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1.
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   

2.
Moderate dispersion (46 Å mm–1 at H) image-tube spectrum (5800–7300 Å) of the S star 1 Gru is found to exhibit several unidentified molecular features, in addition to the well-known bands of the oxides ofs-process elements. A list is presented of 28 measured unidentified red-degraded bands, of which six, at 5998, 6128, 6143, 6223, 6257, and 6557 Å, are prominent. Of the reported 28 bands, 22 are observed for the first time. A discussion is included on the expected molecular sources of the unidentified features. The possible presence of two new molecules, Pr O and Nd O, in 1 Gru is suggested.This paper is dedicated to the memory of Dr. M. K. V. Bappu.  相似文献   

3.
New spectral observations of chemically peculiar (CP) magnetic stars were obtained using an NES echelle spectrometer with a BTA telescope in the Special Astrophysical Observatory (Russian Academy of Sciences). Several stars were shown to have anomalous Li abundances. Testing and monitoring the stars with Doppler shifts Vsini > 10 km/s indicated that the lithium 6708 Å line was variable in the spectra of some roaAP-CP stars. To distinguish variable features in the spectra, the dispersogram technique was used. The most peculiar among the stars studied is HD 12098. The strong and variable lithium 6708 Å line was detected in the spectrum of this star. The star has been shown to have greatly different lithium abundances in two rotation phases corresponding to opposite surface areas. As mentioned earlier, a similar behavior of the Li blend was found in the spectra of HD 83368 and HD 60435 which have lithium spots on their surface. Spectral observations of slowly rotating CP stars with the Doppler shifts Vsini < 10 km/s revealed the strong and nonvariable lithium 6708 Å line in the spectra of these stars. Quantitative spectral analysis using the Li I 6708 Å resonance doublet and the Li I 6103 Å line shows the lithium abundance, as determined by the 6103 Å line, to be somewhat greater than that determined by the 6708 Å line. A higher ratio of 6Li/7Li amounting to ～0.3–0.5 was found in these stars. 6Li production is assumed to be due to spallation reactions on the surface of magnetic CP stars; this isotope ratio remained in strong magnetic fields.  相似文献   

4.
The total radiative output in the EUV continuum (1400–1960 Å) from the 5 September 1973 flare has been obtained from the EUV spectra of the flare observed with the NRL slit spectrograph (SO82B) on Skylab. The radiative energy in the EUV continuum is of the order of 1029 ergs, which is more than a factor of 2 greater than those radiated in soft X-rays (8–20 Å) and in H for the flare. Thus, the EUV continuum emission is an important radiative energy loss, and should be included in the consideration of the energy balance of the flare.Ball Corporation.Now at the Institute of Theoretical Astrophysics, University of Oslo, Oslo, Norway.  相似文献   

5.
Axial rotation of a star plays an important role in its evolution, physical conditions in its atmosphere and the appearance of its spectrum. We analyzed CCD spectra of nine stars for which the projected rotational velocity derived from the Ca II line at λ 3933 Å was remarkably lower than the one derived from the MgII line at λ 4481 Å. We derived effective temperatures and surface gravities using published uvbyβ photometries, and computed synthetic spectra. Comparing the observed line profiles of the two lines with the computed ones, we estimated the values of v sin i. One of the stars, HD44783, is a Be-star which, besides the narrow absorptions in the spectrum originating in its circumstellar envelope, also has lines of interstellar origin. We also found indications of circumstellar matter in the spectrum of HD25152. In the spectra of the remaining seven stars the narrow components in the Ca II λ 3933 Å line as well as narrow absorptions in the Na I λ 5889.951 Å (D1) and λ 5895.924 Å (D2) lines are of interstellar origin. In HD114376 there are two systems of interstellar components, thus disclosing two different interstellar clouds in the direction of the star. In the spectrum of HD138527 signs of a possible companion were detected, the emission of which contributes 15% to the total light of the system.  相似文献   

6.
O vi ( = 1032 Å) profiles have been measured in and above a filament at the limb, previously analyzed in H i, Mg ii, Ca ii resonance lines (Vial et al., 1979). They are compared to profiles measured at the quiet Sun center and at the quiet Sun limb.Absolute intensities are found to be about 1.55 times larger than above the quiet limb at the same height (3); at the top of the prominence (15 above the limb) one finds a maximum blue shift and a minimum line width. The inferred non-thermal velocity (29 km s–1) is about the same as in cooler lines while the approaching line-of-sight velocity (8 km s–1) is lower than in Ca ii lines.The O vi profile recorded 30 above the limb outside the filament is wider (FWHM = 0.33 Å). It can be interpreted as a coronal emission of O vi ions with a temperature of about 106 K, and a non-thermal velocity (NTV) of 49 km s–1. This NTV is twice the NTV of quiet Sun center O vi profiles. Lower NTV require higher temperatures and densities (as suggested by K-coronameter measurements). Computed emission measures for this high temperature regime agree with determinations from disk intensities of euv lines.  相似文献   

7.
The role of T50 in classifying gamma-ray bursts (GRBs) is investigated. We take T50=0.7s as the line of division and find that some bursts belonging to the class of long bursts defined by T90≥2s now become short bursts (sample 1), while some belonging to the class of short bursts defined by T90 < 2 s now become long bursts (sample 2). We study how these sources are affected by the two methods of classification and find the change of classes of sample 1 is due to some peculiar properties of the light curves. Based on their characters, most of the bursts of sample 1 should be taken as short bursts.  相似文献   

8.
Further exploration of the -field theory as first proposed by Yu (1989) is here presented to cover the equation of motion of a test particle which induces gravitational radiation. The same theory is shown to contain an exact gravitational radiation equation derived as a logical consequence of field equations without extra postulates. In this general dynamic context the theory is renamed The (,A µ )-field Theory.  相似文献   

9.
The accuracy of the approximate replacement of the frequency meanj() of the total intensityJ () byJ c+a{J 0()–J c} by Geovenelli, whereJ c is the total intensity at the continuum,J 0() is that at the line center anda is independent of depth, is studied. Numerical calculations for strong solar lines show very high values of the residual intensities. A slight change in the approximation is then suggested to get a result quite consistent with observational and existing calculated data.  相似文献   

10.
We present the first-look analysis of the high-speed multicolour photometry of the bright V361 Hya-type star EO?Ceti (m V=12.3). The observations were gathered with the three-channel ULTRACAM instrument attached to the 4.2-m William Herschel Telescope. The data set has a total time span of 6.2?d and consists of 31 h simultaneous three colour photometry. The main power regions in all three colours are the same as previously reported in the white light photometric campaigns on EO?Ceti. We calculate the frequencies, amplitudes and phases of the significant modes in three colours of the SDSS system, r′, g′ and u′. The amplitudes of the detected modes are the highest in the u′ lightcurve, and the phases are the same in all three colours within the measurement accuracy. The amplitudes of the highest signal-to-noise modes show time variability in all three colours. We analyse the amplitude and phase variations of the five highest signal-to-noise modes in different colours. Even though the amplitudes show variations from night to night, the amplitude ratios are found to be constant to within 2σ level. This result is promising as it allows us to compare the observed amplitude ratios with theoretically calculated amplitude ratios. This may further constrain the mode identification of the highest amplitude modes in EO?Ceti and let us test the proposed seismic and binary evolution models.  相似文献   

11.
We present evidence for a correlation between features observed in simultaneous infrared (8 to 14 μm) and ultraviolet (0.36 μm) images obtained during Venus' 1975 and 1977 apparitions. The sense of the observed correlation is such that bright uv markings correspond to bright (warm) ir features, and similarly, dark uv markings correspond to dark (cool) ir features.  相似文献   

12.
Absorption lines of some actinides, namely, actinium (Z = 89), protactinium (91), neptunium (93), plutonium (94), americium (95), curium (96), berkelium (97), californium (98), and einsteinium (99), were identified in the spectrum of one of the most peculiar main-sequence stars HD 101065 (Przybylski’s star). In the identification we used a high-resolution spectrum (R = 80 000) acquired at the 8.2-m ESO telescope.  相似文献   

13.
From the characteristic actions (s), we can derive various relations between the basic characteristic quantities of objects and the fundamental constants in known physical laws. The main physical processes which lead to the formation of objects should be included in some such reletions through the fundamental constants. The problem of the origin of galaxies has been considered on the basis of the theory of actions (s). It has been shown that in addition to gravitational effect, the dissipation process of the adiabatic density perturbations arising from the Thomson scattering in the early universe is a crucial process in forming galaxies; and if the Hubble constant has a valueH 0 50 km s–1 Mpc–1, the protogalaxies might be formed just before recombination.  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 peculiar δ Del-variable ? Puppis (F6IIp) has been analysed on nine UV high-resolution spectra in the region of Mgii h- and k-lines. This analysis has shown: (1) The Mgii emission is present during the whole pulsation period and increases with increasing luminosity. Maximum emission fluxes seem to occur at phases 0.96–0.12. (2) The phase shift between intensity maxima of Caii and Mgii chromospheric emissions is probably about 0.26. Moreover, it seems that the phase shift between ? Pup and the Cepheid β Dor is longer for the Mgii emission (～0.44) than for the Caii one (～0.27). (3) Violet-red asymmetries are present in emission components. Moreover, the violet component K1V has always an intensity higher than the red one K1R. (4) The averaged radial velocity (RV) curve obtained from three metallic lines is in agreement with that obtained in the optical region. The RV curves of red emission and absorption components are rather similar to that of the metallic lines. Near the minimum of this RV curve, the chromospheric emissions show an intensity enhancement with a negative phase shift similar to that of light curve (～?30 deg). (5) A model with an emitting extended atmosphere around the star is proposed to explain an emission like feature in the self-reversed absorption component K3 and in K1.  相似文献   

16.
It is surprising that we hardly know only 4% of the universe. Rest of the universe is made up of 73% of dark-energy and 23% of dark-matter. Dark-energy is responsible for acceleration of the expanding universe; whereas dark-matter is said to be necessary as extra-mass of bizarre-properties to explain the anomalous rotational-velocity of galaxy. Though the existence of dark-energy has gradually been accepted in scientific community, but the candidates for dark-matter have not been found as yet and are too crazy to be accepted. Thus, it is obvious to look for an alternative theory in place of dark-matter. Milgrom (Astrophys. J. 270:365, 1983a; 270:371, 1983b) has suggested a ‘Modified Newtonian Dynamics (MOND)’ which appears to be highly successful for explaining the anomalous rotational-velocity. But unfortunately MOND lacks theoretical support. The MOND, in-fact, is (empirical) modification of Newtonian-Dynamics through modification in the kinematical acceleration term ‘a’ (which is normally taken as a=\fracv2ra=\frac{v^{2}}{r}) as effective kinematic acceleration aeffective = a m(\fracaa0)a_{\mathit{effective}} = a \mu(\frac{a}{a_{0}}), wherein the μ-function is 1 for usual-values of accelerations but equals to \fracaa0 ( << 1)\frac{a}{a_{0}} (\ll1) if the acceleration ‘a’ is extremely-low lower than a critical value a 0(10−10 m/s2). In the present paper, a novel variant of MOND is proposed with theoretical backing; wherein with the consideration of universe’s acceleration a d due to dark-energy, a new type of μ-function on theoretical-basis emerges out leading to aeffective = a(1 -K \fraca0a)a_{\mathit{effective}} = a(1 -K \frac{a_{0}}{a}). The proposed theoretical-MOND model too is able to fairly explain ‘qualitatively’ the more-or-less ‘flat’ velocity-curve of galaxy-rotation, and is also able to predict a dip (minimum) on the curve.  相似文献   

17.
Braun  D.C.  Lindsey  C. 《Solar physics》2000,192(1-2):285-305
The development of solar acoustic holography has opened a major new diagnostic avenue in local helioseismology. It has revealed `acoustic moats' surrounding sunspots, `acoustic glories' surrounding complex active regions, and `acoustic condensations' suggesting the existence of significant seismic anomalies up to 20 Mm beneath active-region photospheres. Phase-sensitive seismic holography is now yielding high-resolution maps of sound travel-time anomalies caused by magnetic forces in the immediate subphotosphere, apparent thermal enhancements in acoustic moats, and Doppler signatures of subsurface flows. It has given us the first seismic images of a solar flare, and has uncovered a remarkable anomaly in the statistical distribution of seismic emission from acoustic glories. Seismic holography will probably give us the means for early detection of large active regions on the far-surface of the Sun, and possibly of deep subsurface activity as well. This powerful diagnostic now promises a new insight into the hydromechanical and thermal environments of the solar interior in the local perspective.  相似文献   

18.
Priest  E.R.  Schrijver  C.J. 《Solar physics》1999,190(1-2):1-24
In this review paper we discuss several aspects of magnetic reconnection theory, focusing on the field-line motions that are associated with reconnection. A new exact solution of the nonlinear MHD equations for reconnective annihilation is presented which represents a two-fold generalization of the previous solutions. Magnetic reconnection at null points by several mechanisms is summarized, including spine reconnection, fan reconnection and separator reconnection, where it is pointed out that two common features of separator reconnection are the rapid flipping of magnetic field lines and the collapse of the separator to a current sheet. In addition, a formula for the rate of reconnection between two flux tubes is derived. The magnetic field of the corona is highly complex, since the magnetic carpet consists of a multitude of sources in the photosphere. Progress in understanding this complexity may, however, be made by constructing the skeleton of the field and developing a theory for the local and global bifurcations between the different topologies. The eruption of flux from the Sun may even sometimes be due to a change of topology caused by emerging flux break-out. A CD-ROM attached to this paper presents the results of a toy model of vacuum reconnection, which suggests that rapid flipping of field lines in fan and separator reconnection is an essential ingredient also in real non-vacuum conditions. In addition, it gives an example of binary reconnection between a pair of unbalanced sources as they move around, which may contribute significantly to coronal heating. Finally, we present examples in TRACE movies of geometrical changes of the coronal magnetic field that are a likely result of large-scale magnetic reconnection. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1005248007615  相似文献   

19.
Turova  I.P.  Grigoryeva  S.A. 《Solar physics》2000,197(1):43-56
The ratios I(K 1)/I(H 1) and I(K 3)/I(H 3) were calculated from four semi-empirical models of sunspot umbra. We determined the dependencies of both ratios of such parameters as temperature gradient and atmospheric opacity. A certain influence on the expected ratios I(K 1)/I(H 1) and I(K 3)/I(H 3) can also come from the FIP effect provided it exists in the chromosphere above sunspot umbra. Theoretical and observed values of I(K 1)/I(H 1) and I(K 3)/I(H 3) are compared. It is shown that for one of the sunspots we observed, the values obtained for the ratio I(K 1)/I(H 1) cannot be explained in terms of existing umbra models.  相似文献   

20.
The implications of the intrinsic luminosity evolution with cosmological epoch on the value of the density parameter () and evolution of radio sizes of extragalactic radio sources have been considered. It is shown that a power law evolution model of the sortP (1 +z) can be used to contrain the value of . In the presence of a strong luminosity evolution, the model yields an upper limit of 0.5.It is also shown that the angular diameter redshift ( – z) relation for quasars can be interpreted in terms of the assumed luminosity evolution combined with a luminosity-linear size correlation with little or no linear size evolution required. On the other hand, strong linear size evolution is needed to explain the – z data for radio galaxies independent of luminosity.  相似文献   

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