Peculiarities of the mode of oscillations in a floccule and its neighborhoods at different chromospheric levels

The behavior of oscillations in the quite solar chromosphere under a coronal hole at several heights has been investigated. The properties of oscillations in cell, network, and weak-floccule areas have been analyzed. A time series of spectrograms in three ionized calcium lines, the Ca II K and H resonance doublet lines and the infrared Ca II 849.8-nm triplet line, was used. The observations were carried out at the horizontal solar telescope of the Sayan Observatory. The goal of this study was to compare the distributions of spectral power in various frequency ranges and their variations for selected spatial areas at different heights of the chromosphere. Particular attention was paid to the weak floccule due to a noticeable difference in the central intensity distribution between the K and H lines and the 849.8-nm line. A spectral Fourier analysis was used. The central intensities of the observed spectral lines, the K-index, and the equivalent width (the latter for the 849.8-nm line) were chosen as oscillation parameters. The studies have shown that the main intensity oscillation power at both atmospheric levels is concentrated at frequencies below 9 mHz. In the distribution of intensity oscillation power at different chromospheric levels, there are differences clearly distinguishable in the floccule. Powerful five-minute oscillations whose main peak frequency decreases with height, while the amplitude increases have been detected in the central part of the floccule. This result confirms the assumptions recently pointed out in the literature that vertical magnetic field concentrations can serve as a channel for the passage of low-frequency oscillations from the photosphere to the chromosphere in faculae. The intensity oscillation power in the frequency ranges under consideration has turned out to decrease with height, on average, for the entire observed spatial area. This may be related to the loss of part of the wave energy through the reflection, dissipation, and transformation of wave modes in the magnetic canopy layer. An area with a low brightness but powerful oscillations at about 3.3 mHz covering a considerable range of heights probably pertaining to “magnetic flashers” has been isolated in the telescope’s field of view.     

Magnetic field and radial velocity of the Ap star 52 Her. I. Observations,measurements, results

Since 1971 the magnetic Ap star 52 Her has been investigated with respect to its magnettic field and radial velocity on the observational basis of 140 photographic Zeeman spectrograms obtained at the 2m-telescope in Tautenburg. Additionally, 47 normal spectrograms were used for the determination of the radial velocity only. The technical foundation for observation and measurement is considered. The main purpose of the paper, however, is the documentation of the observations and the measuring results. Deductions drawn from the material assorted here or taken from other sources are put off to following papers.     

Intensity oscillations at the feet of coronal holes

We investigate the regime of chromospheric oscillations at the bases of coronal holes and compare them with the oscillations in the quiet chromosphere outside coronal holes using time series of spectrograms taken at different times in eight quiet regions on the Sun. As the oscillation parameter being studied, we have chosen the central intensity of the chromospheric Ca II K and H and 849.8-nm lines. The intensity measurements at all spatial points (along the spectrograph slit) have been subjected to a standard Fourier analysis. For the identified areas of the networks, cells, and network boundaries, we have calculated the integrated oscillation powers in several frequency bands. For all frequency bands, the powers of the intensity oscillations at the formation level of the Ca II resonance doublet line cores have been found to be enhanced at the bases of coronal holes approximately by a factor of 1.5. For the “three-minute” band, this enhancement is more pronounced in the network than in the cell, while the opposite is true for the “five-minute” band. The power in the five-minute band is higher than that in the three-minute one both at the bases of coronal holes and outside them, but this ratio in the network for a coronal hole is higher (1.40 ± 0.25 and 1.30 ± 0.10). We interpret this fact and the fact that the power of the three-minute oscillations for nonmagnetic regions changes with height differently at the base of a coronal hole and outside it as an increase in the importance of magnetoacoustic portals at the chromospheric base of the coronal hole.     

On fine structure of the magnetic field and brightness in the penumbrae of sunspots

From investigating spectrograms of penumbrae of some sunspots it is concluded that the maximum magnetic field strength occurs in dark filaments and amounts to 1800–1900 G; the intensity of the magnetic field in dark filaments is 100–400 G larger than in the neighbouring bright filaments; the bright filaments seen in the space between the dark features cannot be attributed to the ordinary undisturbed photosphere.     

Spectroscopic study of the Chemically Peculiar star HD 5797

Based on 19 spectrograms with a dispersion of 17.5 Å/mm, line spectrum variations in the CP2 star HD 5797 are studied. Equivalent width and central depth measurements show that intensities of 34 unblended lines vary with an amplitude of about 2 times for Fe, Ti and Sr lines, and 2.5 times for Cr lines. A search for improved period of the star has been carried out. The obtained new value is:P = 68.255 ± 0.004 days. An attempt to give a qualitative explanation of the photometric behaviour is made.     

Spatial structure in lines in the 3398–3526 å region at the extreme limb: Observation,identification and interpretation

We have obtained spectrograms of high spatial and spectral resolution of the extreme solar limb, using the vacuum tower telescope of Sacramento Peak Observatory. We have identified emission lines in the range 3398–3526 Å, and classified them according to intensity, spatial structure (intensity variation), and profile. Some lines show spatial intensity variation; others do not. We show that this effect is related to the abundance of the element responsible for the line and the mean lower-level excitation potential of interlocked lines. We explain the effect in terms of radiative interlocking with other lines, as well as the characteristic size of the volume contributing to the mean intensity.Also Five College Astronomy Department, Amherst, Mass. 01003, U.S.A.Operated by the Association of Universities for Research in Astronomy Inc. under contract with the National Science Foundation.     

Investigation of the spectroscopic variability of the Wolf-Rayet star HD 192163

Based on 24 high-resolution echelle spectrograms of the Wolf-Rayet star HD 192163 taken in 2005–2007 at the Cassegrain focus of the 2-m Zeiss-2000 telescope at the Shemakha Astrophysical Observatory (National Academy of Sciences of Azerbaijan), we have investigated the profiles of five emission lines: He II 4859, He II 5411, CIV 5808, He I 5875, (He II + Hα) 6560. We have analyzed the echelle spectrograms using the DECH20 code. Various emission line parameters have been determined: the equivalent widths, radial velocities, central intensities, and FWHMs. The violet wing of the He II + Hα emission band has been found to be variable (from 6496 Å to 6532 Å). Significant differences in the equivalent widths and radial velocities of the He II + Hα emission band in 2005 and 2007 were revealed. This can be a manifestation of long-term variations in the star HD 192163. We have confirmed that HD 192163 belongs to the WN6 spectral subtype.     

Continuous spectral observations of spicules

D₃ and H line spectrograms of spicules are analysed. The spectrograms are obtained with a specific device attached to the 53 cm coronagraph of Abastumani Astrophysical Observatory. Certain results are derived, based on the observational material consisting of 70 height series spectrograms taken over a period of 44 min in H line and 60 height series spectrograms taken over a period of 30 min in D₃. Each series involves 8 spectrograms reflecting the state of spicules at eight different heights in the chromosphere.     

The spectrum of the inner corona observed during the total solar eclipse of 30 May 1965

A series of spectrograms of the inner solar corona were obtained at the total solar eclipse of 30 May 1965 using a fast spectrograph with a circular slit that recorded the spectrum from 3000 to 9000 at all position angles around the limb simultaneously. In this paper absolute intensity is given as a function of position angle for the stronger lines and the continuum. In the coronal enhancement or condensation centered at heliocentric position angle 293°, absolute intensity is given for 34 forbidden emission lines and the continuum.     

Variation of Methane Absorption over the Jovian Disk from the Data of Zonal CCD Spectrophotometry

A comprehensive zonal spectrophotometry of Jupiter's disk was performed with a prism spectrograph and an ST-6V CCD camera mounted on the 1-m telescope at the Assy observatory in 1997 and 1998. In addition to the spectra of the central meridian and the equatorial belt, 10 sets of spectrograms of 37 to 39 of Jupiter's zones were recorded with a step of about 1.2 (each set contained the measurements of absorption bands for approximately 3200 points of Jupiter's disk). Based on these data, an atlas of zonal variations in the central depths R of the methane absorption bands in the wavelength range 560–950 nm is compiled and numerical-contour and 3D half-tone maps representing the distributions of R over the disk are constructed. For most zones, methane absorption changes slightly from the central meridian to the limb. The intensities of strong and moderate methane bands exhibit pronounced zonal variations, whereas the intensity of a relatively weak band at 619 nm varies more chaotically. This effect is likely due to the fact that, at the effective depth where the weaker bands are formed, the medium is more homogeneous, since the convective and turbulent mixing is more intense at this depth.     

Amplitude distributions of solar photospheric fluctuations

Amplitude distributions, which are nearly Gaussian, have been calculated for radial velocity, continuum brightness, spectral line equivalent width and spectral line central residual intensity fluctuations measured from high-dispersion high-resolution spectrograms taken at the center of the solar disk. The RMS and skewness S for each distribution have been calculated in a manner which allows testing of the homogeneity of the granulation pattern (i.e. variations in its statistics across the solar disk and with time). Pattern inhomogeneity across the disk is strongly indicated, and further evidence suggesting appreciable pattern persistence over time intervals 15 minutes is presented. The possibilities for investigations of S and its associated bi-spectrum are discussed. The qualitative values of S obtained are shown not to be due to unusually bright, rising granules (though a statistical tendency towards such granules is possible). An attempt to explain S for continuum brightness fluctuations in terms of the nonlinear effects of Planckian emission and opacity fluctuations in a stratified photosphere, leads to contradiction with the measured amplitude distributions, a contradiction which is probably due to an oversimplified treatment of radiative transfer in an inhomogeneous photosphere.     

On a sequence of remarkable fine structures in the type IV burst of 24 April, 1985

During the type IV burst on 24 April, 1985 we observed at 234 MHz an untypical, strong, nearly six hours lasting continuum emission incorporating several groups of broadband pulsations, zebra patterns, fiber bursts, and a new fine structure phenomenon. The power spectra of the groups of broadband pulsations reveal no simple structure. There is only one common periodic component between 0.3 s and 0.4 s. Slowly drifting chains of narrowband fiber bursts are described as a new fine structure by spectrograms and simultaneously recorded single frequency intensity profiles. A qualitative model of this new fine structure is suggested.     

Spectral analyses of solar photospheric fluctuations

Residual intensity fluctuation measurements within the wings of the 5183.6 Mgi b₁ line, obtained from two, high-resolution, high-dispersion, Sacramento Peak Observatory spectrograms, have been subtracted from intensity fluctuations in the adjacent continuum in order to isolate fluctuations associated exclusively with line formation. The useable spectral range for studying these lineformation fluctuations is restricted to wavelengths between 1040 and 7170 km because the subtraction increases the relative importance of noise and large-scale photographic variations across the spectrograms could not be completely removed. Power and cross-power (coherence and phase) spectra proved to be valuable diagnostic tools in isolating line-formation fluctuations.Over this spectral range, the line-formation fluctuations are characterized by flat power spectra as compared to those for continuum fluctuations, appreciable fluctuation rms relative to that for continuum fluctuations, and the necessity to multiply the wing fluctuations by a factor 0.95 _min 1.00 to most effectively isolate these fluctuations (Figures 3 and 4). That continuum fluctuations are modified in shape but otherwise not drastically changed in the line wings explains the flat spectrum. The relative rms's vary from 0.34 in the inner wing to 0.22 in the outer. The range of possible values for _min results from uncertainties in the photographic density-residual intensity calibration.     

Exact solution of the problem of diffuse reflection for a combination of Rayleigh and isotropic scattering

We consider the basic vector equation of transfer for radiation in a semi-infinite atmosphere for diffuse reflection which scatters radiation in accordance with the phase matrix obtained from a combination of Rayleight and isotropic scattering. This equation will give an integral equation for emergent intensity while subjected to the Laplace transform. The integral equation will give rise to the emergent intensity matrix on application of the Wiener-Hopf technique. This is an exact method.     

On the abundance of deuterium in the solar atmosphere

The newly determined upper limit abundance of deuterium from the spectrograms of the fourth flight of the SSO, D/H < 10^–5, confirms the data obtained from the spectrograms of the third flight.     

Spectral lines from photosphere to chromosphere,observed during the March 1970 eclipse; A first comparison with theory

A brief report is presented on observations of line profile variations in the transition region from the photosphere to the chromosphere, based on high-resolution eclipse spectrograms. We also show some computations for several lines whose behaviour agrees in general with the observations.     

Detection of blends in the vicinity of Zeeman lines

High resolution spectrograms taken in polarized light have revealed the presence of significant blending within the profiles of some important Zeeman multiplets of a large umbra. Wavelength and equivalent width of each depictable blend have been derived from the corrected spectrograms and some preliminary identifications have been made.     

Extragalactic Gamma Ray Excess from Coma Supercluster Direction

The origin of extragalactic diffuse gamma ray is not accurately known, especially because our suggestions are related to many models that need to be considered either to compute the galactic diffuse gamma ray intensity or to consider the contribution of other extragalactic structures while surveying a specific portion of the sky. More precise analysis of EGRET data however, makes it possible to estimate the diffuse gamma ray in Coma supercluster (i.e., Coma\\backslash A1367 supercluster) direction with a value of $I\left( {E>{30}\,{\rm MeV}} \right)\simeq{1.9}\times {10}^{-{6}} {\rm cm}^{-{2}} {\rm s}^{-{1}}$I\left( {E>{30}\,{\rm MeV}} \right)\simeq{1.9}\times {10}^{-{6}} {\rm cm}^{-{2}} {\rm s}^{-{1}} , which is considered to be an upper limit for the diffuse gamma ray due to Coma supercluster. The related total intensity (on average) is calculated to be ~5% of the actual diffuse extragalactic background. The calculated intensity makes it possible to estimate the origin of extragalactic diffuse gamma ray.     

Transit or occultation?

Published discussions of photometric observations of VZ Hya and CM Lac disagree as to whether the deeper eclipses are transits or occultations. The evolutionary histories of these systems are critically dependent on a resolution of the disagreement. The luminosity ratio of the components of VZ Hya, inferred from spectrograms, shows unequivocally that the deeper eclipse is a transit. The case of CM Lac is less definitive. While the photometric observations favor primary minimum as a transit, the ratio of the radii is close to unity, and neither the spectrograms nor the photometry leads to an unequivocal result. Some confusion in notation appearing in a discussion of the components of EI Cep is noted. In each of the three cases the observational evidence favors a straightforward evolutionary interpretation in which the more massive star is the larger.     

Hα Line Impact Linear Polarization Observed in the 23 July 2002 Flare with the Large Solar Vacuum Telescope (LSVT)

We present the results of studying the proton flare 2B/X4.8 on 23 July 2002, observed with the Large Solar Vacuum Telescope (LSVT) at the Baikal Astrophysical Observatory in spectropolarimetric mode with high spatial and spectral resolution. We have found some evidence for H?? line impact linear polarization, predominantly during the initial moments of the flare. For the H?? line 606 cuts were made along the dispersion in 53 spectrograms, and a polarization signal was found more or less confidently in 60 cuts (13 spectrograms). Polarization was mainly observed in one of the kernels of the flare. A particular feature of this kernel was that the H?? line was observed to show a reversal in the central part of this kernel, which created a dip in the kernel center in the photometric cut. The size of these dips and the size of the sites with the linear polarization coincide and are equal to 3??C?6?arcsec. The maximum polarization degree in this kernel reached 15?%. The direction of the polarization in the kernel is radial, except for the first two frames, where the direction of the polarization was both radial and tangential. Furthermore, we found an analogy between the effects observed at the chromospheric level in this kernel (polarization and depression in H?? line) and the temporal variation of the HXR sources.