The identification of the 3μ spectral feature in galactic infrared sources

We show that a 3 extinction feature in galactic infrared sources cannot be due to water-ice grains. Infrared spectra with a resolution of /=0.015 are in remarkably close agreement with the 2.5–4 extinction properties calculated for bacterial grains.     

Infrared imaging of Jupiter in the 8–14-micrometer spectral region

High spatial resolution images of Jupiter were produced on the Hale 200-in. telescope in August 1974 and October 1975. A programmable wobbling secondary was used to raster scan the planet with 64 by 64 1-arsec pixels. Images were made with broadband (8–14 μm) and several 1- and 2-μm wide filters. All images reveal a belt and zone structure similar to visible pjotographs. Belts, in the broadband data, appear to be about 2°K hotter than the zones, but contrast varies markedly in different parts of the 8–14-μm spectral region. The lowest belt-zone contrast is found in the hydrogen opacity dominated region at 12.5 μm, while images at 9.5 μm exhibit the greatest contrast. Isolated areas are observed to be as much as 4°K hotter than surrounding areas at 9.5 μm. This large contrast is probably due to variations in the distribution of the ammonia clouds in the upper atmosphere.     

Analysis of the intensities and profiles of the spectral line Mg xii 8.42 Å in the solar X-ray spectrum

High resolution profiles of the Mg xii 8.42 Å line in the solar X-ray spectrum were recorded from the Intercosmos 7 satellite. The Mg xii line intensity provides a sensitive indicator of the hot plasma content (T ? 3 × 10⁶ K) in coronal condensations and X-ray flare volumes. The ratio of the line intensity to the intensity of the adjacent continuum has been used to compute approximate thermal models of the emitting regions. For all the investigated coronal condensations the temperature distribution of plasma has been found to be a function monotonically decreasing with temperature. But for some X-ray bursts there occurred a distinct excess of the hot plasma of temperature between 6–10 × 10⁶K. FWHM values of the Mg xii line profiles have been used to estimate ion temperature in the emitting regions.     

DLA abundances in the CUBES’s spectral window

Absorption systems observed along the line of sights to distant quasars are observed at all redshifts and the full range of the electromagnetic spectrum is needed to recover the variety of transitions of different elements. However, some important elements are found within the Lyman forest and their absorption line profiles need to be analyzed against the presence of possible Ly-α contamination. Considering the cosmological evolution of the number density of hydrogen clouds, the probability to detect uncontaminated metal lines is higher in the UV-Optical region exploited by CUBES. The list of these elements includes some important ones such as D, H₂, O?i, N?i, O?vi, Ar?i, P?ii, C?ii, S?ii and B?ii. The determination of some of them in the Damped Ly-α galaxies and their astronomical interest are briefly discussed.     

Physical mechanisms of the spectral variability of α Orionis with IUE

We present a spectroscopic study of Mg II k&h emission lines in the 2000–3000 Å region of 91 high resolution IUE spectra of α Orionis obtained during the period 1978–1996. There are absorption and emission components on the blue sides of the k&h emission lines, these components may be coming from the dust envelope located inside the extended atmosphere of α Orionis. A set of 91 Mg II k&h emission lines have been identified and measured to determine their fluxes and widths. We found that there is a spectral variability for these physical parameters with phase, similar to that found for the light curve, which we attribute to the changes of density and temperature of the regions from which these emission lines are coming, as a result of the semi-regular pulsation and the variability of mass loss of the red supergiant.Also we present a study of C II and Fe II emission features in the 2000–3000 Å region of 55 high resolution IUE spectra during the period 1978–1996. A set of 55 C II and Fe II emission lines have been identified and measured to determine their fluxes and widths. We found the same result as with the Mg II emission lines.     

The material of the interstellar dust and the surface of asteroids: A comparison of the spectral properties in the 0.3–1.1-μm range

From the data on bright stars of different spectral and luminosity classes from the 13-color photometry catalog, the selective extinction of light by the interstellar dust has been studied. The stars from the 1000-pc vicinity of the Sun were investigated. In the optical spectral range, the interstellar extinction curves show systematic deviations from the “λ^?1” law, which allows one to sort them into three types. The observed curves of the interstellar dust extinction were compared with the theoretical curves calculated from the reflectance spectra of the asteroids under the approximation of the Rayleigh particles. The calculated extinction curves for the surface material of D-type asteroids and the Tagish Lake carbonaceous chondrite agree rather well with the observed curves of the interstellar extinction of the first type.     

On the signatures of companion formation in the spectral energy distributions of Sz54 and Sz59—the young stars with protoplanetary disks

We study spectral energy distributions of two young systems Sz54 and Sz59, that belong to Chameleon II star forming region. The results of the modeling indicate that protoplanetary disks of these systems contain gaps in the dust component. These gaps could be a result of a planetary or brown dwarf companion formation, because the companion would accumulate a disk material, moving along its orbit. In a present work we have determined physical characteristics of the disks. We also discuss possible companion characteristics, based on the geometrical parameters of the gaps.     

A search for the Hα emission in spectroscopic binaries of the spectral types B0–B9

The H emission is searched for 67 spectroscopic binaries of the spectral types B0–B9 and of the orbital period 1–1000 days. Among them the H emission is detected in 13 stars with various intensity. The results of this inspection are presented. When combined with the previous data, our results show that the Be-star frequency in spectroscopic binaries along the orbital periods exhibits a sharp maximum in the period range 100–300 days, and that the stars of strong H emission concentrate in the same period range.     

Retrieval and tentative indentification of the 3 μm spectral feature in Titan's haze

Recently, an unidentified 3.3-3.4 μm feature found in the solar occultation spectra of the atmosphere of Titan observed by Cassini/VIMS was tentatively attributed to the C-H stretching mode of aliphatic hydrocarbon chains attached to large organic molecules, but without properly extracting the feature from adjacent influences of strong CH₄ and weak C₂H₆ absorptions (Bellucci et al., 2009). In this work, we retrieve the detailed spectral feature using a radiative transfer program including absorption and fluorescent emission of both molecules, as well as absorption and scattering by haze particles. The spectral features of the haze retrieved from the VIMS data at various altitudes are similar to each other, indicating relatively uniform spectral properties of the haze with altitude. However, slight deviations observed near 127 km and above 300 km suggest inhomogeneity at these altitudes. We find that the positions of the major spectral peaks occur at 3.33-3.37 μm, which are somewhat different from the typical 3.3 μm aromatic or 3.4 μm aliphatic C-H stretches usually seen in the spectra of dust particles of the interstellar medium and comets. The peaks, however, coincide with those of the solid state spectra of C₂H₆, CH₄, and CH₃CN; and a broad shoulder from 3.37 to 3.50 μm coincides with those of C₅H₁₂ and C₆H₁₂ as well as those of typical aliphatic C-H stretches. This result combined with high-altitude (∼1000 km) haze formation process recently reported by Waite et al. (2007) opens a new question on the chemical composition of the haze particles. We discuss the possibility that the 3 μm feature may be due to the solid state absorption bands of these molecules (or some other molecules) and we advocate additional laboratory measurements for the ices of hydrocarbon and nitrogen-bearing molecules present in Titan's atmosphere for the identification of this 3 μm feature.     

Mineral grains and the 10 and 20 μm spectral features in the Trapezium nebula

The infrared emission observed for dust in the Trapezium nebula over the waveband 8–40 m cannot be explained on the basis of a simple silicate model involving either terrestrial or lunar silicates. Laboratory measurements were carried out to determine the opacity coefficient of finely crushed Murchison meteorite material. Murchison material (including organics within it) provides a better fit to the Trapezium data than any known silicate, but the agreement is inferior to that obtained for a diatom model.     

Contamination of the 5394 Å spectral region by telluric lines

The spectral region in the vicinity of 5394 Å contains three prominent photospheric spectral lines, which can be used as a solar plasma diagnostic tool. The occurrence of telluric lines in this region is a potential source of systematic and random errors in these solar spectral lines. The goal of our investigation was to determine the telluric line contamination of this interesting spectral region. Several series of high-resolution solar spectra within an interval of about 4 Å around the 5394 Å wavelength were observed at different zenith distances of the Sun. Comparison of these spectra has permitted identification of telluric lines in this spectral interval. The observations were carried out with the horizontal solar spectrograph of the Heliophysical Observatory in Debrecen. Telluric feature blending was identified in the blue and red wings of the Fe I 5393.2 Å line, and in the local continuum of the Mn I 5394.7 Å line. The blue wing of the Fe I 5395.2 Å line is contaminated by a weak telluric feature too. The red continuum of this line has a more prominent telluric contamination. A dozen of water vapor telluric lines that determined the observed telluric features were identified in this spectral interval. The profiles of three telluric lines that have a significant influence on both the profiles of solar spectral lines and the level of local continuum were derived, and the variation of their parameters (equivalent width and central depth) with air mass were analyzed.     

Rapid spectral variability of ɛ PerA

The results of high-resolution spectropolari metric observations (R = 60 000) of the B0.5-type subgiant ? PerA are reported. Regular components of line profile variations with the frequencies 3.82–12.99 d^?1 are found. A possible relation between the non-radial pulsations of the star and the observed regular variations of the line profiles is shown. A wavelet analysis of the difference of line profiles in the spectrum of ? PerA is performed. The amplitude of the wavelet spectrum is found to have two maxima at 10–20 and 50–60 km/s velocity scales. It is suggested that the first maxi mum corresponds to the amplitude of fluctuations in the velocity field of large-scale motions in the non-radially pulsating photosphere of the star, whereas the second maximum is associated with the variation of the half widths of spectral line profiles. An upper limit for the effective magnetic field of the star is inferred.     

Spectral observations using a BTA telescope of chemically peculiar stars in the spectral region near the Li I (6708 Å) resonance doublet

New spectral observations of chemically peculiar (CP) magnetic stars were obtained using an NES echelle spectrometer with a BTA telescope in the Special Astrophysical Observatory (Russian Academy of Sciences). Several stars were shown to have anomalous Li abundances. Testing and monitoring the stars with Doppler shifts Vsini > 10 km/s indicated that the lithium 6708 Å line was variable in the spectra of some roaAP-CP stars. To distinguish variable features in the spectra, the dispersogram technique was used. The most peculiar among the stars studied is HD 12098. The strong and variable lithium 6708 Å line was detected in the spectrum of this star. The star has been shown to have greatly different lithium abundances in two rotation phases corresponding to opposite surface areas. As mentioned earlier, a similar behavior of the Li blend was found in the spectra of HD 83368 and HD 60435 which have lithium spots on their surface. Spectral observations of slowly rotating CP stars with the Doppler shifts Vsini < 10 km/s revealed the strong and nonvariable lithium 6708 Å line in the spectra of these stars. Quantitative spectral analysis using the Li I 6708 Å resonance doublet and the Li I 6103 Å line shows the lithium abundance, as determined by the 6103 Å line, to be somewhat greater than that determined by the 6708 Å line. A higher ratio of ⁶Li/⁷Li amounting to ～0.3–0.5 was found in these stars. ⁶Li production is assumed to be due to spallation reactions on the surface of magnetic CP stars; this isotope ratio remained in strong magnetic fields.     

Peculiarities of the variations in the coordinates of the Earth’s pole

The appearance of features with cusp points on the diagrams of changes in the coordinates of the Earth’s instantaneous pole (polhodes) is considered as the result of mapping onto the plane of its displacement over the surface during the Earth’s rotational-translational motion. The results of qualitative and quantitative analyses of the data on the coordinates of the Earth’s instantaneous pole are discussed. The basic principles of the theory of Whitney singularities and their application for explaining the bifurcations of the equilibrium positions for the Zeeman catastrophe machine (Arnold 1990) are used in the analyses.     

Studying the errors in the estimation of the variation of energy by the “patched-conics” model in the three-dimensional swing-by

The swing-by maneuver is a technique used to change the energy of a spacecraft by using a close approach in a celestial body. This procedure was used many times in real missions. Usually, the first approach to design this type of mission is based on the “patched-conics” model, which splits the maneuver into three “two-body dynamics.” This approach causes an error in the estimation of the energy variations, which depends on the geometry of the maneuver and the system of primaries considered. Therefore, the goal of the present paper is to study the errors caused by this approximation. The comparison of the results are made with the trajectories obtained using the more realistic restricted three-body problem, assumed here to be the “real values” for the maneuver. The results shown here describe the effects of each parameter involved in the swing-by. Some examples using bodies in the solar system are used in this part of the paper. The study is then generalized to cover different mass parameters, and its influence is analyzed to give an idea of the amount of the error expected for a given system of primaries. The results presented here may help in estimating errors in the preliminary mission analysis using the “patched-conics” approach.     

Dynamics of Hα spicules according to spectral observations at various heights of the solar chromosphere

Almost simultaneous height sequences of 69 spicules in the Hα line have been studied. The spectra are obtained at six heights during 6 s on the east side of the solar disk with the 53-cm Lyot coronagraph of Abastumani Astrophysical Observatory. Radial velocities V _r, total intensities or equivalent widths W, full widths at half maximum of intensity (FWHM) at all heights are determined (about 300 profiles of the Hα line). It is found that:

1. Absolute values of radial velocities increase linearly with the height (see Equation (1));
2. variation of the sign of the radial velocity along single spicules was never observed.

These results combined with the findings on the spicules radial velocities and shifts obtained earlier (Kulidzanishvili and Nikolsky, 1978; Nikolsky and Platova, 1970) led us to the conclusion that the 5-min tangential oscillations of spicules involve the entire spicule at once. The intensity height scales for single spicules and for the chromosphere ‘in toto’ are determined; they turned out to be 2.5 × 10³ km and 1.9 × 10³ km respectively (see Equations (2) and (3)). The dependence curve of the Hα line half-widths Δλ on the height h is drawn. The Hα line half-width for those spicule groups which are traced at all heights (10 spicules) decreases with the height (Figure 4); for the majority (～60 spicules) it remains essentially constant. Non-thermal ‘turbulent’ velocities V _t, in Hα spicules are defined. A mean value of the ‘turbulent’ velocity V _t at T = 6000° appeared to be 20–30km s^?1. The hydrogen concentration in the spicules at 5000 km is 6 × 10¹¹ cm^?3.     

High spectral resolution ground-based observations of Venus in the 450- to 1250-cm−1 region

Ground-based observations of Venus were made with a 5-cm drive Michelson interferometer during December 1970 and December 1973. The thermal emission spectrum of the central portion of the apparent disk was recorded from 450–1250 cm^?1 with an apodized spectral resolution of 0.25 cm^?1. All statistically significant sharp line absorption features in the spectrum have been identified with gaseous CO₂. Comparison between the observed spectrum and a synthetic spectrum computed from a model atmosphere, assuming gaseous CO₂ and a sulfuric acid haze as opacity sources, indicates good agreement. A broad diffuse absorption feature associated with the sulfuric acid haze is evident in the 870- to 930 cm^?1 region. With the exception of the rotational lines of the 927-cm^?1 CO₂ band, the above feature appears as a continuum down to 0.25 cm^?1 resolution. In the 750- to 1250-cm^?1 range, the spectrum exhibits moderate thermal contrast with maximum brightness temperatures of 234–238°K occurring near 825 cm^?1. These temperatures are in general agreement with previous measurements.     

Spectrophotometric variability of the magnetic CP star 56 Arietis in spectral region from 1950 to 3200 Å

We presented a phenomenological mode that attributes the precession of perihelion of planets to the relativistic correction. This modifies Newton’s equation by adding an inversely cube term with distance. The total energy of the new system is found to be the same as the Newtonian one. Moreover, we have deduced the deflection of light formula from Rutherford scattering. The relativistic term can be accounted for quantum correction of the gravitational potential and/or self energy of objects.     

The relationship between the radio core-dominance parameter and spectral index in different classes of extragalactic radio sources(Ⅲ)

Active galactic nuclei(AGNs) can be divided into two major classes,namely radio-loud and radio-quiet AGNs.A small subset of the radio-loud AGNs is called blazars,which are believed to be unified with Fanaroff-Riley type Ⅰ and type Ⅱ(FRIⅡ) radio galaxies.Following our previous work,we present a latest sample of 966 sources with measured radio flux densities of the core and extended components.The sample includes 83 BL Lacs,473 flat spectrum radio quasars,101 Seyferts,245 galaxies,52 FRIsⅡs and12 unidentified sources.We then calculate the radio core-dominance parameters and spectral indices and study their relationship.Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources.We also confirm that the correlation between core-dominance parameter and radio spectral index extends over all the sources in a large sample presented.     

The relationship between the radio core-dominance parameter and spectral index in different classes of extragalactic radio sources(Ⅱ)

Active galactic nuclei(AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which are believed to be unified with Fanaroff-Riley type Ⅰ/Ⅱ(FRI/Ⅱ) radio galaxies. Following our previous work(Fan et al.), we present a sample of 2400 sources with measured radio flux densities of the core and extended components. The sample contains 250 BL Lacs, 520 quasars, 175 Seyferts, 1178 galaxies, 153 FRI or FRⅡ galaxies and 104 unidentified sources. We then calculate the radio core-dominance parameters and spectral indices, and study their relationship. Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources. We also confirm that the correlation between core-dominance parameter and spectral index exists for a large sample presented in this work.