首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
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.  相似文献   

2.
Quiescent prominences It is found that Heii 4686 is emitted in the same cold region of 10000 K as hydrogen, metal and neutral helium emission lines. This conclusion is based on the finding that the observed width of 4686 is the same as the calculated width of 4686. The calculated width is derived from the observed widths of hydrogen and metallic lines. The large intensity of Heii 4686 in 10000 K can be explained by the ionization of Heii due to the UV radiation below 228 Å that comes from the corona and the transition region.Loop prominences The very broad width (30 to 50 km s–1) of 4686 for two post-flare loop prominences shows that the Heii line is emitted in hot regions different from regions of hydrogen and metal emission. From the widths of the Balmer lines and many metallic lines the kinetic temperature for one loop is found to be 16000 K in one part and 7600 K in another part. The electron densities are 1012.0 cm–3 and less than 1011.0 cm–3 respectively.Chromosphere The intensity of 4686 in the chromosphere can be interpreted in terms of a temperature of 10000 K with the ionization due to UV radiation. But, since observations of the width of 4686 are not available, a definitive conclusion for the chromosphere cannot be reached.  相似文献   

3.
We report an unsuccessful search for the He+ 4686 line in the low chromosphere. However, at the location of this line we detect a number of other chromospheric emission lines. This leads us to the conclusion that the He+ 4686 identification made in the past, as well as other identifications, are probably in error. Additionally the region of the neutral helium 4713 line is also studied.On leave from Tokyo Astronomical Observatory, Mitaka, Japan.  相似文献   

4.
The WN5 star HD 50896 is a well known variable star but the cause of the variations is uncertain. As part of an extensive observing campaign on HD 50896, 68 spectra were obtained with the AAT and UCL echelle spectrograph over three nights in January 1991. The variations seen in the emission line profiles of He II 4686, He II 4860, N V 4945 and N V 4603, 4620, sampling different regions of the wind, are described. Gross night-to-night changes are seen in the tops of all the emission lines, with the pattern of variability being different for each line, as a consequence of the different line formation regions. The edges of the emission line profiles are seen to shift but not in a systematic way, as expected for binary motion. In terms of hourly variations which monitor the propagation of instabilities in the wind, distinct blobs are seen moving outwards through the emission line profiles of the He II lines but are absent in NV 4945. This appears to indicate that, at least for the epoch of these observations, the instabilities develop farther out in the wind than the N V formation region and may well rule out photospheric-induced wind instabilities.  相似文献   

5.
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   

6.
The plasma-laser star model for quasars, which is based on the hypotheses that there is no red shift in the spectra of quasars and that the strength of the emission lines is due to laser action, is further developed. Continuity is shown to exist between the spectra of Ovi sequence planetary nuclei, Sanduleak stars, and 10 quasars. The Ovi 3811, 3834 and Heii 4686 emission lines in the spectra of these 10 quasars are identified. Candidate identifications for other quasar lines are also suggested. Making use of the similarity between the spectra of Ovi sequence planetary nuclei and those of the 10 quasars, absolute magnitudes, temperatures, and masses of these quasars are estimated. The distribution of quasars in galactic coordinates is also discussed. Three predictions are made.  相似文献   

7.
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.  相似文献   

8.
A list of 171 stars in the galaxy M33 is presented. The stars could be considered as candidates for unique objects, such as SS 433, S Dor, P Cyg stars and possibly new kinds of peculiar objects. All these stars have been selected on the basis of the similarity to SS 433, free from interstellar absorption: OB star with strongH emission or with HeII 4686 and CIII, NIII 4630 - 4660 emission lines; a hot star inside a supernovae remnant or radio nebula. The variability of these stars has been used as an additional criterion of the selection. It is important to carry out spectral observations of the presented stars, which will allow us to select stars with intrinsicH emission.  相似文献   

9.
We analyze the emission component of galaxy nuclei at very low intensity levels (W(H)2Å). This emission level is considerably lower than that of classical LINERS like NGC 1052. We have access to weaker emission lines by averaging spectra with similar line ratios for H [NII], and [SII]. From the resulting spectrum for very low level emission nuclei, the [SII] 6717, 6731/[SIII] 9069, 9532 line ratio criterion (Diazet al., 1985a) unambiguously shows that shock-wave heating is the mechanism responsible for the ionization in such objects.  相似文献   

10.
The observations of the reddening of the distant galaxies and the weak diffuse radiation in the clusters of galaxies can be interpreted as a consequence of the presence of dust grains in the intergalactic medium. When allowance is made for the destruction of the grains in collision with particles of the hot gas, its lifetime is about 107–108 yr at a gas concentrationn g 10–3 cm–3. The detection of the infrared (IR) emission from the galaxy clusters might be the test for the proof of the presence of dust grains in the intergalactic medium. In this paper the estimates of the expected intensities and fluxes of IR emission for the spectral region 50–300 are presented for two galaxy clusters in Coma and Perseus. The parameters of the hot gas spatial distribution are chosen from X-ray observations. Having assumed that intergalactic dust can be ejected only from the galaxies, we used such a model for intergalactic dust grains which explains very well the interstellar dust effects. It is shown that the dust temperature, which is determined from the general energetic balance of the dust grains, can achieve some scores of degrees of Kelvin. Two models of the dust spatial distribution are considered. It is found that the maximum of IR flux for the Coma cluster lies near =100 and the same for the Perseus cluster near 50–70. The total fluxes of IR emission from these clusters are about 105–106 Jy and can be detected by modern observational methods.  相似文献   

11.
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   

12.
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   

13.
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   

14.
The results of new spectral observations of the Seyfert component of the close binary galaxy with UV excess Kaz 163 are presented. Two new spectra have been obtained: with the 3-m telescope of Lick Observatory in 1986 and with the 1.8-m telescope of Asiago Observatory in 1993. It is shown that there was no short-term (about one month) variability in the spectrum. The emission lines Hell 4686 and Hel 5876 strengthen significantly between 1984 and 1986.Translated fromAstrofizika, Vol. 37, No. 1, pp. 5–12, January–March, 1994.  相似文献   

15.
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   

16.
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.  相似文献   

17.
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   

18.
Den Hartog  E. A.  Curry  J. J.  Wickliffe  M. E.  Lawler  J. E. 《Solar physics》1998,178(2):239-244
We report spectroscopic measurements on the 6s6p 3P1 level of Lu+ at 28503.16 cm-1. The radiative lifetime of this level was measured to be 37.4 ± 1.9 ns using time-resolved laser-induced fluorescence of a slow ion beam. Branching fractions were determined from Lu spectra recorded using the 1.0 m Fourier transform spectrometer at the National Solar Observatory. Thelog(gf) values determined by combining the radiative lifetime and branching fractions for the 3507.39, 5983.90, and 6221.87 (air wavelengths) lines are - 1.16 ± 0.03, - 1.16 ± 0.06, and -0.76 ± 0.04, respectively. The 6221.87 line has been identified by Bord, Cowley, and Mirijanian (1997) as the best candidate for the determination of the solar lutetium abundance because it is only slightly blended in the solar spectrum. The present 6221.87 transition probability measurement brings their solar lutetium abundance into good agreement with the CI chondrite abundance.  相似文献   

19.
Ratios of emission line intensities are used to calculate the variation of temperature and the variation of electron density as a function of ion class for differing paths through a coronal enhancement. The data indicate (a) a peak mean electron density of 2.3 × 109 cm–3, (b) a temperature maximum greater than 2.3 × 106 K, and (c) the non-coincidence of the peak temperature and peak mean electron density. The latter demonstrates the invalidity of the assumption of symmetric models for coronal enhancements.The abundance of Ni was found to be equal to 0.045 that of Fe from the line ratio I( 6702)/ /I( 7059) and a density model based on the variation of the ratio I( 8024)/I( 6702).  相似文献   

20.
Fredvik  T.  Maltby  P. 《Solar physics》1999,184(1):113-132
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.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号