frequently observed in the dayside and wake boundary of the moon and it was found that a portion of them consist of bipolar pulses. The datasets obtained by LRS will make contributions for studies on the lunar geology and physical processes of natural radio and plasma wave generation and propagation.     

An Adaptive Antenna for Rejection of Wideband Interference

A modification to the adaptive array under the directional constraint [1] is proposed to improve its performance of rejecting wideband interference. By analogy to the pattern synthesis of an antenna array which produces a flat null in its radiation pattern, an additional quantity that corresponds to the derivative of the pattern is generated and combined with the standard feedback quantity to control the weights of the array. This composite system is tested by computer simulation experiments and the following points are demonstrated in contrast to the conventional, simple system: 1) faster adaptation against wideband interference, 2) remarkable improvement of the signal-to-noise ratio of the output, i. e., very small fluctuation.     

KIBO (Japanese Experiment Module in ISS) operations—2008/3–2009/10

Japan Aerospace Exploration Agency (JAXA) launched its own first manned experiment facility in space called the KIBO (Japanese Experiment Module, JEM) in 2008 and 2009 and started operations as part of International Space Station (ISS). To accomplish this Operation, JAXA made its own ground facility in Tsukuba, Japan, called Space Station Integration and Promotion Center (SSIPC). Ground personnel at SSIPC called the JEM Flight Control Team (JFCT) operate the KIBO and have learnt many lessons during its operation. In this presentation, some topics are chosen and explained such as (1) crew/ground personnel interaction and (2) planning lessons learned for manned space activities.     

A state-of-the-art review in radar polarimetry and its applicationsin remote sensing

The authors assess the state of the art, focusing on their own contributions. Covered areas are the electromagnetic inverse problem in radar polarimetry, coherent polarization radar theory, partially coherent polarization radar theory, vector (polarization) inverse scattering approaches, the polarimetric matched filter approach, polarimetric Doppler radar applications in meteorology and oceanography, and image fidelity in microwave vector diffraction tomographic imaging     

Long-period irregular magnetic pulsation,Pi3

In the 1973 Scientific Assembly, the International Association of Geomagnetism and Aeronomy proposed with Resolution No. 11 to settle two new classes of magnetic pulsations; Pc6 having a sinusoidal waveform with periods longer than 600 s and Pi3 having an irregular waveform with periods longer than 150 s. The present paper reviews the studies on these pulsations putting a stress on Pi3. the Pi3-type pulsations are further classified into Psc5, Psc6, Pip, Ps6 and another type. The pulsations Psc5 and Psc6 mean the damped-type pulsations associating with storm sudden commencement in the approximate period range from 150 to 600 s and longer than 600 s, respectively, while Pip and Ps6 are the quasi-sinusoidal pulsations associating with magnetospheric substorm in the appropriate period range from 100 to 400 s and from 5 to 40 min, respectively. In the present review paper a stress is further layed on morphology and theory of the Ps6-type Pi3 pulsation. The following two-snake model is concluded to be plausible. A current system with in-flowing field-aligned current, westward ionospheric current, and out-flowing field-aligned current expands toward both the dawn- and the dusk-sectors with the progress of magnetospheric substorm. Thus Ps6 is regarded to be due to a magnetic effect of a meandering of the current system during the expansion, which is compared with the meandering of two snakes along the auroral oval from the midnight point toward both the east and the west, respectively.