On small active region filaments,fibrils and surges

High resolution Hα images and magnetograms (0.2 arc s) of an active region were obtained in alternating time series at 42 s cadences using the Swedish 1-m Solar Telescope on 2004 August 21. The Hα filtergrams reveal an active region filament and surges consisting of thread-like structures which have widths similar to the widths of chromospheric fibrils, both recorded down to the resolution limit in the best images. All observed structures in the active region appear highly dynamic. Fibrils show counterstreaming strongly resembling the counterstreaming threads in filaments.     

Nondestructive testing of honeycomb structures by computerized,thermographic systems

Complex honeycomb space structures (i.e. antennas, solar panels, etc.) must be inspected and accurately tested before flight.The thermography can be employed with success for the detection of the position of defects (delaminations, noneffective bondings, cracks, etc.) and for the evaluation of their size and geometry in all the cases in which the defect acts as a thermal resistance due to the low conductivity of the air filling the defect volume.The basic idea is to create in the specimen a heat flow distribution that is altered by the presence of the defect.The surface temperature distribution is then measured by means of a thermograph and is correlated with the presence of the defect.A numerical analysis and preliminary experiments have been carried out which show the feasibility of the method as applied to honeycomb structures.     

A high quality low state observation of Cir X-1

Cir X-1 was extremely faint when we observed it with EXOSAT. The light curve clearly shows the source in two states; a faint variable state and a very faint but more constant state. The spectrum is very complicated but clearly shows the existence of an iron line.     

Energy conversion of the flare due to direct electric fields from the sheared reconnection

In this paper we present a new mechanism of the main energy conversion of the solar flare. Since a flare inducing prominence (flux tube) rises V_z ? 300 km s⁻¹, the plasmas below it cannot continuously eject with Alfvén speeds of V_A = 3000 km s⁻¹ but probably with V_z ≈ ±100 km s⁻¹. Plasma up and downflows with V_A will within a short duration be blocked between the chromosphere where reconnected flux tubes are piling up, and the slowly rising flux rope. Hence the Petschek slow shock mechanism is difficult to be realized as a major energy converting mechanism.     

Kinetic cyclotron and synchrotron maser instabilities: Radio emission processes by direct amplification of radiation

This article reviews the theory of the kinetic (cyclotron an synchroton) maser instabilities. The subject has been extensively developed in recent years by many authors, who have been incited by the research of the auroral kilometric radiation and other applications. The maser mechanism is appealing because it is simple and efficient, and can lead to direct amplification of radiation. Two types of electron distribution functions have been investigated so far. These are the loss-cone and hollow-beam distributions which may exist pervasively in many regions within and beyond the solar system. It is likely that the maser instabilities can have many potentially important applications to numerous radio emission processes observed in astrophysical research.     

A two-dimensional position-sensitive spectroscopic proportional counter for balloon-borne hard X-ray astronomy

A new design of position sensitive spectroscopic proportional counter is described, for use in a balloon borne hard x-ray telescope. Initial position and spectral resolution data from a one-dimensional laboratory prototype are reported. With this device, the final telescope will have an angular resolution of better than 10 minutes of arc.     

Design study for a three-meter balloon-borne telescope for far infrared and submillimeter astronomy

A NASA supported design study is being carried out for a three-meter balloon-borne far infrared and submillimeter telescope. The goal of this project is to provide a facility for frequent flights for photometry, spectroscopy, and imaging in the spectral region 30 micrometers to 1 millimeter. It is intended to provide a scientific and technical step on the way to a large submillimeter telescope in space in the future. The study is concentrating on areas where technical advances are required: materials and fabrication techniques for lightweight primary mirrors, telescope and gondola structure, and pointing and stabilization. We are carrying out a design optimization and environmental test program of state-of-the-art carbon fiber reinforced plastic sandwich panels in collaboration with Dornier Systems. Similar efforts are being pursued for very lightweight molded glass mirrors. Innovative approaches to the telescope support and stabilization are being explored for achieving the required 1 arcsecond pointing stability.     

Preliminary results of Cytos 2 experiment.

Cytos 2 experiment, carried out during the French-Soviet manned flight (July 1982), has studied the antibiotics sensitivity of bacteria cultivated in vitro during the orbital flight. The results show an increase of the antibiotics resistance and a larger thickness of the cellular envelope for the inflight cells. The increase of antibiotics resistance can be related to a stimulating effect of space on the cell growth rate or to changes of the cellular envelope structure.     

Investigation of natural and artificial stimulation of the ionospheric Alfvén resonator at high latitude

A brief review is provided of recent progress in understanding the ionospheric Alfvén resonator (IAR) at high latitude. Firstly, naturally occurring resonances of the IAR as detected by pulsation magnetometers in the auroral zone at Sodankylä and in the polar cap at Barentsburg are considered. The characteristics of the IAR in the two regions are broadly similar, although the effects of solar illumination are less clear at the higher latitudes. Secondly we review recent attempts to stimulate the IAR through high-power radio frequency experiments both in the auroral zone at Tromsø with the European Incoherent SCATter (EISCAT) heater, and within the polar cap at Longyearbyen with the Space Plasma Exploration by Active Radar (SPEAR) facility. In the auroral zone at, Tromsø the stimulated IAR has been observed by ground-based magnetometers, and through electron acceleration observed on the FAST spacecraft. At SPEAR in the polar cap, the stimulated IAR has been investigated, with ground magnetometers, with the first results indicative of a positive detection.     

Recent results on the Venus atmosphere from pioneer Venus radio occultations

Radio occultation measurements of the temperature structure of the Venus atmosphere have been obtained during seven occultation “seasons” extending from December 1978 to December 1983. Approximately 123 vertical profiles of temperature from about 40 km to about 85 km altitudes have been derived. Since these measurements cover latitudes from both poles to the equator, they have shown the latitudinal dependence of thermal structure. There is a smooth transition from the troposphere to the mesosphere at latitudes below about 45°, with the tropopause at about 56 km. The troposphere then rises to about 62 km in the “collar cloud” region between about 60° and 80° latitude, where a strong temperature inversion (up to 30 K) is present. In the polar areas, 80°–90°, the mesosphere becomes isothermal and there is no inversion. This latitudinal behavior is related to the persistent circulation pattern, in which a predominantly zonal retrograde motion at latitudes below 45° gradually changes to a circumpolar vortex at the “collar cloud” latitudes. Indeed, the radio occultation data have been used in a cyclostrophic balance model to derive zonal winds in the Venus atmosphere, which showed a mid-latitude (50°–55°) jet with a speed of about 120–140 ms^?1 at about 70 km altitude /1,2/. The observations obtained in 1983 and 1984 have shown that above the tropopause there is considerable temporal variability in the detailed thermal structure, suggesting that the persistent circulation pattern is subject to weather-like variability.