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1.
We have examined seven active regions of the Skylab period in the EUV (Harvard College Observatory), and in H and K3 (Observatoire de Meudon, spectroheliograms and patrols) in order to elucidate the magnetic geometry in the coronal environment of filaments. We have also looked for signatures of magnetic reconfigurations associated with instabilities (i.e. velocities or disappearances) of filaments. Out of sixteen H filaments observed, six were stable (lifetime 48h). All the filaments lay within coronal cavities as seen in lines formed above 1.5 × 106 K (Mgx
625, Sixii
521, Fexvi
417, Fexv
361). None of the stable filaments had arcades or arches spanning the cavities except (sometimes) at the ends of the filaments. On the other hand, most (8/10) of the unstable filaments (having concurrent Doppler shifts or a subsequent DB within 24h) had arcades or single arches spanning their cavities. The arches were observed in EUV lines with formation temperatures as low as 2–4 × 105 K (Oiv
554, Ovi
1032, Ne vii
465), as well as in hotter lines. A statistical test shows that the arcade/instability vs non-arcade/stability association is significant at the 99% confidence level. We suggest 2 types of scenario relating arcades to instabilities. The more preferable scenario is closely related to the Kuperus/Van Tend model of filament disruptions. 相似文献
2.
The catalog of the classical WR stars which have the emission doublet Ovi 3811, 3834 in their optical spectra (the catalog of the WR-Ovi stars) and the results of the spectroscopic investigations of the WR-Ovi stars HD 16523, HD 17638, and HD 192103 are presented. Rapid spectral variability of the emission doublet Ovi 3811, 3834 in the spectra of WR-Ovi stars HD 16523, HD 17638, and of the emission band 3680-3780 Å in the spectra of the WR-Ovi star HD 16523 is observed. It is shown that spectral sub-types of the stars HD 16523 and HD 17638 as estimated from different criteria are uncertain. We argue that the WR-Ovi stars HD 16523 and HD 17638, the optical spectra of which display emission doublet Ovi 3811, 3834, may be considered as WO5 stars. The sub-type WO5 is proposed for the first time. Classification criteria of the WO5 sub-type are represented. The possible contribution of the ions Heii to the emission at 3811 Å and 3834 Å is investigated. Thez-distributions of WR-Ovi stars and WR stars with the probable relativistic companions are found to be similar. 相似文献
3.
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. 相似文献
4.
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. 相似文献
5.
A. Keith Pierce 《Solar physics》1992,139(1):1-12
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. 相似文献
6.
Center-to-limb measurements of the Ca i 6573 intercombination line and the Ca ii 7324 forbidden line are compared with synthetic profiles based on a simple representation of the non-LTE Ca-Ca+ ionization equilibrium. The effects of photoionizations from low lying excited states of neutral calcium are found to reduce the sensitivity of the 6573 center-to-limb behavior as a thermal structure diagnostic. The synthetic center-to-limb behavior is also sensitive to uncertainties in the nonthermal broadening. Nevertheless, the measured center-to-limb behavior of 6573 favors a cool photospheric model similar to the Vernazza, Avrett, and Loeser model M over hotter models based on the Ca ii K wings. The non-LTE calcium abundance obtained from the disk center equivalent widths of 6573 and 7324 using the best fit model is A
Ca2.1±0.2 × 10-6 (by number relative to hydrogen). Applications of these lines as diagnostics of the Ca-Ca+ ionization equilibrium in other stars are briefly discussed.Visiting Astronomer, Kitt Peak National Observatory.Operated by the Association of Universities for Research in Astronomy, Inc. under contract with the National Science Foundation. 相似文献
7.
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. 相似文献
8.
We find that the profile changes observed for the UV emission lines L,Civ 1549, and MgIII 2798, in the Seyfert 1 galaxy Fairall 9 occur mainly near the line centre for L andCiv and in the wings for MgIII. These results indicate that the broad line region (BLR) has a complex structure, possibly with non-spherical components.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain. 相似文献
9.
Theoretical values for the relative intensities of the Fe XIII lines 110747, 110798, and 3388 are presented as functions of electron density using recent values of the cross-section for collisionl excitation by protons. Our results are compared with those of Chevalier and Lambert. 相似文献
10.
A. Keith Pierce 《Solar physics》1991,133(2):215-225
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. 相似文献
11.
Mogens Rudkjøbing 《Astrophysics and Space Science》1969,3(1):102-108
The four diffuse interstellar absorption bands at 4430, 4760, 4890, and 6180 and the two diffuse lines at 5780 and 5797 are interpreted as belonging to pre-ionization transitions in H– and O–, respectively. In both cases the identifications are supported by extrapolations of wave numbers of resonance lines along isoelectronic sequences.In the H– case the hypothesis as to the origin of the bands is supported by quantum-mechanical results byHerzenberg andMandl (1963) as to the positions of resonances in collisions between neutral hydrogen atoms and free electrons. The relatively large intensities of the forbidden transitions indicate that the extent of the ion in its excited states may be very large as compared to ordinary atomic dimensions. In the O– case the relative doublet separation, as extrapolated along the isoelectronic sequence, is used for the identification of the doublet. 相似文献
12.
A high resolution spectrogram of the Mg b2 line from the quiet Sun disc centre is subjected to a coherence analysis. We find that the coherence between intensity fluctuations in the continuum and the wings of the line breaks down at a distance = 0.35 Å from line centre. From this and the r.m.s. intensity contrast as a function of we are led to the following simple model of temperature fluctuation T in the solar photosphere: A lower part (below 50 km, or
5000 > 0.25) with strongly inward increasing T and an upper part (above 50 km) with constant T = 75 K. The two parts are supposed to fluctuate incoherently.Mitteilungen aus dem Kiepenheuer Institut Nr. 166. 相似文献
13.
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. 相似文献
14.
J. Houtgast 《Solar physics》1968,3(1):47-54
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. 相似文献
15.
Slitless flash spectrograms in heights below 8000 km above the solar limb were obtained by the University of Kyoto Expedition at Atar, Mauritania. The integrated intensities of Fexiv
5303, Fex
6374, Fexi
7892, and the continuum are measured as a function of height above the solar limb at eleven points (P.A. = 284–300°) around the third contact point. It is found that a significant amount of the emission in Fex
6374 originates in chromospheric levels well below 8000 km. This implies that the interspicular region of the chromosphere is occupied by coronal material. The average values of the electron temperature and the electron density in the interspicular region are derived from the Fex
6374 and the Fexi
7892 intensities on the assumption of spherical symmetry: T
e = 0.9–1.1 × 106 K and N
e = 9–10 × 108 cm–3. The intensity variations of the coronal lines and the continuum with position angle are also studied. Strong correlations between Fexiv
5303 and the continuum and between Fex
6374 and Fexi
7892 are found. From the Fex
6374 intensities it is inferred that there is a density fluctuation in the innermost corona by at least a factor of two.Contributions from the Kwasan and Hida Observatories, University of Kyoto, No. 271. 相似文献
16.
Monochromatic images in H, H, [Nii] 6584, [Sii] 6717, and [Oiii] 5007 lines are presented for a morphological study of planetary nebulae. Narrow bandpass (=5 to 10Å) interference filters are generally used in order to discriminate peculiar structures existing in different emission lines. However, large bandwidths (=50 Å) along with long exposures, are also necessary in searching for faint nebulosities associated with planetaries.Three faint objects of the Abell's list of old planetary nebulae have been observed through narrow band filters, by means of an image tube (A33, A36 in Chile) or the image photon counting device (A79 at the Haute Provence Observatory). Following the H/[Nii] intensity ratio, a discussion is given about the distance previously derived with some assumptions concerning the measured red fluxes. 相似文献
17.
This work is the continuation of the search for such a cosmological model using which the observed redshift distribution of galaxies in the sample of Broadhurstet al. (1990) turns out to be maximally periodic in the calculated spatial distance. In a previous work, Paálet al. (1992) have demonstrated that among theflat models with non-negative cosmological constant (e.e., vacuum density) the one with a vacuum: dust ratio 2:1 provides the optimum. Now we extend that study to the case of arbitrary space curvature and find equally good periodicity in a surprisingly wide range of models. By use of the dimensionless parameters 0=
0/
crit and
0=/3H
0
2
acceptable periodicity is obtained forall points of the parameter plane within the strip between the parallel lines 0.830–0.30<
0(0)<0.830+0.85(0<1.8), whilst the best periodicities appear along the line
0=0.830+0.39 fitting to the previous optimum at 0=1/3,
0=2/3. Any nonpositive value of
0 gives bad periodicity unless the space curvature is strongly negative and 0<0.4. Fairly good periodicity is observed only in the range of the deceleration parameter –1.2q
0<0.2, corresponding to a small or even negative total gravitational attraction and an expansion time-scale longer than usually expected. 相似文献
18.
In order to study the electron density at the scale of the most encountered structures in coronal active regions a new multichannel coronagraph associated with a photoelectric spectrograph is now used at the Pic-du-Midi Observatory. In its quasi-routine mode this instrument, which is described in this paper, works with a 30 field aperture in a parallel manner with aK-polarimeter. On each observed region it obtains maps of intensities of the
3388, 10747, and 10798 Å emission lines due to Fexiii ion. Each measurement point is associated with a quasi-simultaneous image of the emission corona structures viewed in the light of the5303 Å line of Fexiv. Three examples of observations are given and the capabilities are discussed.Measuring electron density in coronal active regions. II A multichannel photoelectric coronagraph with a photo-electric spectrograph and a reflex monitor at5303 Å.LA du CNRS No. 040285. 相似文献
19.
E. Danezis E. Antonopoulou E. Theodossiou M. Mathioudakis 《Astrophysics and Space Science》1992,187(2):307-318
In this paper we study the far-UV as well as the UV spectrum of the spectroscopic binary system SZ Psc in the wavelength ranges 1235–1950 Å and 2710–3090 Å, respectively, from spectra obtained with the International Ultraviolet Explorer (IUE). The UV spectrum of SZ Psc is mainly an emission spectrum. The short wavelength region includes emission lines formed from the low chromosphere to the transition region (e.g., Siiv,Civ, andNv) and also a deep and broad absorption line of Feii.The Mgii[1] resonance doublet at about 2800 Å presents a P Cygni profile and a multiple structure with two emission and two absorption satellite components. We also present the emission measure diagram in the temperature region 4.4T
e
<53. 相似文献
20.
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. 相似文献