Problems, Connections and Expectations of Asteroseismology: a Summary of the Workshop

The workshop took place at the beginning of what promises tobe a golden age of asteroseismology.Ground-based instrumentation is finally reaching a level of stabilitywhich allows detailed investigations of solar-like oscillations in atleast bright, slowly rotating main-sequence stars.Very extensive results are expected from the coming space missions,including data on a broad range of stars from the Eddington mission.The observational situation is therefore extremely promising.To make full use of these promises, major efforts are requiredtowards the efficient utilization of the data, through the developmentof techniques for the analysis and interpretation of the data.A broad range of topics related to these issues is discussed in the presentproceedings. Here I review some of the relevant problems,relate the asteroseismic investigations to broader areas of astrophysics and consider briefly the basis for our great expectations for the developmentof the field.     

Trace element distribution during the reproductive cycle of female and male spiny and Pacific scallops, with implications for biomonitoring

Trace element concentrations and contents in gills, gonad, kidneys, mantle, muscle and remainder during the reproductive cycle of female and male spiny and Pacific scallops, from the Strait of Georgia, BC, Canada, were quantified by using ICPMS. The elements investigated were chromium, manganese, iron, cobalt, nickel, selenium, molybdenum, cadmium, tin and mercury. For all ten elements, the tissue distribution was to some extent influenced by species, sex and reproductive status. The implications of the present study in relation to the design of biomonitoring programmes are: (1) care should be taken to ensure an equal/constant sex composition when making interannual comparisons of pooled samples. Preferably the sexes should be monitored separately. (2) the practice of obtaining pooled samples in the interspawn phase is applicable only to monitoring long-term trends in contaminant levels, while the reproductive status should be heeded when studying short-term changes. (3) the present study confirms that direct temporal or spatial comparisons of absolute accumulated element concentrations are only valid intraspecifically.     

Rocket-borne and groundbased observations of coincident field-aligned currents,electron beams,and plasma density enhancements in the afternoon auroral oval

Results are reported from a rocket experiment conducted at Søndre Strømfjord, Greenland, on 22 August 1976, at 16.00 M.L.T. A series of plasma, particles, and fields and wave experiments were carried on board the payload, and the venture was supported by data from the AE-C satellite and by groundbased ionosondes and magnetometers at the launch site and at Godhavn. Two regions of field-aligned electron precipitation, electron density and temperature enhancements, and field-aligned upflowing current sheets were intercepted by the rocket. The density enhancements were also observed by groundbased ionosondes. Significant discrepancies were found between the currents carried by the streaming electrons in the 0.15–10 keV range and the upflowing currents seen by the on board magnetometer, suggesting that the upflowing current could not be the primary driver of the electron acceleration mechanism. The E-region was unstable to the combined Gradient-Drift and Farley-Buneman instability, and plasma turbulence was observed in situ, but the absolute density fluctuations were too small to return detectable HF-radar power to the ground.     

Limnic Responses to Increased Effective Humidity during the 8200 cal. yr BP Cooling Event in Southern Sweden

Highly resolved sediment stratigraphic and stable isotope records from a lake in south-central Sweden give evidence of relatively humid summers during the wide-spread cold event at c. 8200 cal. BP. A transient lake-level rise led to increased catchment erosion followed by enhanced phytoplankton production and disturbance of the Chara-dominated algal community. An associated increase in the deposition of organic material resulted in hypolimnetic oxygen deficit and methane formation as inferred from elevated sulphur content of the sediments and strong depletion in ¹³C of bulk organic material. In combination with dry and cold winter conditions as revealed by other proxy records, these data suggest the development of a strongly seasonal climate in northwestern Europe in response to altered atmospheric circulation at this stage. Enhanced zonal circulation with frequent cyclonic activity and increased effective humidity probably characterized the summer climate of southern and central Scandinavia, consistent with conditions inferred for continental Europe. In contrast, the winter climate was dominated by blocking high-pressure circulation, giving rise to cold and dry conditions.     

Galactic longitude dependence of the intensity ratio of the diffuse interstellar absorption bands at λλ6180 and 4430

Equivalent widths, as published by Seddon, for the diffuse interstellar absorption band at 6180 are compared with photoelectric 4430 indices for ten stars in the northern Milky Way. The intensity ratio is found to depend on galactic longitude in a way similar to that found by Johnson for the ratioA _V /E _B–V of total to selective interstellar absorption.The dependence found, combined with deductions from a tentative identification of the bands as due to negative hydrogen, points to a direction for the galactic magnetic field that is in better agreement with the direction derived from rotation measures of extragalactic sources than with that based on the dust-hypothesis interpretation of interstellar optical polarization.     

The 1s 2s states of negative hydrogen

Term values for the 1s 2s states of H^– are calculated with the use of simple eigenfunction approximations constructed on the basis of available Hartree-type functions for the 1s ² and 2s ² states of the ion. The results seem to support a tentative identification of the interstellar diffuse absorption bands at 4890 and 6180 as due to negative hydrogen.     

Polar 5—an electron accelerator experiment within an aurora. 4. Measurements of the 391.4 nm light produced by an artificial electron beam in the upper atmosphere

The POLAR 5 sounding rocket, launched from Andøya, Norway, on February 1, 1976, was of the “mother-daughter” configuration.A rocket-borne electron accelerator, mounted on the “daughter,” produced a pulsed electron beam with a maximum current of 130 mA and electron energies up to 10 kev.Using a photometer the luminescence at 391.4nm produced by electrons colliding with ambient nitrogen molecules was studied. The observed light at 391.4 nm consisted of low background, with occasional flashes due to the natural auroral excitations, and intense sparkles when the electron beam was emitted.Below 130 km the light observed during beam injection can be explained by excitations of ambient N₂ due to high energy beam electrons.In the altitude range from 150 km to apogee at 220 km, the observed light level during beam emission is fairly constant and much larger than that produced by the high energy beam electrons. A possible source of this light is the excitation of ambient N₂ by an enhanced population of low energy electrons, created by the presence of a beam plasma discharge in the vicinity of the “daughter” payload.     

Challenges in global ballast water management

Ballast water management is a complex issue raising the challenge of merging international regulations, ship's specific configurations along with ecological conservation. This complexity is illustrated in this paper by considering ballast water volume, discharge frequency, ship safety and operational issues aligned with regional characteristics to address ecological risk for selected routes. A re-estimation of ballast water volumes gives a global annual level of 3500 Mton. Global ballast water volume discharged into open sea originating from ballast water exchange operations is estimated to approximately 2800 Mton. Risk based decision support systems coupled to databases for different ports and invasive species characteristics and distributions can allow for differentiated treatment levels while maintaining low risk levels. On certain routes, the risk is estimated to be unacceptable and some kind of ballast water treatment or management should be applied.