The normalized variance and power spectrum of the atmospheric scintillation has been measured above the Observatorio de Teide (Canary Islands), at 2400-m altitude, in the NIR atmospheric windows, J, H, K and L, using a 50-cm-aperture telescope. Observations were made between zenith distances 9 and 81 deg. The dependence on wavelength and air mass

Infrared photometry in J,H,K,L,M bands carried out in different years from 1983 to 1986, and U,B,V,R,I quasi-simultaneous to 1984 are presented. Although the amplitude of the minima decrease as the wavelength increase, the infrared light curves show a similar behaviour to that observed in visible. Since no variations in the average magnitudes are

The jump conditions across a shock front in a thin magnetic flux tube are studied by purely analytical means. Some properties of magnetohydrodynamic shock waves in extended media are shown also to hold in the more complicated case of thin magnetic flux tubes. It is shown that flux tube shock waves are always compressive, thus being accompanied by a

The contrast of the photospheric granulation in the centre of the disk at a wavelength of 500 nm has been determined by means of photographs taken during the solar eclipse of May 30th 1984. After restoration, values of 17.3% and 20.4%, using the sum of two lorentzians to define the instrumental profile, and of 11.7% and 14.3%, using the sum of two

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The authors discuss the nature of S 201 in the light of new optical and infrared observations, in terms of the interaction between an evolved H II region and a nearby molecular cloud. The energetics of the region and the role of star formation in that area are also briefly discussed.