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The simplest version of the method of detection of single molecular scattering basing on the polarization measurements of the twilight sky background by all-sky cameras is considered. The method can be used during the transitive twilight…
The determination of the cutoff frequency in real solar observations under different local physical conditions is an important and insufficiently explored aspect of waves in solar physics. This work utilizes the near ultraviolet (NUV)…
Electric field measurements of the Time Domain Sampler (TDS) receiver, part of the Radio and Plasma Waves (RPW) instrument on board Solar Orbiter, often exhibit very intense broadband wave emissions at frequencies below 20~kHz in the…
Recently an accurate analysis of absorption spectra of molecular hydrogen, observed with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope, in the photosphere of white dwarf stars GD133 and GD29-38 was published in a Letter…
Forthcoming experiments will enable us to determine tomographic shear spectra at a high precision level. Most predictions about them have until now been biased on algorithms yielding the expected linear and non-linear spectrum of density…
We measure seeing-corrected ellipticities for 2 x 10^6 galaxies with magnitude R<23 in 12 widely separated fields totalling 75 deg^2 of sky. At angular scales >30\arcmin, ellipticity correlations are detected at high significance and…
We introduce a new method to determine the relative contributions of different types of stars to the integrated light of nearby early-type galaxies. As is well known, the surface brightness of these galaxies shows pixel-to-pixel…
Treatments of the radio scattering due to density turbulence in the solar wind typically employ asymptotic approximations to the phase structure function. We use a general structure function (GSF) that straddles the asymptotic limits and…
Variation in total solar irradiance is thought to have little effect on the Earth's surface temperature because of the thermal time constant--the characteristic response time of the Earth's global surface temperature to changes in forcing.…
The continuum intensity at wavelengths around 1 mm provides an excellent way to probe the solar chromosphere. Future high-resolution millimetre arrays, such as the Atacama Large Millimeter Array (ALMA), will thus produce valuable input for…
Exoplanet emission spectra are often modelled assuming that the hemisphere observed is well represented by a horizontally homogenised atmosphere. However this approximation will likely fail for planets with a large temperature contrast in…
The existence and origin of large spatial temperature fluctuations in HII regions and planetary nebulae are assumed to explain the differences between the heavy element abundances inferred from collisionally excited and recombination lines,…
In stratified atmospheres, acoustic waves can only propagate if their frequency is above the cutoff value. Different theories provide different cutoff values. We developed an alternative method to derive the cutoff frequency in several…
The frequencies of solar oscillations are known to change with solar activity. We use Principal Component Analysis to examine these changes with high precision. In addition to the well-documented changes in solar normal mode oscillations…
Frequency and rotational splittings of the solar f-modes are estimated from the GONG data. Contrary to earlier observations the frequencies of f-modes are found to be close to the theoretically computed values for a standard solar model.…
A reasonable basis for future astronomical investigations of exoplanets lies in our best knowledge of the planets and satellites in the Solar System. Solar System bodies exhibit a wide variety of surface environments, even including…
Earth's atmosphere imprints a large number of telluric absorption and emission lines on astronomical spectra, especially in the near infrared, that need to be removed before analysing the affected wavelength regions. These lines are…
We have examined the global structure of the solar magnetic field using data from the FeI spectral line at {\lambda}5250.2{\AA} obtained at the 150-foot tower telescope at the Mt. Wilson Observatory (MWO). For each point on the solar…
The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the…
Long-term modulation of solar differential rotation was studied with data from Mt. Wilson and our original observations during Solar Cycles 16 through 23. The results are: i) The global B-value (i.e. latitudinal gradient of differential…