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1.
The ionized gas in NGC 1313 was studied by spectrophotometric means. The radial behaviour of theI(H)/I(6584),I(6717)/I(6731),N(Nii)/N(Hii), andN(Nii)/N(Sii) ratios and the deduced electron densities are discussed. The abundance ratiosN(N)/N(H) andN(N)/N(S) for the nucleus and two emission regions were also derived and compared with previous data.  相似文献   

2.
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.  相似文献   

3.
Among manganese stars, Herculis is of great interest because of the unusual strength of the scandium lines. We present intensity measurements for numerous lines ofCii, Mgi, Mgii, Siii, Caii, Scii, Tiii, Crii, Mni, Mnii, Fei, Feii, Coii, Srii,Yii, and Zrii.  相似文献   

4.
Andersen  T.  Sørensen  G. 《Solar physics》1974,38(2):343-350
Radiative lifetimes have been determined by the beam-foil method for some excited states in the singly ionized rare earths Pr ii, Tm ii, and Lu ii, in order to test the reliability of the transition probabilities and oscillator strengths found by Corliss and Bozman and usually applied for solar abundance determinations. Correction factors of 4.5, 2.5, and 0.3 should be applied to Corliss and Bozman's values for Pr ii, Tm ii, and Lu ii, respectively. These corrections eliminate the discrepancies between the abundance in the solar photosphere and in meteorites for Pr and Tm. Radiative lifetimes for Ce iii are also reported.  相似文献   

5.
The nova-like variable RR Telescopii observed at Cerro Tololo Observatory in 1968 displayed an unusually rich emission line spectrum ranging in excitation from Mgi to [Feviii]. A list of lines with their suggested identifications and approximate intensities covers the range from 3100 to 6700. Only a semi-quantitative discussion is possible since photographic measurements of line intensities could not be calibrated photoelectrically.The spectrum can be interpreted as coming from a highly, inhomogeneous stratified shell illuminated by an extremely hot source. Radiation of Mgi [Oi], [Nii], and [Sii] arises from dense pockets shielded from ionizing radiation. The [Oiii] and [Neiv] radiation appears to originate in strata with densities of the order of 5×106 ions/cm3 and a temperature of the order of 18000 K. The abundance of iron appears to be comparable with that of neon. The helium/hydrogen ratio may be about 0.24.  相似文献   

6.
We have studied high-resolution SWP spectra of AE Aur and 2 Ori A, obtained from the International Ultraviolet Explorer Satellite; and derived curve of growth and column densities ofCii,Cii *, Alii, Siii, Siii *,Sii, Crii, Feii, Niii, and Znii. It has been possible to fit these ions on one empirical curve of growth with a velocity parameterb=13 km s–1 for both stars.Based on the observations made by the International Ultraviolet Explorer (IUE), and collected at the Villafranca Satellite Tracking Station of the European Space Agency.  相似文献   

7.
Additional observations of He ii (304 Å) and Si xi (303 Å) were obtained from a high resolution rocket spectrograph flown on 30 August, 1973 and 20 January, 1975. The profile of the He ii (304 Å) line is everywhere clearly non-gaussian across the solar disk, except in bright active areas. Near the limb, the profile is distinctly reversed. The profile of the Si xi (303 Å) line is essentially gaussian for all regions across the solar disk. Measurements of the He ii/Si xi intensity ratio indicate that the average value of this ratio across the disk depends markedly on solar activity, being about 101 for a moderate level of activity and 301 for a quiet Sun.  相似文献   

8.
The problem of the detection or discovery of RS CVn-type close binary systems with the aid of the magnesium emission doublet 2800 Mgii is discussed. On the example of a star, HD 102077, the possibility of such an approach is shown. The determining factor is the magnitude of the measureless parameterR(Mgii), that is, the relative power of the magnesium doublet emission. For the normal Main-Sequence stars the magnesium emission has a purely chromospheric origin andR(Mgii) 1 (in units of 10–5). However, in the case of close binary systems of RS CVn-typeR(Mgii) 100. Wit the help of IUE it is foundR(Mgii) 100 for the star HD 102077 and, therefore, it is identified with RS CVn-type objects in which the magnesium doublet emission is generated in the intercomponent medium by gaseous matter and is transferred from one component of the system to the other. The basic physical parameters of the intercomponent medium in the case of HD 102077 are obtained.  相似文献   

9.
Ove Havnes 《Solar physics》1970,13(2):323-329
The suggestion that an umbra flash may be caused by a magneto-acoustic wave phenomenon is examined. It is suggested that the flash in Ca ii lines is formed during the compressional stage in a magneto-acoustic wave. The compression which is assumed to be adiabatic will produce a rise in temperature and a corresponding increase in number of Ca ii atoms. The variations in line emission (absorption) coefficient of the Ca ii K-line are calculated on this assumption and are found to be in general agreement with the observed variations. Other observed quantities as proper motion, magnitude of line shift etc., also agree with the wave hypothesis. Further observations which may serve as tests on the wave hypothesis are suggested.  相似文献   

10.
We have calculated for extragalactic Hii regions, the expected relationship between the radio flux at 11 cm and the infrared flux at 11 and 20 m based on the grain models and the parameters which fit the observations of galactic Hii regions. It is shown that the measured infrared fluxes of extragalactic Hii regions are consistent with the expected infrared fluxes for these objects.  相似文献   

11.
A detailed list and analysis of line identifications of five UV spectra of the RS CVn-type binary system TY Pyxidis are presented. These spectra are recorded at different phases with the International Ultraviolet Explorer (IUE). Two of them are in the wavelength range1235–1950 Å while the other three in the range2700–3110 Å.The far-UV spectrum of TY Pyx is mainly an emission spectrum dominated by the emission lines of the ions:Ci, Oi, Cii, Siii, Heii, Alii, and Feiii. We also pointed out the existence of a Feiii [34] line in absorption.The UV spectrum between 2700–3110 Å is dominated by weak absorption lines. Two satellite components are indicated for many lines, which correspond to the two stars of the system, in the two out of the three spectra (LWP 13386 and LWP 13347).Violet emission wings are observed for Fei [1], Tii [1],Oiv [1], and Siiii [1]. The UV spectrum of TY Pyx is also characterized by the multi-structure of Mgii [1] resonance lines.Based on data from the International Ultraviolet Explorer, de-archived from the Villafranca Data Archive of the European Space Agency.  相似文献   

12.
This paper presents the results of monochromatic [Oiii], [Nii], and [Sii] observations of ring nebula Sh157 around the star (WR + B0III) HD 219460 belonging to the Ba 3 cluster. A stratification of radiation typical for photoionization excitation has been revealed. The observations suggest that the Sh157 ring structure may arise as a result of the HD 219460 stellar wind blowing the surroundingHii region, and the bubble age is found to bet(2–5)×105 yr. Three outer envelopes have been distinguished: a weaker extended emission shell apparently blown out by the wind from B-stars of the Ba 3 cluster, and two dust shells which are likely to be associated with NGC 7510 and Cas OB2. The paper is also concerned with the discussion of young star aggregates Ba 3, NGC 7510, Cas OB1, OB2, OB4, OB5, OB7, and Cep OBI and the associatedHii regions, shells and supershells of gas and dust, molecular clouds, and supernova remnants which may be probable members of a single giant stellar complex where the star formation process is in progress.  相似文献   

13.
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   

14.
A sequence of images taken at different positions in the resonance lines of Ca ii, Mg ii, and H i was obtained over a quiescent prominence with the LPSP instrument on OSO-8. Ca ii K (and H) profiles are reconstructed at different locations in the prominence with a (10 × 5) arc sec2 resolution. Significant variations of FWHM and line shifts are found: FWHM range from 0.14 Å to 0.5 Å; blue shifts reach about 14 km s-1. The ratio of K to H absolute intensities shows a large spread around the average value of 1.2. The same ratio for the Mg ii lines in the whole prominence is higher (1.7), a fact already noticed at the edge of an active prominence (Vial et al., 1979). The ionization degree, as measured by the L/Ca K ratio, shows noticeable variations within the prominence. The L intensity is about 0.3 times the intensity measured in the quiet Sun, and the L/L ratio is less than one half the disk value. These results indicate important variations of the thermal conditions inside the prominence.DASOP, Observatoire de Paris, 92190 Meudon, France.  相似文献   

15.
The line profiles of L, Ca ii K and Mg iik were measured with the spectrometer of the Laboratoire de Physique Stellaire et Planétaire on board of OSO-8. The results of these measurements are presented.Mitteilungen aus dem Kiepenheuer-Institut Nr. 181.  相似文献   

16.
In the field partsH, K, L andM of the Orion Nebula, indicated in Figure 2, no obvious differences do appear in the monochromatic photographs obtained in H+[Nii], [Oii], the visual continuum and the range of the Balmer continuum. A different situation we meet in the rest of the field, where one observes two types of featuresA andB, distinguished in Figure 1 by solid and dashed bordering lines respectively. Relative to the conditions in the H+[Nii] pictures, the typeA areas gain in intensity in the photographs taken in the visual continuum. the emission in the forbidden [Oii] lines at 3727 Å is correlated with H+[Nii], the emission in the range of the Balmer continuum with the visual continuum. According to these properties theA-areas must have a particularly high percentage of scattered star light.Most of the areas with identical monochromatic features show a high deficiency of cluster stars correlated with a low surface brightnesss and a reduced gas density. This is explained by an opaqueness of the emission strata in the direction in the line of sight and a position of the same nearer to the observer than the extension of the cluster. There appear surface structures at large distances from the Trapezium which show a correlation between the intensity of scattered star light and the intensity of the emission of the higher ions ([Oiii], [Neiii]). This observation is considered as a proof that canals through the nebular cloud complex allow in some directions the exciting radiation to reach large distances from the star without having suffered an appreciable absorption or scattering.  相似文献   

17.
A calibration previously determined for the evolution of the equivalent width of the emission line H with age for Hii regions (Dottori, 1981) is applied to detached extragalactic Hii regions. The frequency distribution of ages seems to indicate that some of these regions had other bursts of star formation so important as the observed last one.  相似文献   

18.
An empirical relationship between the ratio of the intensities of emission lines in spectra of planetary nebulae, 4686 Heii/H andN 1+N 2[Oiii]/4868 Heii, is established (see Equation (1), curve in Figure 1). A new statistical temperature scale based on this empirical relationship is proposed for the determination of lower limits of the temperatures of the nuclei of planetary nebulae. The well-known method 4686 Heii/H gives the upper level of the temperature of the nucleus. A simultaneous application of both methods has been carried out for 97 planetary nebulae, in order to determine both the upper and lower limits of the temperature of their nuclei (last two columns in Table I). A new quantitative system for the determination of excitation classes of nebulae is proposed (Tables IV and V).  相似文献   

19.
Measures of line intensities from high-dispersion spectrograms of HD 92207, 100262, 125835 and 161912 are presented. Analysis with a theoretical curve of growth leads to the selection of parameters for excitation temperature and microturbulence. The turbulent velocity in the atmosphere of HD 92207 varies through a factor of two in approximately one month, in phase with a similar change in the equivalent width of H. The spectra of the other three stars do not appear to vary, but the turbulent velocity is much less for Fei than for Feii and Crii.  相似文献   

20.
New observations of the [Caii] 7323 Fraunhofer line are reported. The blending H2O line was weak at the time of observation. Accurate estimates of the centre-limb variation of the equivalent width of the [Caii] transition are obtained and shown to be consistent with the calcium abundance log N(Ca) = 6.33.  相似文献   

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