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1.
Closely spaced microphotometer tracings parallel to the dispersion of one excellent frame of a K-line time sequence have been utilized for a study of the nature of the K2v , K2R intensities in the case of the solar chromosphere. The frequency of occurrence of the categories of intensity ratio are as follows: per cent; per cent; per cent; per cent; per cent. Two types of absorbing components are postulated to explain the pattern of observed K2v , k2R intensity ratios. One component with minor Doppler displacements acting on the normal K232 profile, where K2V >K2R , produces the cases K2v K2R , K2v = K2R , K2v <K2R . The other component arises from dark condensations which are of size 3500 kms as seen in K2R . They have principally large down flowing velocities in the range 5–8 km/sec and are seen on K3 spectroheliograms with sizes of about 5000 kms, within the coarse network of emission. These dark condensations give rise to the situation K2R = 0.K2-line widths are measured for all tracings where K2v , K2R are measurable simultaneously. The distribution curve of these widths is extremely sharp. The K2 emission source is identified with the bright fine mottles visible on the surface. Evidence for this interpretation comes from the study of auto-correlation functions of K2 intensity variations and the spacing between the bright fine mottles from both spectrograms and spectroheliograms. The life time of the fine mottling is 200 sec.The supergranular boundaries which constitute the coarse network come in two intensity classes. A low intensity network has the fine mottles as its principal contributor to the K emission. When the network is bright, the enhancement is caused by increased K emission due to the accumulation of magnetic fields at the supergranule boundary. The K2 widths of the low intensity supergranular boundary agree with the value found for the bright mottles. Those for the brighter network are lower than this value, similar to the K2 widths as seen in the active regions.It is concluded that bright fine mottling is responsible for the relation, found by Wilson and Bappu, between K emission line widths and absolute magnitudes of the stars.The paper discusses the solar cycle equivalents that stellar chromospheres can demonstrate and indicates a possible line of approach for successful detection of cyclic activity in stellar chromospheres.  相似文献   

2.
We propose a multicomponent analysis of starburst galaxies, based on a model that takes into account the young and evolved stellar components and the gas emission, with their respective extinction, in the frame of a coherent dust distribution pattern. Near-IR signatures are preferentially investigated, in order to penetrate as deep as possible into the dusty starburst cores. We computed the 1.4-2.5 μm spectra of synthetic stellar populations evolving through strong, short timescale bursts of star formation (continuum and lines, R ? 500). The evolution model is specifically sensitive to cool stellar populations (AGB and red supergiant stars). It takes advantage of the stellar library of Lançon & Rocca-Volmerange (1992) [A&ASS, 96, 593], observed with the same instrument (FTS/CFHT) as the analysed galaxy sample, so that the instrumental effects are minimised. The main near-IR observable constraints are the molecular signatures of CO and H2O and the slope of the continuum, observed over a range exceptionally broad for spectroscopic data. The H - K colour determined from the spectra measures the intrinsic stellar energy distribution but also differential extinction, which is further constrained by optical emission line ratios. Other observational constraints are the near-IR emission lines (Brγ, He I 2.06 μm, [Fe II] 1.64 μm, H2 2.12 μm) and the far-IR luminosity. The coherence of the results relies on the interpretation in terms of stellar populations from which all observable properties are derived, so that the link between the various wavelength ranges is secured. The luminosity LK is used for the absolute calibration.We apply this approach to the typical spectrum of the core of NGC 1614. Consistent solutions for the starburst characteristics (star-formation rate, IMF, burst age, morphology) are found and the role of each observational constraint in deriving satisfactory models is extensively discussed. The acceptable contamination of the K band light by the underlying population amounts ≥ 15% even through a 5 arcsec aperture. The model leads to a limit on the direct absorption of Lyman continuum photons by dust situated inside the ionised areas, which in turn, with standard gas-to-dust ratios, translates into small characteristic sizes for the individual coexisting H II regions of the massive starburst area (clusters containing ∼ 102 ionising stars). We show that room is left for IMFs extending to 120 M⊙, rather than truncated at ∼ 60 M⊙ as most conservative studies conclude. High internal velocity dispersions (≥ 20 km s−1) are then needed for the H II regions. An original feature of this work is to base the analysis of near-infrared spectral galaxy observations on a large wavelength range, using models constructed with spectral stellar data observed with the same instrument. However a broader use of this spectral evolution model on other spectral or photometric data samples is possible if the spectral resolution of the model is adapted to observations or if colours are derived from the energy distributions.Catherine J. Cesarsky  相似文献   

3.
We present monitoring analysis of 8 XMM‐Newton observations of the Seyfert 2 galaxy Mrk 3, spanning a period of ∼19 months. The continuum flux in the 3–12 keV band remains constant during this observing period. The X‐ray spectrum is well described, in agreement with previous works, by a highly absorbed (N H > 1024 cm–2) power law model, with a photon index Γ = 1.9 and a strong reflection component. A strong Fe Kα line at 6.4 keV with an equivalent width of ∼500 eV is detected in the X‐ray spectrum. When we consider the co‐added spectrum we also detect a weaker emission line at 7.4 keV corresponding to neutral Ni Kα emission and weak evidence for the presence of an ionized Fe Kα line at 6.7 keV. Direct comparison with the results obtained from an earlier XMM‐Newton observation of Mrk 3, shows a decrease in the continuum flux of ∼30 per cent followed by a similar decrease in the reflected component. Both emission line components at 6.4 and 6.7 keV do not vary. However we find that an alternative model where the N H varies by 20 per cent is also plausible. In this case both the continuum and the reflected emission do not change. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

4.
Photographic observations of the mean H and K profiles are given for several positions across the solar disk (0.1 < < 0.6). The core profiles of H and K are nearly identical at the same position on the sun.Estimates of the mean Doppler width and the depth of formation of the K2 emission peaks are given. A more elaborate analysis confirms that the K2 peaks are formed in a relatively shallow layer ( 0 3) in which the Doppler width decreases rapidly inward. The relevance of these conclusions to current attempts to predict theoretically the H and K profiles is discussed.  相似文献   

5.
Although the Ca ii K232 network is known to be cospatial with magnetic elements there has been doubt as to the magnetic origin of the fainter K2V points. We demonstrate that weak magnetic elements also lie at the roots of the K2V points, and because the latter are numerous they may contribute sensibly to the integrated light profile of Ca ii K.Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.  相似文献   

6.
In this paper we present and analyze new data on the cores of the H and K lines of ionized calcium in the spectrum of integrated sunlight. The intensities of the components H 2v , H3, H 2r , K 2v , K3, and K 2r in the line cores were measured in terms of the continuum intensity at 4000 Å during a solar rotation in September 1969. Other data on these components, obtained at or close to the times of solar minimum (September 1964) and solar maximum (September 1968), were also included. The intensities of these features are compared with two indices of solar activity: the Ca ii plage index and the 2800 MHZ signal. The average correlation coefficients between the intensities of the measured features and those indices were 0.69 and 0.64, respectively. Our results are consistent with those of Bumba and Riková-Topolová (1967) for a solar rotation period in 1965.The method and results should provide a detailed quantitative basis for the study of the activity cycles and rotation periods of solar-type stars.First Weather Wing, Hickman Air Force Base, HI 96824, U.S.A.  相似文献   

7.
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   

8.
Excitation temperatures of the peculiar objects Boss 1985, AG Pegasi and AG Carinae have been derived form the corrected intensities of the emission lines.The values obtained are 5900K for Boss 1985, 8000K for AG Pegasi and 10500K for AG Carinae.From the observed quantities log (I/I c), whereI is the intensity of the line andI c the intensity of the underlying continuum, the true continuum has been derived.The results are in good agreement with those predicted in previous investigations.  相似文献   

9.
We consider the contribution of microlensing to the AGN Fe Kα line and X‐ray continuum amplification and variation. To investigate the variability of the line and X‐ray continuum, we studied the effects of microlensing on quasar X‐ray spectra produced by crossing of a microlensing pattern across a standard relativistic accretion disk. To describe the disk emission we used a ray tracing method considering both metrics, Schwarzschild and Kerr. We found that the Fe Kα and continuum may experience significant amplification by a microlensing event (even for microlenses of very small mass). Also, we investigate a contribution of microlensing to the X‐ray variability of high‐redshifted QSOs, finding that cosmologically distributed deflector may contribute significantly to the X‐ray variability of high‐redshifted QSOs (z > 2). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

10.
Using slab model atmospheres that are irradiated from both sides by photospheric, chromospheric, and coronal radiation fields we have determined the ionization and excitation equilibrium for hydrogen.The model atom consists of two bound levels (n = 1 and n = 2) and a continuum. Ly- was assumed to be optically thick with the transition in detailed radiative balance. The Balmer continuum was assumed to be optically thin with the associated radiative ionization dominated by the photospheric radiation field (T rad = 5940 K). The ionization equilibrium was determined from an exact treatment of the radiative transfer problem for the internally generated Ly-c field and the impressed chromospheric and coronal field (characterized by T rad = 6500K).Our calculations corroborate the hypothesis that N2, the n = 2 population density, is uniquely determined by the electron density N e. We also present ionization curves for 6000K, 7500K, and 10000K models ranging in total hydrogen density from 1 × 1010/cm3 to 3 × 1012/cm3. Using these curves it is possible to obtain the total hydrogen density from the n = 2 population density in prominences and spicules.The National Center for Atmospheric Research is sponsored by the National Science Foundation.  相似文献   

11.
Photographs of the corona in the continuum spectrum (580–700 nm) have been obtained with a doublet camera (F=4m) through rotating sector polarizers with the vibrational directions oriented radially and tangentially to the solar limb. Isophotes of the total emission and its polarized component, as well as diagrams giving the degree of polarization for the (K+F)-corona and the electron corona proper (P K), have been plotted up to the distance of 1R from the limb. In some inner regions the polarizationP K exceeds the highest value possible for Thomson scattering under the given conditions. The reality of this anomally is dubious; systematic photometrical errors may account for it. Three-dimensional forms of 15 different coronal rays have been ascertained by comparing the course of polarization along the rays to the family of Baumach curves. The rays are found to deflect substantially from the radial directions out of the plane of the sky. Mean values of the coronal brightness and polarization versus the distance from the Sun have been determined. Contrary to well-known models (Van de Hulst) the mean polarization of the electron corona (P K) decreases with distance after reaching the maximum (50%) at (1.4–1.6)R from the Sun's centre. This decrease can be explained by deflection of the streamers from radial directions.  相似文献   

12.
An analysis of the spectral distribution of intensity of the Hei recombination continuum is probably the only direct method for determination of the electron temperature of helium emission regions on the Sun. On the basis of data on the Hei Lyman continuum, obtained by Dupree and Reeves from OSO-4, the electron temperature of undisturbed helium regions is determined: T e = = 12500 K. Such a low T e value is a serious argument in favour of the predominant role of UV coronal radiation in the helium ionization on the Sun. Comparison of the Hei Lyman continuum data with results of observations of the 10830 line showed that the visible helium lines and Hei Lyman continuum are produced within the same regions of the undisturbed solar atmosphere at T e = 12500 K.  相似文献   

13.
Two independent sets of high resolution time series spectra of the CaII H and K emission obtained at the Solar Tower and at the Big Dome of the Sacramento Peak Observatory on September 11th, 1971 are reported. The evolutionary behaviour of the emission first reported by Wilson and Evans is confirmed but the detail of the evolution is found to be more complex. In one case, a doubly peaked feature showing some K3 emission evolves into a single K2 (red) peak with no K3 emission. Coincidentally, a neighbouring doubly peaked feature evolves to a very strong blue peak. In an entirely independent sequence a doubly peaked feature evolves into a single red peak. The K2 emission then fades completely although the continuum threads are still strong. Finally a strong K2 blue peak appears. These developments are confirmed by intensity profiles obtained from the spectra.Image motion during the sequences is measured using slit-jaw photographs and changes in the overall pattern of the spectra. It is found to be less than the size of the individual features, i.e. 1–2.While considering that the evolution can be explained by the relative motion of one feature with respect to another during the sequence, it is shown that it is possible to account for all these examples in this way only by invoking coincidence of a very high order.It is concluded that in these cases the observed evolution of the K2 emission is due to temporal variations in the physical conditions which give rise to them.  相似文献   

14.
The profiles of the resonance lines of Caii have been studied in two large disk flares and in the surrounding plage. In the brightest portions of the flares no self-reversal in the central emission core was detected; self-reversed cores were present in the less bright portions of the flares. We find that as the intensity of the emission core increases the separation of the H2 and K2 peaks decreases monotonically, becoming unobservable at intensities near to 0.90 the local continuum. Possible reasons for the behavior of the H and K lines in flares are considered. It is suggested that the largest density enhancements in flares are found near the strongest magnetic field.  相似文献   

15.
Data on the spectrum and center-to-limb variation of the solar Lyman continuum have been analyzed. They show: (a) The brightness temperature of the Lyman continuum is about 6500 K, but the kinetic temperature, as deduced from the slope of the continuum, lies between 8000 and 9000 K. The difference between the kinetic temperature and the brightness temperature requires that the source function be smaller than the Planck function by a factor of several hundred. (b) The Lyman continuum exhibits slight limb darkening longward of 825 Å, and slight limb brightening shortward of 750 Å. The crossover point varies from equator to pole and with solar activity. (c) The slope d ln I()/d of the Lyman continuum decreases toward the limb, implying that the kinetic temperature increases outward in the region of Lyman continuum formation.Using radiative transfer calculations for a plane-parallel atmosphere in hydrostatic equilibrium, we have derived a homogeneous model of the upper chromosphere that reproduces the main features of the observations. It is characterized by a temperature of 8300 K and a pressure of about 0.15 dyne/cm2 at Lyc = 1, and it has an abrupt temperature rise at a height of 1500 km above the limb. More precise agreement with the observations will require a detailed treatment of the inhomogeneous nature of the upper chromosphere.  相似文献   

16.
We analyzed 15 solar occultations observed by the Cassini UVIS instrument to constrain the density and temperature structure near the exobase of Saturn. We retrieved the density of H2 and thus the temperature at altitudes higher than 1900 km above the 1 bar level by analyzing the ionization continuum of H2 at wavelengths shorter than 804 Å. We find that the exospheric temperature ranges from 370 K to 540 K, with a typical uncertainty of less than 20 K. According to our data the temperature increases with latitude from the equator to the poles by 100–150 K. At similar latitudes, the temperature varies by 20–50 K at different times with no evidence for any systematic diurnal trend so far. Based on our data, the exobase of Saturn is 2700–3000 km above the 1 bar level and the thermal escape parameter near the exobase ranges from 260 to 340, implying that thermal escape from Saturn is firmly in the Jeans regime. The mixing ratio of H2 is close to unity at all altitudes below the exobase. We find that the pressure levels in the thermosphere deviate significantly from a simple spheroid predicted by potential theory. This is consistent with significant meridional temperature variations in the lower thermosphere. A global analysis of the temperature structure at different depths in the atmosphere is required to constrain both the shape and the deposition and redistribution of energy in the upper atmosphere further.  相似文献   

17.
The excitation temperature, colour excess and continuum of Car in the visible and near ultraviolet have been determined from the study of the excitation of the ionized iron emission lines. The excitation temperatures of Feii and [Feii] are about 8000K, value which is very much lower than the mean ionization temperature of the elements in Car.E B-V is about 1m.1; the absolute visual magnitude is presently –10m.5±1m. From the equivalent widths of the emission lines the true continuum between 1.5 and 3.0 –1 has been derived. The correspondingB-V is –0m.14, while the Balmer jump is less than 0m.5. The continuum appears mainly nebular in origin with a strong contribution of the two-photon emission from the 2s-level of hydrogen in the blue.  相似文献   

18.
We investigate numerically the chemodynamical evolution of major disc–disc galaxy mergers in order to explore the origin of the mass-dependent chemical, photometric and spectroscopic properties observed in elliptical galaxies. We investigate especially the dependence of the fundamental properties on merger progenitor disc mass (M d). Three main results are obtained in this study:– More massive (luminous) ellipticals formed by galaxy mergers between more massive spirals have higher metallicity (Z) and thus show redder colours; the typical metallicity ranges from ∼ 1.0 solar abundance (Z∼ 0.02) for ellipticals formed by mergers with M d = 1010 M ⊙to ∼ 2.0 solar (Z∼ 0.04) for those with M d= 1012 M ⊙.– Both the Mg2 line index in the central part of ellipticals (R ≤ 0.1 R e) and the radial gradient of Mg2 (δ Mg2 / δ log R) are more likely to be larger for massive ellipticals. δ Mg2 / δ log R correlates reasonably well with the central Mg2 in ellipticals. For most of the present merger models, ellipticals show a positive radial gradient of the Hβ line index. – Both M/L B and M/L K (where M, L B, and L K are the total stellar mass of galaxy mergers, the B-band and the K-band luminosities, respectively) depend on galactic mass in such a way that more massive ellipticals have larger M/L B and smaller M/L K. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

19.
Data with the 2MASS prototype camera were obtained in a 2.3 sq. deg region in Taurus containing Heiles Cloud 2, a region known from IRAS observations to contain a number of very young solar type stars. Data at 1.25 (J), 1.65 (H), and 2.2 (K s )µm are presented. These data are representative of the type and quality of data expected from the planned near-IR surveys, 2MASS and DENIS. Near-IR surveys will be useful for determining the large scale variation of extinction with clouds, for determining the luminosity function in nearby clouds down to ranges of 0.1–1.0 L, and for finding highly extincted T Tauri stars missed by IRAS because the bulk of their luminosity is emitted shortward of 12µm.  相似文献   

20.
A method for obtaining the source function and value of r 0 k c/k L,0 from the variation of equivalent width across the solar disk has been applied to several infrared Fraunhofer lines. The results indicate that most of the lines investigated have non-L.T.E. source functions which are less than or equal to the mean continuum intensity. De Jager and Neven (1968) appear to have underestimated the departures from L.T.E. in a number of cases.  相似文献   

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