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1.
L. W. Acton R. C. Catura A. J. Meyerott C. J. Wolfson J. L. Culhane 《Solar physics》1972,26(1):183-201
We report some results of a rocket experiment flown on 29 April, 1971. A survey of the solar corona was carried out with a pair of collimated Bragg spectrometers to study the resonance, intersystem and forbidden line emission from the helium-like ions O vii (22 Å) and Ne ix (13 Å). In the direction of dispersion the collimator provided a field of view of 1.7. Also, the continuum radiation near 3 Å was monitored by a collimated proportional counter within a view angle of 4.2. The observed X-ray emission came from the general corona, seven plage regions, and one dynamic feature- the late stage of a small flare. From the intensity of the O vii and Ne ix resonance lines the electron temperature and emission measure of the individual emitting regions are derived on the basis of two models, one (a) in which the region is assumed to be isothermal and another (b) in which the emission measure decreases exponentially with increasing temperature. The latter model, which is the most adequate of the two, yields for the electron temperature of the time-varying feature 2–3 × 106 K, for the other active regions 1.5–2.5 × 106 K, and for the general corona 1.3–1.7 × 106 K. The Ne ix emitting regions are about 1.5 times as hot as the O vii regions. The emission measure ranges from 0.4–2.3 × 1048 cm–3 for all active regions and is about 2 × 1049 cm–3 for one hemisphere of the general corona above 106 K. From an analysis of the ratio, R, of the forbidden and intersystem lines of O vii we conclude that none of the regions producing these lines at the time of the rocket flight had electron densities exceeding about 3 × 109 cm–3. Our data demonstrate a dependence of R upon temperature in agreement with the theory of Blumenthal et al. (1971). The wavelengths for the intersystem, the 1s
22s
2
S
e–1s2p2s
2
P
0 satellite, and the forbidden transition show in the case of Ne ix improved agreement with predictions. The observed strength of the satellite lines for both O vii and Ne ix agrees with the predictions of Gabriel's (1972) theory, which attributes their formation to dielectronic recombination.We are saddened to report the death of A. J. Meyerott on 13 November, 1971. 相似文献
2.
A direct method for determining electron densities from emission line intensities of ions in the beryllium isoelectronic sequence is described and then applied to the analysis of extreme ultraviolet Ciii and Ov spectra from both quiet and active areas in the solar transition region. The results are consistent with a value of N
e
T
e
= 6 × 1014 cm-3K for the quiet Sun at temperatures of 5 × 104 to 3 × 105K. Electron densities are approximately five times greater in active regions than in the quiet Sun. 相似文献
3.
R-matrix calculations of the 11S - 23S and 11S - 23P electron excitation rates in He - like Cv, Ovii, and Mgxi by Kingston and Tayal are used to interpolate results for Neix. Adoption of these in emission line strength calculations leads to values for the density-sensitiveR ratio very similar to those of Pradhanet al. and Wolfsonet al., although the temperature-sensitiveG ratios are approximately 10 to 20 % lower than those deduced by these authors. However the present theoretical value ofG at the temperature of maximum Neix emission,G(T
m) = 0.82, is in excellent agreement with those observed by the SMM and P78-1 satellites for the 1980, November5 flare (G = 0.83 ± 0.01) and nonflaring active regions (G = 0.80 ± 0.05), respectively. 相似文献
4.
The electron collision excitation rates recently calculated for transitions in Si xiii by Keenan et al. (1987) are used to derive the electron temperature sensitive ratio G(=(f + i)/r and the density sensitive ratio R(=f/i), where i, f, and r are the intercombination (1s
2
1
S – 1s2p
3
P
1, 2) forbidden (1s
2
1
S – 1s2s
3
S), and resonance (1s
2
1
S – 1s2p
1
P), transitions respectively. Also estimated are the values of R in the low-density limit (R
0) as a function of electron temperature. The theoretical G ratio at the temperature of maximum emissivity for Si xiii, G(T
m) = 0.70, is in much better agreement with the observed G for the 1985, May 5 flare determined by McKenzie et al. (G = 0.60 ± 0.07) than is the earlier calculation of Pradhan, who derived G(T
m) = 0.85. The error in the observed R
0 ratio is so large that both our result and Pradhan's fall within the acceptable limits of uncertainty and hence one cannot estimate which of the two is the more accurate. 相似文献
5.
Continued spectroscopic observations of Nova Del 67 during 1971 and 1972 show a general decrease of the nebular and coronal emission with respect to the local continuum. The continuous spectrum exhibits a strong Balmer emission (figure 1). Equivalent widths of Hi, Hei, Heii, Oi, [Oi], Oii, [Oii], Oiii, [Oiii], Niii, [Sii], [Aiii], [Neiii], [Nev], [Fevi], [Fevii], [Fex], [Fexi], [Fexiv], [Nixvi], [Nixv] are listed in tables 1 and 2.Figures 5 to 10 show several line profiles, which can be interpreted in terms of a model proposed by Hutchings (1972). Kinematical properties of the nova envelope do not seem to have changed in the 1968–1972 time interval. However, a study of the [Oiii] (4959 Å) line indicates that the physical conditions in the polar blobs in 1972 (T
e=10 660 K,N
e=5,5×105 cm–3) are different from those prevailing in equatorial rings (T
e=9×100 K,N
e=7×105 cm–3).
Le matérial d'observation utilisé pour cette étude a été obtenu à l'aide de téléscopes de 120 cm, 152 cm et 193 cm de l'Observatoire de Haute-Provence (CNRS). 相似文献
Le matérial d'observation utilisé pour cette étude a été obtenu à l'aide de téléscopes de 120 cm, 152 cm et 193 cm de l'Observatoire de Haute-Provence (CNRS). 相似文献
6.
Ion emission line intensities between 1170 and 1700 Å allow one to determine the differential emission measure (DEM) and electron pressure of the plasma in the solar transition region (TR). These line intensities together with their Doppler shifts and line widths are measured simultaneously for the first time above a sunsport from data obtained with the NRL High Resolution Telescope and Spectrograph with 0.06 Å spectral and 1 spatial resolution.The Doppler shifts show both subsonic and supersonic flow in the same line of sight over the umbra. The temperature structure for 40 resolution elements in the sunspot umbra and penumbra is derived from the DEM and the observed electron pressures.Extrapolation of the emission measure curves supports the previous EUV and X-ray observations that coronal plasma above sunspots with T
e>106 K is reduced while emission from TR plasma between 2×105 and 106 K is greatly enhanced relative to quiet or active regions. This enhancement shifts the minimum of the DEM to lower temperatures and increases the slope at 2×105 K by a factor of two.New pressure diagnostics using the emission line intensity ratios of C iv to N iv are presented, and applied to the data.The energy balance in the TR for the sunspot umbra is dominated by radiative losses from the large amount of TR plasma.An estimate of the energy budget shows that an energy input is required to balance the radiative energy losses above the umbra. The observed divergence of the enthalpy flux for the umbral downflows can balance these radiative losses for T
e between 30000 and 200 000 K.A typical umbral model of T
e versus reduced mass column density is compared with one for chromospheric temperatures determined from the Ca H and K lines.Institute of Theoretical Astrophysics, University of Oslo, Norway. 相似文献
7.
Kenneth P. Dere 《Solar physics》1982,77(1-2):77-93
Extreme ultraviolet spectra of several active regions are presented and analyzed. Spectral intensities of 3 active regions observed with the NRL Skylab XUV spectroheliograph (170–630 Å) are derived. From this data density sensitive line ratios of Mg viii, Si x, S xii, Fe ix, Fe x, Fe xi, Fe xii, Fe xiii, Fe xiv, and Fe xv are examined and typically yield, to within a factor of 2, electron pressures of 1 dyne cm–2 (n
e
T = 6 × 1015 cm–3 K). The differential emission measure of the brightest 35 × 35 portion of an active region is obtained between 1.4 × 104 K and 5 × 106 K from HCO OSO-VI XUV (280–1370 Å) spectra published by Dupree et al. (1973). Stigmatic EUV spectra (1170–1710 Å) obtained by the NRL High Resolution Telescope and Spectrograph (HRTS) are also presented. Doppler velocities as a function of position along the slit are derived in an active region plage and sunspot. The velocities are based on an absolute wavelength scale derived from neutral chromospheric lines and are accurate to ±2 km s–1. Downflows at 105 K are found throughout the plage with typical velocities of 10 km s–1. In the sunspot, downflows are typically 5 to 20 km s–1 over the umbra and zero over the penumbra. In addition localized 90 and 150 km s–1 downflows are found in the umbra in the same 1 × 1 resolution elements which contain the lower velocity downflows. Spectral intensities and velocities in a typical plage 1 resolution element are derived. The velocities are greatest ( 10 km s–1) at 105 K with lower velocities at higher and lower temperatures. The differential emission measure between 1.3 × 104 K and 2 × 106 K is derived and is found to be comparable to that derived from the OSO-VI data. An electron pressure of 1.4 dynes cm–2 (n
e
T = 1.0 × 1016 cm–3 K) is determined from pressure sensitive line ratios of Si iii, O iv, and N iv. From the data presented it is shown that convection plays a major role in determining the structure and dynamics of the active region transition zone and corona. 相似文献
8.
Theoretical populations of the 2s3l levels of Ne vii are presented for electron temperatures from 2.5 × 105 K to 4 × 106 K and electron densities from 108 cm–3 to 1012 cm–3. These, in conjunction with intensities of previously observed solar Ne vii lines and wavelengths and intensities observed in the laboratory, are used to identify further Ne vii lines in the solar spectrum. The dependence on temperature of intensity ratios such as I(2s2p
1
P – 2s3d
1
D)/I(2s2p
3
P – 2s3d
3
D) is demonstrated and the advantages of the small wavelength separation of such lines for solar electron temperature diagnostics are discussed. 相似文献
9.
The variation in intensity of the solar X-ray resonance (1s
2
1
S
0 - 1s2p
1
P
1), intercombination (1s
2
1
S
0 - 1s2p
3
P
1), and forbidden (1s2
1
S
0 - 1s2s
3
P
1) lines of helium-like Ovii with 2800 MHz solar radio flux is presented for three solar rotations. A high correlation (r 0.80) exists between the intensities of all three X-ray lines and the 2800 MHz solar flux. The ratio of the forbidden to the intercombination line intensities is found to be essentially independent of long term solar activity. This ratio is used to determine upper limits on the coronal electron density and to make inferences concerning the change in density with solar activity. 相似文献
10.
Iradj Malakpur 《Astrophysics and Space Science》1977,47(1):3-15
After correcting the observed flux of the forbidden lines for the supplementary reddening (due to the circumstellar envelope), we have recalculated the electron density and temperature of the envelope of the Nova. We have determined the temperature and radius of the Nova and obtained values of 1.03×105 K, 1.15×105 K and 1.21×105 K for the temperature and values of 8.49×1010 cm, 4.32×1010 cm and 1.18×1010 cm for the radius of the Nova for 1968, 1969 and 1970, respectively. Using the temperature and radius of the Nova the electron density and temperature of the envelope and the degree of ionization, we have determined the optical depth of the envelope in the Lyman continuum, and found that it is of the order of 10 during the nebular stage.Considering the stratification of the envelope in different regions of ionization, we have determined the radius of the inner and outer edge and the electron temperature of every region. We found that the electron temperature of the inner part of the envelope is at least three times greater than that of the outer part. The variation of electron temperature as a function of the radius of the ionization region considered shows an abrupt increase of theT
e whenR/R
out(env) is between 0.44 and 0.54. 相似文献
11.
We studied the morphology and spatial distribution of loops in an active region, using coordinated observations obtained with both the S082A XUV spectroheliograph and the S056 grazingincidence X-ray telescope on Skylab. The active region loops in the temperature range 5 × 105 –3 × 106 K fall basically into two distinctive groups: the hot loops with temperatures 2–3 × 106 K as observed in coronal lines and X-rays, and the relatively cool loops with temperature 5 × 105 –1 × 106 K as observed in transition-zone lines (Ne vii, Mg ix). The brightest hot coronal loops in the active region are mostly low-lying, compact, closely-packed, and show greater stability than the transition-zone loops, which are fewer in number, large, and slender. The observed aspect ratio of the hot coronal loops is in the range of 0.1 and 0.2, which are almost two orders of magnitude larger than those for the Ne vii loops. Brief discussion of the MHD stability of the loops in terms of the aspect ratio is presented. 相似文献
12.
We present the results of an analysis of the winds of two WC10 central stars of planetary nebulae, CPD-56°8032 and He 2-113. These two stars have remarkably similar spectra, although the former exhibits somewhat broader emission line widths. High resolution spectra (up to R=50 000) were obtained in May 1993 for both objects at the 3.9 m AAT, using the UCL Echelle Spectrograph. The fluxes in individual Cii auto-ionising multiplet components, many of which were blended, were derived. Lines originating from auto-ionising resonance states situated in the C2+ continuum are very sensitive to the electron temperature, since the population of the these levels is close to LTE. The measured widths and profile shapes of these transitions are presented and are in excellent agreement with those predicted on the basis of their calculated auto-ionising lifetimes. The wind electron temperature is derived for both stars from the ratio of the fluxes in four such transitions (T
e
=18 500 K±1 500 K for CPD-56° 8032 andT
e
=13 600 K±800 K for He 2-113). Optical depth effects are investigated using normal recombination lines to obtain an independent wind electron temperature estimate in excellent agreement with the dielectronic line analysis. 相似文献
13.
Recent R-matrix calculations of electron excitation rates for Mg vii and Si ix are used to determine the theoretical density sensitive emission line ratios R
1= I(2s2p
3
1
D
0 - 2s
2
2p
2
1
D
e
)/I(2s2p
3
3
S
0 - 2s
2
2p
2
3
P
2
e
) and R
2= I(2s2p
3
1
P
0 - 2s
2
2p
2
1
D
e
)/I(2s2p
3
3
S
0 - 2s
2
2p
2
3
P
2
e
). These are found to be quite similar to the earlier results of Mason and Bhatia. Electron densities derived using observed R
1 and R
2
ratios from Skylab NRL XUV spectra of solar flares and active regions are in good agreement, and compare favourably with those deduced from ions formed at similar electron temperatures to Mg vii and Si ix. 相似文献
14.
R-matrix calculations of electron impact excitation rates for transitions in Si iii are used to derive the electron-density-sensitive emission line ratios R
1 = I(1113.2 Å)/I(1206.3 Å), R
2 = I(1298.9 Å)/I(1206.3 Å), and R
3 = I(1296.7 Å)/I(1206.3 Å). A comparison of these with observational data for several solar features obtained with the Harvard S-055 spectrometer on board Skylab reveals that theory and experiment are compatible if the electron temperature of the Si iii emitting region of the solar atmosphere is log T
e
= 4.5, but not if log T
e
= 4.7. The implication of the choice of a lower temperature on the electron energy distribution function is also briefly discussed. 相似文献
15.
Victor Mansfield 《Astrophysics and Space Science》1969,3(2):292-300
Radio measurements of the electron temperature ofHii regions are obtained from the ratio of the brightness temperature of a hydrogen recombination line to that of the adjacent continuum, while optical measurements are obtained from the ratio of [Oiii] forbidden-line intensities. The radio and optical measurements made under the assumption of an isothermalHii region,T
R andT
opt respectively, are combined to derive a temperature distribution for an entire nebula. A sphericalHii region in local thermodynamic equilibrium with constant density which is optically thin in both the line and the continuum is used as a model. Assuming linear temperature gradients withT
R=6000K andT
opt=10000K, it is found thatT=12000K (1–0.74r/R), wherer is the distance from the center andR is the radius of the nebula. 相似文献
16.
Spectrographic observations of the flash spectrum were made by the Kwasan Observatory at the total solar eclipse on 7 March, 1970. The integrated intensities of Fexiv 5303, Fex 6374, and the continuum were measured on the spectrograms as a function of height above the Sun's limb. It was found that a large amount of emission in the coronal lines originates in the interspicular regions of the chromosphere. Analysis of the data yielded that the interspicular regions consist of coronal material of T
e = 1.6 × 106–1.2 × 106 and log N
e = 8.5–9.5, and that a decrease in T
e and an increase in N
e occur with decreasing height. 相似文献
17.
Tokio Tsubaki 《Solar physics》1975,43(1):147-175
A technique developed for analysing line profiles with both speed and high accuracy was used to study the physical conditions
of a coronal formation near a quiescent prominence. Detailed analyses of five coronal lines (Fe xiv λ 5303, Fe x λ 6374, Ni xv λ 6702, Fe xv λ 7059, and Fe xi λ 7892) provided total intensities, Doppler width temperatures, ionization temperatures, and velocities.
Dissimilar spatial fluctuations in intensity are obvious for ions grouped according to (low vs high) ionization potentials.
The intensity of the green line shows a local minimum around the observed quiescent prominence; a corresponding but much more
diffuse pattern is visible in the red line intensity.
Large differences are observed in temperatures derived by different means. In particular,
, while
, and
. The differences between
and
are taken as direct evidence of temperature inhomogeneity. One can thus put little significance in T
e
(xi/x). T
D(λ5303) and T
e
(xv/xiv) fluctuate nearly in parallel at each slit height, with a weak local minimum evident around the prominence. The discrepancy
between these two can be removed if a non-thermal turbulent motion of 6–16 km s−1 is assumed. Variations with height of both T
D(λ5303) and T
e
(xv/xiv) suggest that the coronal temperature maximum is located no more than 15000 km above the top of spicules. A negative gradient
of about 6 deg km−1 is found in the height variation of T
D(λ5303).
The height variation of the green line wavelength shows that the majority of coronal material in this region is flowing from
west to east on the Sun, with the highest velocity of 12 km s−1 found at the lowest heights. This motion is in the same sense as that of the nearby coronal rain, as determined both from
the spectra and wavelength-shifted Hα filtergrams. Superposed on the above flow is a systematic velocity field of up to ±5
km s−1. This field similarly reaches maximum amplitudes at lowest heights showing a local maximum around the prominence.
On leave from Institute of Earth Science and Astrophysics, Shiga University, Ohtsu 520, Japan, as 1973–75 National Academy
of Science/National Research Council Senior Post-Doctoral Research Associate at Sacramento Peak Observatory. 相似文献
18.
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
19.
A. I. Poland M. E. Machado C. J. Wolfson K. J. Frost B. E. Woodgate R. A. Shine P. J. Kenny C. C. Cheng E. A. Tandberg-Hanssen E. C. Bruner W. Henze 《Solar physics》1982,78(2):201-213
Simultaneous observations of a solar limb flare in the X-ray and ultraviolet regions of the spectrum are presented. Temporal and spectral X-ray observations were obtained for the 25–300 keV range while temporal, spectral, and spatial X-ray observations were obtained for the 30–0.3 keV range. The ultraviolet observations were images with a 10 spatial resolution in the lines of O v (T
e 2.5 × 105 K) and Fe xxi (T
e 1.1 × 107 K). The hard X-ray and O v data indicate that the impulsive phase began in the photosphere or chromosphere and continued for several minutes as material was ejected into the corona. Impulsive excitation was observed up to 30 000 km above the solar surface at specific points in the flare loop. The Fe xxi observations indicate a preheating before the impulsive phase and showed the formation of hot post-flare loops. This later formation was confirmed by soft X-ray observations. These observations provide limitations for current flare models and will provide the data needed for initial conditions in modeling the concurrent coronal transient. 相似文献
20.
K. M. Aggarwal 《Solar physics》1984,94(1):75-84
Using theR-matrix approach new calculations have been made for the electron impact excitation of the fine structure transitions within the 1s
22s
22p
2 ground configuration of Mgvii. The computations have been made at a large number of energies in order to account for the contribution of resonances. All partial waves withL 9 are included in the calculations which are considered to be sufficient for the convergence of collision strengths in the energy range below 65 Ry. From this collision strength data, excitation rate coefficients have been calculated at a series of electron temperatures which are employed in the computation of population of the five lowest levels of Mgvii. The line intensity ratios for the transitions3
P
1 1
D
2 and3
P
2 1
D
2 to3
P
1 1
S
0 are then calculated in the temperature range of 105 to 107 K at electron densities in the range 106 to 1010 cm–3. The calculated values are in good agreement with the earlier available results. 相似文献