共查询到20条相似文献，搜索用时 2 毫秒
1.
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
2.
I. G. Kovalenko Yu. A. Shchekinov Al. A. Suchkov 《Astrophysics and Space Science》1989,152(2):223-238
The available data speak in favour of space and time inhomogeneity of gaseous corona of our Galaxy. The observedCIV and SiIV ions are formed mainly by fast photons and localized inHII-clouds of the galactic halo. On the other hand, theNV ions are thermally ionized and localized in the gas corresponding to a transformation of hot intercloud coronal gas in theHII-clouds. TheHII-clouds exhibit downward the gas flow. The galactic fountain can eject the interstellar matter up to height of 1 kpc. Such ejections may be also displayed inCIV, SiIV, and partiallyNV, and partiallyNV absorptions. But large gaseous corona extending up to 3–5 kpc proves to be mass-unbalanced. It is possible that the existence of corona is evidence for violent star formation in the galactic disc in the recent past. 相似文献
3.
The heights of formation of a number of extreme ultraviolet lines in active regions have been measured from OSO-IV spectroheliograms. Using the Lyman continuum at 2000 km above the white light limb as a reference, we find heights for Hei, Heii, Ciii, Niii, Oiv, Ovi, Neviii, Mgx, Sixii, Fexv and Fexvi that are in approximate agreement with models based on analysis of EUV emission intensities. The height of Cii is anomalously high. The accuracy of measurement is typically about 2000 km. The data suggest that the transition zone is less steep than calculated from EUV emission intensities; however, higher resolution observations are necessary to resolve the discrepancy. 相似文献
4.
M. Mamadazimov 《Solar physics》1972,22(1):129-136
The fine structure of the Evershed effect was studied using spectrograms obtained on 3 July 1969 at the Pulkovo Observatory. The results of the study of Fei and Cai lines show that the outward motion in the penumbra is concentrated only in dark filaments. It is supposed that interfilamentary spaces are parts of the photosphere not covered by dark filaments. The velocity variation along a few dark filaments shows that maximum velocity is at a distance 0.8 Rs from the center of the sunspot. The mean velocity in the interfilamentary elements is of the same order as that in the photosphere directly adjoining the penumbra. The results of measurement in Ti ii, Fe ii and CH lines show that in the colder upper part of the penumbra (CH) the velocity is greater than the velocity measured in the deeper layers (Feii and Tiii). The mean velocity at the outer boundaries of the dark filaments (Tii) is 1.5–2.0 km/s. 相似文献
5.
In this paper we study the main features of the far UV spectrum of the binary star AX Mon, observed with the IUE satellite at phase 0.568.Ions indicating a large range of ionization stages, going fromCi,Oi,Ni toSiv,Civ,Nv are present.The spectrum is dominated by shell absorption lines of Feii, Feiii, Siiii,Cii, Alii, Mgii and Niii.Two satellite components are clearly indicated in all these lines except for Niii which presents only one. Their mean velocities are +10±5 km s–1, –75±10 km s–1, and –260±15 km s–1.Red emission wings are observed in the Mgii resonant doublet at 2800 Å, which shows a P Cygni profile. Each of the absorption lines of the Mgii doublet is formed by a narrow component, which is blended with the Mgii interstellar line and a broad component, which shows a complex structure.Broad and asymmetrical profiles are observed for the Siiv,Civ, andNv resonance lines with blue edge velocities about –700±30 km s–1. 相似文献
6.
Walter Van Rensbergen 《Solar physics》1967,1(3-4):354-360
The existence of doubly excited levels causes dielectronic recombination and autoionization. These effects influence respectively the total recombination rate and the total ionization rate of different ions. The ratios of dielectronic recombination to radiative recombination and of autoionization to collisional ionization are given as a function of the electron temperature for the term systems of Oiv, Ov, Ovi, Siix and Fexv. While autoionization can contribute appreciably to the total ionization rate, dielectronic recombination is always the most effective recombination mechanism. 相似文献
7.
High resolution spectroheliograms in the ultraviolet emission lines He i, He ii, O iv, O v, and Ne vii have been photographed during a sounding rocket flight. Simultaneously, broad band filtergrams of the far ultraviolet solar corona were obtained from the same flight. This paper describes qualitatively the spatial distribution of the UV emission. A comparison with an H filtergram is made. The most significant results can be summarized as follows: We find most of the ultraviolet emission concentrated around spicules, with different degree of concentration, decreasing with higher temperatures. 4 different areas of ultraviolet emission can be distinguished. (1) The normal network, bright in all UV emission lines from the chromosphere into the corona. (2) The coronal holes, bright in all UV emission lines up to 600 000 K but depressed in coronal lines from 1 million degrees upward. (3) The coronal depressions near active centers, absence of all ultraviolet emissions and (4) Active regions, where ultraviolet emission comes from plages, sunspots and coronal loops. High non-thermal Doppler velocities can be found in certain plage kernels around 105 to 2 × 105 K. Sunspots are bright in the ultraviolet, but do not exhibit He i or He ii emission. The corona above sunspots is weak. Sunspots do not show high non-thermal Doppler velocities. The He i and He ii emission does not follow either chromospheric, transition zone or coronal pattern; one can recognize some typical behavior of each. 相似文献
8.
Ionization equilibrium is a useful assumption which allows temperatures and other plasma properties to be deduced from spectral observations. Inherent to this assumption is the premise that the ion stage densities are determined solely by atomic processes which are local functions of the plasma temperature and electron density. However, if the time scale of plasma flow through a temperature gradient is less than the characteristic time scale for an important atomic process, deviations from the ionization stage densities expected for equilibrium will occur which could introduce serious errors into subsequent analyses. In the past few years, significant flow velocities in the upper solar atmosphere have been inferred from observations of emission lines originaing in the transition region (about 104–106 K) and corona. In this paper, three models of the solar atmosphere (quiet Sun, coronal hole, and a network model) are examined to determine if the emission expected from these model atmospheres could be produced from equilibrium ion populations when steady flows of several kilometers per second are assumed. If the flows are quasi-periodic instead of steady, spatial and temporal averaging inherent in the observations may allow for the construction of satisfactory models based on the assumption of ionization equilibrium. Representative emission lines are analysed for the following ions: C iii, iv, O iv, v, vi, Ne vii, viii, Mg ix, x, Si xii, and Fe ix–xiv. Two principle conclusions are drawn. First, only the iron ions are generally in equilibrium for steady flows of 20 km s–1. For carbon and oxygen, ionization equilibrium is not a valid assumption for steady flows as small as 1 km s–1. Second, the three models representing different solar conditions behave in a qualitatively similar manner, implying that these results are not particularly model dependent over the range of temperature gradients and electron densities thus far inferred for the Sun. In view of the flow velocities which have been reported for the Sun, our results strongly suggest caution in using the assumption of ionization equilibrium for interpreting spectral lines produced in the transition region.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
9.
L. W. Acton J. L. Culhane A. H. Gabriel R. D. Bentley J. A. Bowles J. G. Firth M. L. Finch C. W. Gilbreth P. Guttridge R. W. Hayes E. G. Joki B. B. Jones B. J. Kent J. W. Leibacher R. A. Nobles T. J. Patrick K. J. H. Phillips C. G. Rapley P. H. Sheather J. C. Sherman J. P. Stark L. A. Springer R. F. Turner C. J. Wolfson 《Solar physics》1980,65(1):53-71
The 1.4–22.4 Å range of the soft X-ray spectrum includes a multitude of emission lines which are important for the diagnosis of plasmas in the 1.5–50 million degree temperature range. In particular, the hydrogen and helium-like ions of all abundant solar elements with Z > 7 have their primary transitions in this region and these are especially useful for solar flare and active region studies. The soft X-ray polychromator (XRP) is a high resolution experiment working in this spectral region. The XRP consists of two instruments with a common control, data handling and power system. The bent crystal spectrometer is designed for high time resolution studies in lines of Fe i-Fe xxvi and Ca xix. The flat crystal scanning spectrometer provides for 7 channel polychromatic mapping of flares and active regions in the resonance lines of O viii, Ne ix, Mg xi, Si xiii, S xv, Ca xix, and Fe xxv with 14 spatial resolution. In its spectral scanning mode it covers essentially the entire 1.4–22.5 Å region.This paper summarizes the scientific objectives of the XRP experiment and describes the characteristics and capabilities of the two instruments. Sufficient technical information for experiment feasibility studies is included and the resources and procedures planned for the use of the XRP within the context of the Solar Maximum Mission is briefly discussed. 相似文献
10.
M. J. Stift 《Astrophysics and Space Science》1977,46(2):465-469
A detailed analysis of the multiplet structure of lines used for observations of stellar magnetic fields is presented. It is shown that LS-coupling does not hold good for many of the spectroscopic terms of Tiii and Crii and that the magnetic fields observed in several magnetic stars are strong enough to produce transition to the Paschen-Back effect in some of these lines. In order to avoid possible erroneous results it is recommended that only lines originating from Russell-Saunders terms be used for magnetic observations. A list of Tiii, Crii and Fei lines is given which should not be used in measuring strong magnetic fields in magnetic stars. 相似文献
11.
E. L. Van Dessel 《Solar physics》1975,44(1):13-24
Eclipse observations of total line intensities (Cr i: two groups of lines; Ti ii, Fe ii and Cr ii: two lines each) are interpreted in terms of departures from LTE. The same method as described in Paper III (van Dessel, 1974) is used. The HSRA model is used to compute the LTE populations. A distribution of NLTE-coefficients is obtained for each group of lines. The lines discussed in the present paper are seen to remain in emission down to some 1000 km inside the limb. As a consequence, interpretation is less simple than for the Fe i lines (Paper III); population and excitation temperatures are found to be rather divergent from Holweger's temperature, which was used for a first approximation. 相似文献
12.
Bengt Edlén 《Solar physics》1969,9(2):439-445
A study of theZ-dependence of the2
P intervals of 2s
22p and 2s
22p
5, aided by recent observational results, confirms the identification in the coronal spectrum of λ 4412 with Arxiv, and of λ 5533.4 with Arx. It is further shown that transitions from metastable levels in the configurations 3s
23p
k 3d, withk=3, 4 and 5, of Fexi,x, ix, and Nixiii, xiii, xi can well account for the remaining unidentified coronal lines. 相似文献
13.
The radial velocity variations of the components of someOii, Siiii, andNii lines in P Cyg spectrum are investigated during the period 1981–1983. All data are analyzed in terms of a model which implies a multiple ejection of shells in the stellar wind. It is shown that the observed phenomenon is not periodic, but it occurs on a time-scale between 110 and 160 days with the most frequently observed length of the cycle of about 110 days. The shells move away from the star with an acceleration that is greater at low velocities than at high ones. The radial velocity variations ofOii, Siiii, andNii lines agree with these of hydrogen lines if we assume velocity and excitation condition differences inside the shell. 相似文献
14.
Guiquing Zhang 《Solar physics》1994,154(1):41-49
Wavelength coincidences are noted between laboratory and solar spectral line lists for the twenty-electron ions CaI, TiIII, CrV, MnVI, FeVII, and NiIX, which imply likely identifications for a large number of unidentified lines in the solar lists. These identifications should
be useful, e.g., for improving chromospheric/coronal abundance estimates of the less abundant elements titanium, chromium,
and manganese. 相似文献
15.
F. Baudin E. Ibarra E. H. Avrett J.-C. Vial K. Bocchialini A. Costa P. Lemaire M. Rovira 《Solar physics》2007,241(1):39-51
We present SUMER/SOHO UV measurements of chromospheric oscillations of intensity, velocity, and linewidth observed in C i, S i, O i, and C ii lines, which are formed in the altitude range from 1000 km to 2000 km above τ
500=1. Oscillations in lines originating at similar altitudes exhibit different behaviors which we discuss in terms of the formation
of the lines. 相似文献
16.
H. Hüseyin Mentese 《Astrophysics and Space Science》1992,187(1):127-133
We have studied the interstellar column densities of Alii, Siii,Sii, Feii, Niii, and Znii in the direction of 18 O- and 6 B-type stars so as to improve the relations of element depletions withE(B-V), and to look for other possible relations with two stellar parameters: namely, the rate of mass loss and rotational velocity. The stars were chosen in order to cover several directions in the Galaxy, as well as a wide range in interstellar reddening. We found a clear inverse trend relating the abundance of elements to interstellar reddening. 相似文献
17.
Data are presented from a spectral and photometric study of the long-period variable star Y Ori, which we have classified
as a type M7IIIe near its brightness minimum. In the blue part of the spectrum, features from a star of an earlier spectral
class are superimposed on the spectrum of a cool giant, so that a variable excess emission is observed at wavelengths of 4000–4200
Å. As opposed to the monotonically decreasing intensity of the Balmer lines (EWHα > EWHβ > EWHγ > EWHδ) in normal stars belonging to the earlier spectral classes, a reverse relationship, with EWHγ < EWHδ is detected in Y Ori.
Translated from Astrofizika, Vol. 51, No. 4, pp. 567–575 (November 2008). 相似文献
18.
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
19.
The rare-earth ions cerium ii, lanthanum ii, dysprosium ii, and additionally zirconium ii and iron ii, are seen as weak emission features in the wings of the solar Ca ii H and K lines. The strength of these emission lines increases on the disk toward the limb. We provide recent high-resolution
observations at disk center and at the limb. The identity of the weak lines is re-worked. We point out the unique role of
eclipse spectra in distinguishing between the photospheric and chromospheric origins of emission lines. It is then demonstrated
from our full disk (Sun-as-a-Star) and center disk archives, 1974 – 2010, that no activity cycle related signal is evident
(save for the H and K lines themselves). 相似文献
20.
Werner M. Neupert 《Solar physics》1971,18(3):474-488
Observations of solar X-ray line emission using crystal spectrometers during a large chromospheric flare have provided a list of wavelengths with a precision of 0.003 Å in first order of diffraction and correspondingly better in higher orders. In addition to the resonance, intersystem (1 1
S
0-2 3
P
1) and forbidden (1 1
S
0-2 3
S
1) transitions of ions of the Hei isoelectronic sequence, we have recorded satellite lines arising from ions in the Lii, Bei and Bi isoelectronic sequences. These satellite features are most prominent in the iron spectrum. Apparent decreases in the ratio of forbidden and intersystem line intensities of Mgxi and Sixiii during the flare are used to derive electron densities possibly as high as 1 × 1013 cm–3 in the Mgxi emitting region and 1 × 1014 cm–3 in the Sixiii region during the event. A search for satellite lines on the long-wavelength side of the Lyman-alpha line of Hi-like ions has yielded no positive identifications. 相似文献