Fine structure in the inner corona observed at the 1970 eclipse

On the slit spectrogram obtained at the 1970 eclipse in Mexico, the intensities of four coronal lines (Nixiii 5116, Fexiv 5303, Fex 6374, and Nixv 6702) and the continuum were measured as a function of distance along the slit. It is found that there exist a lot of fine fluctuations both in the lines and in the continuum intensities superposed on a large scale formation. The correspondence of such fluctuations between the continuum and the lines is good, with the exception of the line 6374 which shows a peculiar fluctuation. It is shown that the intensities of the three lines 5116, 5303, and 6702 seem to be proportional to the square of the continuum intensity while the 6374 line intensity may be proportional to the fourth power or more.     

A coronal condensation observed at the total solar eclipse of June 11, 1983 and a related transient prominence

A coronal condensation was observed simultaneously with Fexiv 5303, Fex 6374, Fe xi 7892, and H filtergraphs. The size and shape of the condensation in 5303 are different from those in other filtergrams. H filtergrams taken around the eclipse time show that a small transient prominence exists in close proximity to the condensation core and behaves like a post-flare loop system, though the appearance is quite different and no flare-report exists. A small-scale energetic phenomenon seems to have occurred at the top of magnetic loops.Contributions from the Kwasan and Hida Observatories, University of Kyoto, No. 285.     

CORONAL RADIATION AND HELIUM λ584 EMISSION IN ACTIVE REGIONS

Based on EUV observations of eleven sunspot regions obtained with the Coronal Diagnostic Spectrometer, CDS, on SOHO we have studied the spatial distribution, temporal variation and wavelength shift of the Hei 584 line. We find a relatively high spatial correlation between the coronal line Fexvi 360 and the Hei 584 line. This points to coronal back-radiation as an important contributor to the formation of the Hei line in active regions. However, contribution to the line formation from another source is suggested by the following two findings: First, the red-shifted line profiles of both Hei 584 and the transition region lines tend to be more intense than blue-shifted profiles. Second, the Hei 584 emission changes significantly faster than the coronal line emission.     

The behaviour of the infrared lines of neutral oxygen and the balmer lines of hydrogen in the spectra of early-type stars with emission lines

The equivalent widths of the oxygen lines at 7774 and 8446 and of H (and some H) have been measured for 22 early-type, emission-line stars. A strong correlation between H and 8446 intensities has been found, although there is no such correlation between H and 7774. This confirms the probability that Bowen's mechanism is operative (the neutral oxygen 3³ D state is overpopulated because the excitation energy of Ly- nearly coincides with that of theOi 1025 line). The possibility of using 8446 and H equivalent widths for a comparison of oxygen to hydrogen abundances in these stars is discussed.     

The observed limb effect in Fraunhofer lines,I

The absolute limb effect is presented for Fei lines 3767 and 3969; for five Tii lines of multiplet 42 near 4535 and one Tiii line at 4534; two lines of Mgi, 4571 and 5172; two lines of Baii at 5854 and 6497. The scattered light of the McMath solar telescope is illustrated by several figures but not applied to the limb-effect observations. It is suggested that the supergravity shift at the limb is the result of scattering of the atoms in anisotropic velocity field.Operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.     

The polarization of coronal emission lines

By means of a photographic polarimeter, we attempted to measure both the amount and direction of linear polarization of all emission lines between 3400 and 9000 Å in the inner corona (1.034 r/r ₀ 1.085). Only the green and red coronal lines have been analyzed in detail. Neither of these lines shows polarization exceeding the probable error of 1.0% for 5303 and 1.8% for 6374. None of the other 17 coronal lines observed during the 7 March, 1970 solar eclipse show any obvious (>5%) polarization.Presently at the Sacramento Peak Observatory.     

Physical conditions in NGC 6164-5

From spectroscopic observations of the emission lines H, 4959 and 5007[Oiii], H, 6584[Nii], 6717 and 6731[Sii] and some interferometric data in H and [Nii] it was established that NGC 6164 and NGC 6165 have characteristics of normal Hii regions for Ne and Te. They are embedded in a very tenuous medium nearly coincident with the Strömgren sphere of the central star HD 148937, corresponding to the outer peripheral structure described by Westerlund. Variations of the relative abundances of N, O, and S are discussed.     

On the Correlation Between the he ii λ304 Network Brightening and the Photospheric Magnetic Field

Near simultaneous coronal EUV images were used to show that the He ii 304 network brightening is independent of coronal EUV radiation. We studied the quantitative relation between the intensity of He ii 304 network brightening with the associated magnetic elements. An almost linear relationship was found between the He ii 304 network brightening and the magnetic field for a field strength higher than 10 G with exceptions at neutral lines and in the intra-network. We also calculated the most probable formation height of He ii 304 network elements using the potential extrapolation of the photospheric magnetic field. The results show that He ii 304 network elements form at or around 3000 km above the height of the layer at which the sources of magnetic flux are deployed.     

The high-dispersion continuous ultraviolet solar spectrum and the Balmer-jump

Among the intensities, determined at about 200 wavelengths between 3000 and 4100 Å in the spectrum of the centre of the sun's disk (Houtgast, 1965), the 32 highest ones (windows) were plotted and compared with absolute intensities given by other authors.The intensities in between the Fraunhofer lines from 3600 to 4000 Å, as determined here for the first time with high dispersion, reveal a detailed picture of several absorption features, one of which can be attributed to a Balmer jump of 0.03, a value in accordance with that found for stars and in agreement with the strengths of the high Balmer lines.The much higher value of the Balmer jump for the sun, as quoted in literature, in reality refers to the total intensity jump between 4000 and 3600 Å, which is mainly due to the crowding of Fraunhofer lines.     

A new type of a photoelectric magnetograph

The electro-optic deflector as an analyzer of circular polarization in the photoelectric magnetograph is described. The electro-optic deflector consists of an electro-optic crystal and a polarizing beamsplitter. The plane bifurcation of this beamsplitter coincides with the spectrograph dispersion direction. The beamsplitter bifurcates a spectral line in two components. The distance between them is ₀. The photometer slit is situated between these components. Both components of Zeeman splitting fall on the photometer slit but the distance between them varies from ₀ + 2 _H to ₀ – 2 _H (where _H is the Zeeman splitting) with the electric voltage frequency applied to the electro-optic crystal. The intensity variations at the photometer slit are proportional to 4 _H .     

The observed limb effect in Fraunhofer lines,II

In this paper the absolute limb effect for a number of Fraunhofer lines observed at the McMath Solar Observatory is given. Results, uncorrected for scattered light, are given for the following lines: Fei 37334.9, 3735.3, 5123.7, 5250.2, 5434.5, 6678.0, and 8886.6. Additional lines observed are five lines of CN 3876.3–3880.0, two lines of Cai 6161.3 and 6162.2, one line of Nai, 6160.7, and one CN line (7957.0) of the red system.Operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.     

Area variation with temperature of supergranule network features in the solar transition zone

Areas of network emission features in C ii 1135, C iii 977, O iv 544 and O vi 1032 were measured in and out of coronal holes. In the quiet Sun these areas, on the average, showed a 20% increase between C ii and O vi. In the coronal holes there was no significant average variation, but a number of the features showed an interesting decrease in area at intermediate temperatures.     

F07164+5301: an ESB source with WR features

We report on a new ESB source, as defined by Allenet al. (1991), with Wolf-Rayet (WR) bands in its optical spectrum. The WR bump at 4605-4686 is detected. The bump consists of broad HeII 4686, NV4605-4619, NIII4634-41, and possibly, CIII4647-52 emission. The narrow nebular lines are clearly discernable on our spectrum. The number of WR stars derived from the luminosity of HeII4686 is about 8100. The oxygen abundance is about 9.06×10^–4, greater than the solar value.     

Potential models of the unipolar sunspot magnetic field

The potential models of the unipolar sunspot magnetic field are calculated on the basis of magnetographic measurements of the magnetic field made in the three spectral lines of different intensities, H, Cai 6103 and Fei 4808. The computed distributions of the magnetic field vector are compared with actual distributions observed at these three levels. It is shown that the electric current density in the spot reaches values up to 10⁵ CGSE in the volume contained between formation depths of two pairs of lines, Fei 4808-Cai 6103 and Fei 4808 - H. Therefore, the magnetic field of the spot deviates strongly from a potential configuration. To the contrary, at higher levels, in the semi-infinite volume restricted at the bottom by the hydrogen H-line, the field appears to be quite close to a potential one.     

Scanner observations of the Be starsν Gem,κ Ori,β Mon andω CMa

The photoelectric spectrophotometric scans of the Be stars Gem, Ori, Mon and CMa have been analyzed to find out few stellar parameters. The absolute energy distributions of these stars in the wavelength range 350–750 nm have been given. Their effective temperatures and gravities have been estimated from comparisons with non-LTE model atmospheres. The stars Gem and Mon have been found to have Balmer discontinuities in emission. The excess emission in the region 620–750 nm has been observed for Mon and CMa. The evolutionary aspects of these stars are discussed and their masses have been estimated.     

Spectrophotometry of Comet Bradfield (1980t) during post-perihelion period

Spectrum scans of the head of Comet Bradfield (1980t) covering the wavelength range 365–640 nm were made on two nights when the heliocentric distance of the comet varied from 0.55 to 0.58 AU. The emission features of the CN band at 388 nm and Swan band sequence of C₂ at 474 nm, 516 nm, and 563 nm are identified and absolute fluxes in these bands as well as in the continuum are derived. The continuum energy distribution curves of the comet have been compared with those of the Sun and the star Crv (G5 III). An estimate of the number of C₂ and CN molecules in the head of the comet has been made through the measured intensities of their respective bands lying in this region.     

Coronal He+ λ304 radiation

The intensity of the He⁺ 304 coronal line relative to the H⁰ 1216 line, including the dominant contribution due to resonance scattering, is presented. All physical processes important in the corona are included. It is found that He⁺ 304 is a major contributor to the XUV corona, and that the sensitivity of the He⁺ 304/H⁰ 1216 intensity ratio to coronal temperature is very weak, supporting the belief that this ratio is a good indicator of the coronal helium abundance.     

Scanner observations of comet P/Crommelin 18181

Spectral scans of the coma of comet P/Crommelin 1818. I have been obtained in the wavelength range 3200–6500 Å. Strong emission features of CN(3883 Å) and C₂ Swan bands (4695, 5165, and 5538 Å) have been identified. Some weak emission features of CH(3890 Å), C₃(4050 Å), CN(4200 »), and C₂ + CH(4358 ») were also detected. Sodium was found to be absent in this comet. An estimate of CN and C₂ abundances has been made and their production rate have been derived.     

Correlations between statistical population indices and spectral characteristics of carbon stars

The coefficients of correlation between spectroscopic data published by Yamashita (1967) and others for carbon stars and the statistical population indices calculated for these stars at the Toru Observatory are calculated (Table II). The intensity estimates of Cai 4227 Å, Nai D lines, the C¹³/C¹² ratio, then=n(Li/Ca) index, as well as CN and probably C₂ bands are higher in population I carbon stars. The CH(G) band and probably hydrogen (H, H, H) lines as well as Baii 4554 and 4934 Å lines are stronger in population II carbon stars. The photoelectric colour indices, corrected for interstellar reddening do not show significant population effects. They can be used as spectral type equivalents. For a population criterion the CH/CN intensity ratio is proposed.     

Narrow band CCD imagery of southern galaxies in strong lines and continua: NGC 613

CCD narrow band imagery of the southern barred spiral NGC 613 has been obtained in the light of H, H, [Oiii] 5007 Å, [Oii] (3726+29) Å and continua at 3765, 5230, and 6500 Å. Absolute fluxes have been obtained for the lines H and [Oiii] 5007 Å and continua at 5230 and 6500 Å. Distribution of ages, monochromatic colour vs absolute brightness and [Oiii]/H are discussed.