The ultraviolet absorption band at 2175 Å: Correlations with other interstellar features

The hump in the ultraviolet part of the interstellar extinction curve is interpreted as a broad diffuse absorption band. Its equivalent width is estimated for 36 stars by means of OAO-2 data. The equivalent widths are correlated with the following parameters: colour excessE(B-V), colour excessE(B – V), depth of the band m _max, equivalent widths of the diffuse bands at 5780 and 6284 Å, and the column density of neutral hydrogenN _HI. The physical parameters half-width and oscillator strength of the band at 2175 Å are estimated.     

Ultra-violet nightglow spectrum from 1900 Å to 3400 Å

Two spectra of the ultra-violet nightglow from 1900 Å to 3400 Å have been recorded by a fast wide-field spectrograph during balloon flights from Aire sur Adour, France on 15 September, 1969 and on 5 October, 1970. These two spectra are composed of theOi line at 2972 Å, of the molecular oxygen Herzberg band systemA ³ _u ⁺ X ³ _g ^– and of a molecular band system that seems to belong to the NO SystemX ² C ² X ⁺, situated at 1991 ű4 Å, 2060 ű4 Å and 2136 ű4 Å. Around 2540 Å, there is absorption by ozone at the altitudes at which the spectra were recorded (35 km and 40 km). We present our calculated value of ozone absorption at 35 km, and the zenith-horizon variation of the nightglow emission.     

A new microwave/X-ray diagnostic for the thermal phase of solar flares

We have observed 10 solar bursts during the thermal phase using the Haystack radio telescope at 22 GHz. We show that these high frequency flux observations, when compared with soft X-ray band fluxes, give useful information about the temperature profile in the flare loops. The microwave and X-ray band fluxes provide determinations of the maximum loop temperature, the total emission measure, and the index of the differential emission measure (q(T)/T = cT^–1). The special case of an isothermal loop ( = ) has been considered previously by Thomas et al. (1985), and we confirm their diagnostic calculations for the GOES X-ray bands, but find that the flare loops we observed departed significantly from the isothermal regime. Our results ( = 1–3.5) imply that, during the late phases of flares, condensation cooling ( 3.5) competes with radiative cooling ( 1.5). Further, our results appear to be in good agreement with previous deductions from XUV rocket spectra ( 2–3).     

Spectroscopic observations of delta orionis

The H profile in the spectrum of Orionis shows phase-dependent changes, with a period of variation equal to the orbital period fo the binary system. The profile shape changes from a normal absorption profile at zero phase to a P Cygni-type at a later phase, to an absorption profile having emission at the centre of the profile, to a normal absorption profile at the end of the period. The spectra have been obtained at the Cassegrain focus of Kavalur Observatory telescopes (50 and 100 cm) at 17.2 Å mm^–1 reciprocal dispersion and resolution 0.3 Å at 6562.817 Å. Assuming that the P Cygni profile is formed by a spherically-symmetrical region, the analysis gives a shell radius of 2.18 stellar radius and an electron density in the shell equal to 6.54×10^–9 cm^–3, with the observed expansion velocity of 50 km/s^–1, a mass loss of 1.3×10^–7 M per year.An analysis has been carried on the radial velocity data of earlier observers and the present radial velocity data. It is found that the orbital elements change. The presence of apsidal motion is confirmed by the increasing value of . The radial velocity of the centre of mass, , shows periodic variation. These observations confirm the presence of a third body. The values ofK (mean amplitude),P (period),a sini, and mass functionf(m), indicate a regular decrease, thereby confirming the mass transfer/mass loss from the system.     

The expansion of negative powers of the mutual distance between two planets

An outline of a new method is given to obtain the expansion of ^–S by the method of W. M. Smart, using Taylor theorem and neglecting powers higher than the fourth in the eccentricity and inclination.     

Properties of the λ2200 Å interstellar absorber

A strong correlation between the equivalent widths of the 2200 Å absorption band in the interstellar extinction curves and the colour excessesE _B-V of the stars was found. The oscillator strength and the damping constant of the 2200 Å transition were estimated. From these findings some conclusions concerning the identification problem were drawn.     

Decametric survey of discrete sources in the northern sky

The region of the celestial sphere between declinations =52°.3 and =59° and right ascensions =1^h and =19^h has been surveyed with the UTR-2 radiotelescope. The results of the survey are presented.The catalogue contains the positions and flux densities of 313 radio-sources detected at 10, 12.6, 14.7, 16.7, 20, and 25 MHz.     

On the nature of interstellar grains

Data on interstellar extinction are interpreted to imply an identification of interstellar grains with naturally freeze-dried bacteria and algae. The total mass of such bacterial and algal cells in the galaxy is enormous, 10⁴⁰ g. The identification is based on Mie scattering calculations for an experimentally determined size distribution of bacteria. Agreement between our model calculations and astronomical data is remarkably precise over the wavelength intervals µ^–1 < ;^–2 < 1.94µ^–1 and 2.5µ^–1 < ;^–1 < 3.0 ;^–1. Over the more restricted waveband 4000–5000 Å an excess interstellar absorption is found which is in uncannily close agreement with the absorption properties of phytoplankton pigments. The strongest of the diffuse interstellar bands are provisionally assingned to carotenoid-chlorophyll pigment complexes such as exist in algae and pigmented bacteria. The 2200 Å interstellar absorption feature could be due to degraded cellulose strands which form spherical graphitic particles, but could equally well be due to protein-lipid-nucleic acid complexes in bacteria and viruses. Interstellar extinction at wavelengths <1800 Å could be due to scattering by virus particles.     

Identification of lines in the spectrum of the quasar 0237–233

The emission and absorption lines (3716–4290) in the spectrum of the quasar 0237–233 are identified within the framework of the PLS model. The available evidence indicates that it is a helium star. Similarities between the spectral properties of 0237–233 and the star Upsilon Sagittarii are pointed out. Predictions are made for the absorption-line spectrum which falls outside 3716–4290 and also for an expected discontinuity at 2600.     

Delta-sunspots and X-class flares

All-sunspots from September 1986 to December 1992 in solar cycle 22 are used to investigate the characteristics of-sunspots and the relationship between-sunspots and X-class X-ray flares. The main results of this statistical study are as follows.

Expansion of the planetary mutual distance raised to any negative power by the method of symbolic differential operators

We present a literal approach to evaluate ^–s necessary for the construction of high order planetary theories. This approach is valid to be applied on very large scale digital computers with standard Poisson series programs, for high order and high degree planetary theories. We apply the method of symbolic differential operators for single variable functions, and the binomial theorem expansions, for the evaluation of ^–s . We utilize Laplace coefficients and its derivatives to carry out the development, without dealing with Newcomb operators or Hansen's coefficients.     

Grain size dependence of far-infrared extinction spectra of amorphous fine grains

The far-infrared extinction spectra of fused silica grains with the size range from 1.8 m to 60 Å were measured. The spectra depend clearly on the grain size. For large grain sizes (from 1.8 m to 400 Å) the spectra show almost the ^–2 dependence ( is the wavelength), which resembles that of the bulk material. For fine grains (70 and 60 Å) the spectra are less steep, the wavelength dependence being ^–1. This grain size dependence of extinction spectra agrees essentially with the prediction of Seki and Yamamoto.     

24MgH+ in the solar photospheric spectrum

The²⁴MgH⁺ (A ¹⁺ –X ¹⁺) molecular lines have been identified in the photospheric spectrum. The rotational excitation temperature determined from the analysis of molecular line intensities of²⁴MgH⁺ is found to be of the order of 4850 K which corresponds to the photospheric temperature of the Sun. The CNDO/2 dipole moments of²⁴MgH⁺ for internuclear distance range: (1.3–2.1) Å in theX ¹⁺ state can be approximated byM(R)=4.92+1.33R. Estimations for the spontaneous emission Einstein coefficients (A _{v v} ) and the absorption oscillator strengths (f _{v v} ) for the (1, 0), (2, 0), and (2, 1) transitions in theX ¹⁺ state of the²⁴MgH⁺ ion are also made.Work partially supported by the CNPq, Brasilia under contract number 30.4076/77.     

Possible presence of magnetic fields and iron content of atmospheres of “Metallic” Am-stars

Measurements with a CCD camera were made of two Fell lines at =6747.7 Å and 6149.2 Å in the spectra of 12 Am stars. The greater line strength of Fell 6147.7 Å relative to that of 6149.2 Å can be taken as evidence of a magnetic field in the atmosphere of the classical Am-star 15 Vul. Our observations support the conclusion of Mathys and Lanz [1] that a magnetic field is present in the atmosphere of yet another Am star, o Peg. For the rest of the stars studied the differences in the equivalent widths of the Fell lines can be explained by blending of the Fell line 6147.7 Å. Using the Fell line 6149.2 Å, which is free of blending, we estimate the iron content of the atmospheres of 12 Am stars with effective temperatures ranging from 7400 K to 9800 K. Our results indicate a star-to-star variation in log (Fe) of no less than 0.5 dex, a value greater than the measurement accuracy.Translated from Astrofizika, Vol. 37, No. 2, pp. 187–195, April–June, 1994.     

A spectrophotometric study of GG cassiopeiae

The continuum energy distributions of a totally eclipsing binary system GG Cas at phases 0 _. ^P 903 and 0 _. ^P 003 in the wavelenght range 3200–7600 Å have been presented and discussed. The flux of continuum of the secondary star seems to dominate longward of 4500 Å. The spectral types of the systemic components are found to be as B4+K0.     

Search for the matter clumps in scalesZ ~ 1

The diagramV - log(1 +z _e ) as function of (, ) is considered for the quasars. HereV is the apparent visual magnitude,z _e is the emission line redshift, and are the equatorial coordinates. Two opposite extreme spots NE and SE are observed on the sky, where the inclination of the straight line fitting the dependenceV - log(1 +z _e ) is maximum and minimum. The coordinates of the centres of these extreme spots are ( _NE, _NE) = (282°, +42°) and ( _SE, _SE) = (70°, -38°) with errors 5°. A hypothesis of the Superattractor (SA) is proposed to explain such an effect. Two independent tests of this hypothesis are realized. First, the dependence or the frequency a of the absorbers in QSO spectra on (, ) is investigated. A region of the larger a is found. The coordinates of its centre are (, ) = (82°, - 10°) with error 5°. Second, the cases ofz _a >z _e are plotted in the Mercatorial projection (, ). The most of the casesz -z _e > 0.02 are concentrated within the circle with radiusR = 34° and centre (, ) = (50°, - 15°). The both anomalous regions overlap the Southern extreme spot around SE. The SA direction is (, ) = (67°, -21°) with errors about 12°. The redshift of SA isz _SA = 1.7 ± 0.3 that corresponds to the distancer _SA = (3100 ± 300)h ^–1 Mpc for the Hubble constantH ₀ = 75h kms^–1 Mpc^–1. The SA mass isM _SA ~ 10¹⁸-10²⁰ M . The orientation of the normal to the quasiperiodical large-scale sheet structure on the sky occurs near SA.     

Spectroscopy of Solar Prominences Simultaneously From Space and Ground

We present a comprehensive set of spectral data from two quiescent solar prominences observed in parallel from space and ground: with the VTT, simultaneous two-dimensional imaging of H4862 Å and Caii 8542 Å yields a constant ratio, indicating small spatial pressure variations over the prominence. With the Gregory, simultaneous spectra of Caii 8542 Å and Hei 10830 Å were taken, their widths yielding 8000 K <T _kin<9000 K and 3<v _nth<8 km s^–1. The integrated line intensities show a distinct relation E(Hei) versus E(Caii) for each prominence (`branching'). The intensity ratio of the helium triplet components is used for a simple estimate of the optical thickness, which is <1.0 for the fainter prominence but reaches up to =2.0 for the brighter one. The <sub>0</sub> values allow us to deduce the source function from the central line intensities and thus a mean excitation temperature T<sub>ex</sub> <sup>mean</sup>=3750 K, which determines the relative populations of the helium <sup>3</sup> S and <sup>3</sup> P levels. With SUMER, we sequentially observed six spectral windows containing higher Lyman lines, `cool' emission lines from neutrals and singly charged atoms, as well as `hot' emission lines from ions like Oiv, Sv, Nv, Ov, and Svi. The spatial variation of the EUV lines along the SUMER slit shows a pronounced maximum at the main prominence body and `side-regions' where the `hot' lines are significantly enhanced with respect to the `cool' lines from neutral and singly-ionized atoms. These selected locations were averaged over 7 and the resulting mean EUV lines were fitted by Gaussians yielding realistic widths and integrated line intensities. The intensities of `hot' lines blue-wards of the Lyman series limit appear reduced in the main prominence body but enhanced in the `side-regions'. This absorption is also visible in TRACE images of Feix/x171 Å as fine dark structure which covers only parts of the main (`cool') prominence body. The Lyman lines show a smooth decrease of both line widths and integrated emission, with increasing upper level k=5 to k=19; the widths are smaller for the prominence that yields lower T <sub>kin</sub> from the ground-based spectra. The level populations along the line of sight follow for 5 lek le a smooth Boltzmann distribution with T <sub>ex</sub>>6×10<sup>4</sup> K, the levels k>8 appearing more and more overpopulated. The larger widths of the Lyman lines require high non-thermal broadening close to that of `hot' EUV lines. In contrast, the Heii emission is more related to the `cool' lines.     

Disc system delta Capricorni

FirstUBV photoelectric photometry of the eclipsing binary system Cap has been presented. An improved period of 1^d.022766 has been given. The duration of primary eclipse comes out to be more than double the duration given earlier. The depth has also been found to have increased. The light changes during eclipses show slight asymmetry. Eccentricity appears to be present in the system. Light and colour curves show variations. Primary component appears to be surrounded by a disc, the size of which is comparable to the size of the primary component. Two dips are seen around phases 0.20 and 0.67, the first appears more definitive, and is attributed to the wave-like distortion, like the one found in RS CVn binaries. The discussion reveals that Cap is a very complicated system.     

High dispersion spectroscopic study of quiescent prominences

The utility of very high dispersion spectra (5–11 mm/Å) for the study of line profile and velocity structure in quiescent prominences is demonstrated by observations, taken with the spectregraphic slit positioned normal to the limb in H 6563 Å, He D₃ 5876 Å, and Ca⁺K 3933 Å. The emission profiles of both H and the K line often show a central reversal (absorption). Emission structures in the K-line can be complex with details as narrow as 0.04 Å. Frequently this structure consists of two distinct components: a central, strong, rather narrow line, and an often displaced, weak feature of undefined profile appearing as fuzz. It is suggested that this fuzz indicates an exchange of matter between the prominence and the corona.Visiting Astronomer, Institute for Theoretical Astrophysics, Oslo, Norway.Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.     

Does Einstein's relationE=mc 2arise from the metric?

In this Letter we propose to consider the four-energy-space whose coordinates are composed as follows: (i) the coordinate ⁰ refers to the internal energy of the body (it is involved as an unknown function of the rest-energy and the kinetic energy of the body), and (ii) the coordinates ¹, ², ³ relate to the presence of gravitational, electromagnetic, and thermal energy at the location of the body respectively. We involve yet the proper energy interval d² by analogy to the four-interval ds ² in general relativity. From such metric field we calculate the Ricci tensor in the simplest case. In addition, we require its form to be the same one as that considered by Schwarzschild. Comparing both solutions we obtain Einstein's relationE=mc ².