Possible shrinking of the primary component of epsilon aurigae

Radial velocities of the primary star of Aur are presented for phases outside the eclipse between 1975 and 1985. A violent collapse of the atmosphere has occurred with a velocity of about 40 km s^–1 on October 1977, indicating a decrease of 0.07 AU in the radius for three days. A shrinking of the primary star is suggested from the characteristics of eclipse light curves that the duration of totality has become longer and the duration of eclipse shorter from eclipse to eclipse. The decrement of radius is estimated to be about 16%, 0.2 AU, in recent 27 years.     

A far-infrared H-R diagram of young stellar objects

The observed spectral energy distributions from far-infrared (FIR) to millimeter wavelengths of young stellar objects (YSOs) fit a modified blackbody radiation with a peak around 100 m for both high-and low-mass YSOs. The spectra are nearly represented by the FIR colors made byIRAS flux densities at 60 and 100 m. UsingIRAS data, we make a FIR H-R diagram of cold YSOs, the parameters of which are the FIR color and the luminosity at 60 m. In each FIR H-R diagram of YSOs of three nearby star-forming regions, YSOs in early evolutionary phase form a fundamental sequence, along which they move with increasing of the luminosity while keeping the mass of FIR emitting envelope. We can predict the stellar masses of YSOs by using the H-R diagram.     

Convective instability and overstability in the sunspot umbra

Convective instability and overstability of a plane-parallel medium in the presence of a uniform vertical magnetic field is studied. We take into account both the effect of penetration of disturbances into sub-adiabatically stratified semi-infinite upper and lower layers, and the effect of thermal damping of disturbances introduced by the compressibility of the medium. If the degree of super-adiabaticity in temperature stratification in the middle layer is relatively large compared with that of sub-adiabaticity in the upper and lower layers, the range of physical conditions in which overstable convection occurs is very narrow. However, if it is not the case the range is rather wide. In the normal sunspot umbra, only disturbances with selected sizes in vertical dimension will be able to become overstable. The overstable convection might be a cause of some dynamical features (such as dots) in the sunspot umbra, but will not be the main contributor for transporting mechanical energy in the sunspot region.     

An expanding circumstellar cloud of Zeta Aurigae

Strong absorption satellite lines of CaI 6572 were found on spectrograms taken on three successive days just after the fourth contact of the 1971–72 eclipse of Zeta Aurigae. The radial velocities of the satellite lines are –88 km s^–1, –74 km s^–1, and –180 km^–1, respectively, relative to the K-type primary star (K4 Ib). These absorptions should be due to a circumstellar cloud in which the column density of neutral calcium atoms is 1×10¹⁷ cm^–2 and the turbulent velocities come to 20–50 km s^–1. It is suggested that the cloud may be formed by the rocket-effect of the Lyman quanta of the B-type component (B6 V). We estimate the density in the cloud to be 2×10¹¹ atoms cm^–3 fors=10R _K and 2×10¹⁰ atoms cm^–3 fors=10² R _K, wheres denotes the distance of the cloud from the K star andR _K the K star's radius. The mass loss rate of the K-type component is also estimated to be about 10^–7 M yr^–1, assuming that the expansion of the K star occurs isotropically.     

The effects of season on fatty acid composition and ω3/ω6 ratios of northern pike(Esox lucius L.,1758) muscle lipids

In the present study,the effects of season on fatty acid composition,total lipids,and ω3/ω6ratios of northern pike muscle lipids in Kizilirmak River(Kirikkale,Turkey) were investigated.A total of 35 different fatty acids were determined in gas chromatography.Among these,palmitic,oleic,and palmitoleic acids had the highest proportion.The main polyunsaturated fatty acids(PUFAs) were found to be docosahexaenoic acid,eicosapentaenoic acid,and arachidonic acid.There were more PUFAs than monounsaturated fatty acids(MUFA) in all seasons.Similarly,the percentages of ω3 fatty acids were higher than those of total ω6 fatty acids in the fatty acid composition.ω3/ω6 ratios were calculated as 1.53,1.32,1.97,and 1.71 in spring,summer,autumn and winter,respectively.Overall,we found that the fatty acid composition and ω3/ω6 fatty acid ratio in the muscle of northern pike were significantly influenced by season.     

Circumstellar line of Cai λ6572 in Zeta Aurigae and 31 Cygni

In the 1974 eclipse of Zeta Aurigae the satellite line of the Cai intercombination line at 6572 Å appeared in all the phases observed, i.e., near the mid-eclipse and egress, although its equivalent width, 100–200 mÅ, and velocity deviation, –20 im s^–1, from the principal line were considerably less than those for the satellite line found just after the fourth contact of the 1971–72 eclipse. 31 Cygni also showed a similar satellite line to Zeta Aurigae's in the 1974 eclipse, not only in the 1972 eclipse but also outside the eclipse. These satellite lines should be due to the circumstellar gas expanding from the binary systems.     

Spectroscopic observations of zeta Aurigae during the 1971–72 eclipse

The chromospheric phases in the 1971–72 eclipse were observed at wavelength regions containing the K-line of ionized calcium on six nights at ingress and on eight nights at egress at the Okayama Astrophysical Observatory. The linear dispersion of the spectrograms is about 10 Å mm^?1. The spectrograms were measured for line intensities of the K-line and for radial velocities of metallic and hydrogen lines. The results are compared with those obtained in the earlier eclipses. The intensities of the chromospheric K-line during this eclipse were relatively ‘weak’ at both ingress and egress and were similar to those in the 1939–40 eclipse. It seems that the chromospheric activity of ζ Aurigae increased after 1939, reached a maximum at 1950–56, and then decreased again until 1971. The radial velocities of the chromospheric lines of hydrogen atoms, ionized calcium, and some other atoms and ions varied with phase showing almost the same characteristic features as in most earlier eclipses. Intensities and velocities were also measured for satellite lines of the K-line.     

Analysis of a magnetohydrodynamic stellar wind

Characteristic features of solutions are analysed around the Alfvénic point. There are three types of solutions through the point.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.     

Spatial and temporal characterization of standard duration-maximum precipitation over Black Sea Region in Turkey

Natural Hazards - This study characterises the spatial and temporal behaviours of maximum precipitation over the Black Sea Region in northern Turkey. Maximum precipitation data of 14 standard...     

A spectroscopic study of Epsilon Aurigae

Epsilon Aurigae has been observed during ingress and totality between 1982 and 1983 at Okayama. Analyses of profiles of H line and of radial velocities of neutral hydrogen and metals show that the secondary component consists of at least three parts in structure.Paper presented at the Lembang-Bamberg IAU Colloquium No. 80 on Double Stars: Physical Properties and Generic Relations, held at Bandung, Indonesia, 3–7 June, 1983.