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1.
The nature of various components of the W28 complex region is investigated. The radio spectra of W28-A1 (G 6.4-0.2), M20 (G 7.0-0.2), W28-A2 (G 5.9-0.4), W28-A4 (G 5.3-1.1), KE59 (G 6.6-0.3) and G 6.4-0.5 are established over a wide range of frequencies. The W28-A1 (G 6.4-0.2) source is a SNR (sp. index –0.41), the M20, W28-A2 and KE59 seem to be thermal sources (sp. indexes –0.06, –0.15 and –0.04 respectively) whereas the W28-A4 and G 6.4-0.5 are possibly mixed sources containing thermal and non-thermal features. Certain physical parameters of the thermal components are derived by adopting a model. The physical properties of the W28-A1 SNR are investigated. The possibility of a SNR-Hii regions association in the W28 region is also discussed.  相似文献   

2.
D. L. Croom 《Solar physics》1970,15(2):414-423
The results of 2 1/2 years (July 1967 – December 1969) monitoring of solar radio bursts at 71 GHz ( = 4.2 mm) at the Radio and Space Research Station, Slough are presented. During this period only seven events were positively identified as 71 GHz bursts. One of these events (6 July, 1968) is among the largest solar bursts ever recorded anywhere in the microwave-millimetre wave band (47000 × 10–22Wm–2Hz–1), and the associated magnetic field may possibly have exceeded 7200 G. Another event (27 March, 1969) has demonstrated that bursts at 71 GHz can be both intense (4700 × 10–22Wm–2Hz–1) and complex. On other occasions, the absence of any detectable event at 71 GHz helps to define the high frequency spectrum of the burst, this being an important factor in determining the initial energy distribution of the electrons ejected by the associated flare. On one such occasion (21 March, 1969) the derived energy distribution index is 8, in contrast with the more usual values of 2–4.1969–1970 NCR-OAR Senior Post-Doctoral Research Associate at Air Force Cambridge Research Laboratories, L. G. Hanscom Field, Bedford, Mass., U.S.A.  相似文献   

3.
Microwave maps of solar active region NOAA 8365 are used to derive the coronal magnetograms of this region. The technique is based on the fact that the circular polarization of a radio source is modified when microwaves pass through the coronal magnetic field transverse to the line of sight. The observations were taken with the Siberian Solar Radio Telescope (SSRT) on October 21 – 23 and with the Nobeyama Radio Heliograph (NoRH) on October 22 – 24, 1998. The known theory of wave mode coupling in quasi-transverse (QT) region is employed to evaluate the coronal magnetograms in the range of 10 – 30 G at the wavelength 5.2 cm and 50 – 110 G at 1.76 cm, taking the product of electron density and the scale of coronal field divergence to be constant of 1018 cm–2. The height of the QT-region is estimated from the force-free field extrapolations as 6.2 × 109 cm for the 20 G and 2.3 × 109 cm for 85 G levels. We find that on large spatial scale, the coronal magnetograms derived from the radio observations show similarity with the magnetic fields extrapolated from the photosphere.  相似文献   

4.
Yasnov  L.V.  Bogod  V.M.  Fu  Q.  Yan  Y. 《Solar physics》2003,215(2):343-355
Based on spectral observations of active region NOAA 8545 on 19 May 1999, we describe the processes responsible for non-thermal long-lasting radio emission and for narrow-band non-drifting bursts observed at the same time. Non-thermal long-lasting radio emission consisted of two components: short-duration (1–2 s) microbursts with fluxes about 0.001 s.f.u. and continuum emission with growing spectrum in the range of 1000–2000 MHz. Energetic electrons continuously existed in the active region for more than 2.2 hours. The nature and parameters of microbursts were discussed by Bogod, Mercier, and Yasnov (2001). Here we consider the continuum source nature. It is shown that the model, taking into account the cyclotron loss-cone instability of hot electrons and the generation of plasma waves at the upper hybrid frequency, may explain the observed continuum source parameters. For the narrow-band non-drifting bursts we consider two models: the first taking into account an excitation of weak shock waves across the magnetic field and the second with an excitation of the upper hybrid waves under the double plasma resonance. Continuum source parameters are close to the last model. Our estimations for the magnetic field strength are as follows: H=120–126 G, which is valid for the region where the electron density of background plasmas n=(1.4–1.9) ×109 cm–3; H=180–190 G for the region where n=(3.0–4.3) ×109 cm–3; H=290 G for the region where n e=2.5×1010 cm–3; and H=350 G for the region where n e=3.5×1010 cm–3. The speed of the fast electrons is about 0.10–0.14 c.  相似文献   

5.
We have analyzed a Late Holocene record, almost 5000 years long, consisting of varved sediments deposited in the oxygen-minimum zone (OMZ) off Pakistan. We searched for cyclicity in the series of varve thickness (“varve” cycles), of unusually large excursions in varve thickness (“agitation” cycles), and of abundance of turbidites (“turbidite” cycles). We found the following high-frequency cycles (periods between 10 and 100 years) in one or several of the three types of series as follows: near 12.4, 14–15, 16.8, 18.6 (strong, agitation), 25–26 (strong, turbidite), 29–31 (strong, agitation), 39 (varve), 44 (strong, turbidite), 51–54 (strong, agitation), 56 (strong, varve), 64 (strong, turbidite), 69, 77 (strong, turbidite), 82 (very strong, agitation), and 95 years (strong, varve). Low-frequency cycles center around 99–115, 125 (very strong, varve), 164, 177, 202, 242–255 (strong, agitation and turbidite), 280 (strong, varve; doubled, turbidite), 340–370 and 460–490 years.Some cycles of varve thickness match the cyclicity of turbidite frequency (12.3, 14–15, 25–26, 245–255 years) but similarities between spectra are not striking. Taken as a whole, however, the sequence of cycles detected (by autocorrelation and standard Fourier analysis) seems to contain a large proportion of multiples of the basic tidal cycles 4.425 (lunar perigee cycle) and 9.3 years (lunar half-nodal cycle). This impression is supported by testing the three binned spectra for whole-number multiples and fractions as well as whole-number beat structure. We therefore propose that a large proportion of the cyclicity detected can be ascribed to tidal action. Our record also contains evidence for the presence of the 1470-year cycle previously reported from the glacial-age Greenland ice record. The main harmonics of this Greenland cycle can be tied to the pattern of periods seen in the varved sediments. We hypothesize that tidal action produces the cycle, and that the reason for its great length is the requirement that maximum tidal activity has to fall into a narrow seasonal window to be geologically effective.  相似文献   

6.
Chae  Jongchul  Moon  Yong-Jae  Wang  Haimin  Yun  H.S. 《Solar physics》2002,207(1):73-85
Canceling magnetic features are commonly believed to result from magnetic reconnection in the low atmosphere. According to the Sweet–Parker type reconnection model, the rate of flux cancellation in a canceling magnetic feature is related to the converging speed of each pole. To test this prediction observationally, we have analyzed the time variation of two canceling magnetic features in detail using the high-resolution magnetograms taken by the Michelson Doppler Imager (MDI) on the Solar and Heliospheric Observatory (SOHO). As a result, we have obtained the rate and converging speed of flux cancellation in each feature: 1.3×1018 Mx hr–1 (or 1.1×106 G cm s–1 per unit contact length) and 0.35 km s–1 in the smaller one, and 3.5×1018 Mx hr–1 (1.2×106 G cm s–1) and 0.27 km s–1 in the bigger one. The observed speeds are found to be significantly bigger than the theoretically expected ones, but this discrepancy can be resolved if uncertainty factors such as low area filling factor of magnetic flux and low electric conductivity are taken into account.  相似文献   

7.
The light curves, obtained by the authors of the present paper during the period 1978–1992, of the chromospherically active binary system RT Lac were examined. The average (B–V) colour indices were obtained and corrected for the interstellar extinction. Spectroscopic studies indicate that the less massive component may be taken as G8. The light curve analysis indicates that the less massive, larger component fills its corresponding Roche lobe. Both photometric and spectroscopic observations compel one to draw a conclusion that circumstellar matter does exist around the binary system. A colour excess caused by this matter is found to be 0.278 for B–V colour at mid–secondary eclipse. On the basis of photometric colour indices alone, the components of RT Lac are classified as G3–4 and G8. If we use the observed radial velocities of the less massive subgiant star from Ca II emission lines and from other optical lines we find for the mass of the more massive component as 1.34–1.70 M. This mass range corresponds to the main sequence late F stars. The common envelope hypothesis and mass function and also blending of the spectral lines of more massive component point out that it should be at most a late F type main sequence star.  相似文献   

8.
Methylidyne (CH) line observations were obtained at Algonquin from the diffuse molecular cloud envelope at G180.9+4.1, sandwiched between the optical H II region S241 and the molecular cloud core at G180.8+4.0. An analysis of these observations yields several of the envelope parameters, notably a CH column density of 2×1013 cm–2, a microturbulent velocity of 2.6 km s–1, and a total space density of 40 cm–3.  相似文献   

9.
The metal abundance distribution (the metallicity function, MF) of stars and globular clusters is studied. It is found to have three gaps, near [Fe/H]=–1.0, –0.5 and –0.1. The gaps are shown to be statistically significant practically at the 100% confidence level. They divide the galactic population into four metallicity groups with the average [Fe/H] of about –1.5, –0.8, –0.25 and +0.10 (groups I, II, III and IV, respectively). The main contribution into the scatter of metallicity within the groups (apart from group I) comes from random errors in abundance measurements. So we infer that the actual MF must be essentially discrete. These results substantiate the ones obtained in our previous Papers I–IV; they support our idea on active phases in the evolution of the Galaxy, which imply the intermittent enrichment and star formation.We find that the kinematics and metallicity of groups III and IV of F and G dwarfs show a paradox: the metal-rich group (group IV) of G dwarfs turns out to be kinematically older than the group III of F dwarfs with half the metal abundance. The implication of this result for star formation is discussed. Also we show that the portion of metal poor disk population F dwarfs (group III) is the same or even larger than that of G dwarfs. This fact disagrees with the conventional idea that the young kinematics of F dwarfs owes to the absence of old F dwarfs, which are supposed to be evolved into red giants.  相似文献   

10.
Northward flowing coastal currents along the western margin of India during winter–spring advect low-salinity Bay of Bengal water in to the Eastern Arabian Sea producing a distinct low-salinity tongue, the strength of which is largely governed by the freshwater flux to the bay during summer monsoons. Utilizing the sedimentary records of δ18OG. sacculifer, we reconstructed the past salinity-gradient within that low-salinity tongue, which serves as a proxy for the variation in freshwater flux to the Bay of Bengal and hence summer monsoon intensity.The north–south contrast in the sea level corrected (residual)-δ18OG. sacculifer can be interpreted as a measure of surface salinity-contrast between those two locations because the modern sea surface temperature and its past variation in the study region is nearly uniform. The core-top residual-δ18OG. sacculifer contrast of 0.45‰ between the two cores is assumed to reflect the modern surface salinity difference of 1 psu and serves as a calibration for past variations.The residual-δ18OG. sacculifer contrast varies between 0.2‰ at 75 ky B.P. (i.e., late-Marine Isotope Stage 5) and 0.7‰ at 20 ky B.P. (i.e., Last Glacial Maximum), suggesting that the overall salinity difference between the northern- and southern-end of the low-salinity tongue has varied between 0.6 and 1.6 psu. Considerably reduced difference during the former period than the modern suggests substantially intensified and northward-extended low-salinity tongue due to intense summer monsoons than today. On the other hand, larger difference (1.6 psu) during the latter period indicates that the low-salinity tongue was significantly weakened or withdrawn due to weaker summer monsoons. Thus, the salinity-gradient in the eastern Arabian Sea low-salinity tongue can be used to understand the past variations in the Indian summer monsoons.  相似文献   

11.
The ordinary spinor differential Equation (20) of the unperturbed Kepler motion is obtained from the classical equation of motion (19) if one uses the spinor regularization (9) and postulates an essential subsidiary condition (10). A natural generalization for the Kepler motion follows by dropping this subsidiary conditions; it is the 8-parameter set of solutions of the spinor equation of motion (20). The sixteen natural extensive integrals (30)–(35) for this generalized Kepler motion are here deduced by means of the relativistic motors (2), (7) of the Spinor Ring Algebra. These integrals form, with respect to the Poisson bracket operation, a 15-dimensional Lie algebra (40)–(44), closely related to the Lie algebras in quantum mechanics.Dedicated to Professor G. Järnefelt on his 70th anniversary.  相似文献   

12.
In a previous paper Lyttleton (1976) has shown that the apparent secular accelerations of the Sun and Moon, as given by de Sitter, can be largely explained if the Earth is contracting at the rate required by the phase-change hypothesis for the nature of the core. More reliable values for these accelerations have since become available which warrant a redetermination of the various effects concerned on the basis of constantG, and this is first carried out in the present paper. The lunar tidal couple, which is the same whetherG is changing or not, is found to be (4.74±0.38)×1023 cgs, about three-quarters that yielded by the de Sitter values, while within the theory the Moon would take correspondingly longer to reach close proximity to the Earth at about 1.5×109 years ago.The more accurate values of the accelerations enable examination to be made of the effects that a decreasingG would have, and it is shown that a valueG/G=–3×10–11 yr–1 can be weakly satisfied compared with the close agreement found on the basis of constantG, while a value as large numerically asG/G=–6×10–11 yr–1 seems to be definitely ruled out. On the iron-core model, an intrinsic positive component of acceleration of the angular velocity cannot be reconciled at all with the secular accelerations even for constantG, and far less so ifG is decreasing at a rate suggested by any recent cosmological theory.ItG=0, the amount of contraction available for mountain-building would correspond to a reduction of surface area of about 49×106 km2 and a volume to be redistributed of 160×109 km3 if the time of collapse were 2.5×109 years ago. For earlier times, the values are only slightly reduced. IfG/G=–3×10–11 yr–1, the corresponding values are 44×106 km2 and 138×109 km3 for collapse at –2.5×109 yr, and not importantly smaller at 38×106 km2 and 122×109 km3 for collapse at –4.5×109 yr. Any of these values would suffice to account in order of magnitude for all the eras of mountain-building. An intense brief period of mountain-building on an immense scale would result from the Ramsey-collapse at whatever time past it may have occurred.  相似文献   

13.
From investigating spectrograms of penumbrae of some sunspots it is concluded that the maximum magnetic field strength occurs in dark filaments and amounts to 1800–1900 G; the intensity of the magnetic field in dark filaments is 100–400 G larger than in the neighbouring bright filaments; the bright filaments seen in the space between the dark features cannot be attributed to the ordinary undisturbed photosphere.  相似文献   

14.
The SOLAR-A spacecraft has spectroscopic capabilities in a wide energy band from soft X-rays to gamma-rays. The Wide Band Spectrometer (WBS), consisting of three kinds of spectrometers, soft X-ray spectrometer (SXS), hard X-ray spectrometer (HXS) and gamma-ray spectrometer (GRS), is installed on SOLAR-A to investigate plasma heating, high-energy particle acceleration, and interaction processes. SXS has two proportional counters and each counter provides 128-channel pulse height data in the 2–30 keV range every 2 s and 2-channel pulse count data every 0.25 s. HXS has a NaI scintillation detector and provides 32-channel pulse height data in the 20–400 keV range every 1 s and 2-channel pulse count data every 0.125 s. GRS has two identical BGO scintillation detectors and each detector provides 128-channel pulse height data in the 0.2–10 MeV range every 4 s and 4-channel pulse count data (0.2–0.7, 0.7–4, 4–7, and 7–10 MeV) every 0.25–0.5 s. In addition, each of the BGO scintillation detectors provides 16-channel pulse height data in the 8–100 MeV range every 4 s and 2-channel pulse count data (8–30 and 30–100 MeV) every 0.5 s. The SXS observations enable one to study the thermal evolution of flare plasma by obtaining time series of electron temperatures and emission measures of hot plasma; the HXS observations enable one to study the electron acceleration and heating mechanisms by obtaining time series of the electron spectrum; and the GRS observations enable one to study the high-energy electron and ion acceleration and interaction processes by obtaining time series of electron and ion spectra.After the launch the name of SOLAR-A has been changed to YOHKOH.  相似文献   

15.
An ASCA observation of the Jovian impact of the comet Shoemaker-Levy 9 is reported. Four impacts of H, L, Q1 and R were observed and four impacts of B, C, G, and Q2 were observed within 60 minutes after their impacts. No significant flaring of X-ray emission was observed. Upper limit X-ray fluxes of 90 % confidence level, averaged 5 minutes just after the impacts, were 2.4 × 10–13 erg sec–1 cm–2, 3.5 × 10–13 erg sec–1 cm–2, 1.6 × 10–13 erg sec–1 cm–2 and 2.9 × 10–13 erg sec–1 cm–2 for the impacts of H, L, Q1 and R, respectively, in the 0.5(0.7 for H and Q1)–10 keV energy range. However, a hint of X-ray enhancement around Jupiter from July 17 to July 19 was detected with about 2 6 × 10–14 erg sec–1 cm–2 in the 0.5–10 keV energy range.  相似文献   

16.
K. Kai 《Solar physics》1986,104(1):235-241
In attempting to explain observed hard X-ray and microwave flux from solar flares by a single population of energetic electrons, one has met a serious discrepancy of the order of 103–105 between the calculated and observed microwave flux. In this paper it is shown that this discrepancy can be removed for impulsive flares by the assumption of a precipitation model for both X-ray and microwave sources and that the magnetic field of 500–1000 G is required in the microwave emitting region. The precipitation model is consistent with the rapid time variation exhibited in both hard X-rays and microwaves.Proceedings of the Workshop on Radio Continua during Solar Flares, held at Duino (Trieste), Italy, 27–31 May, 1985.  相似文献   

17.
Multi-wavelength photometric observations of Cygnus X-3 were carried out at 18 cm through to 450 μm, complemented by X-ray (2–10 keV) observations. The system was mildly active with cm fluxes at 150–250 mJy. We find the spectrum to be flat with a spectral index of zero. Using a modified Wolf-Rayet wind model, and assuming emission is generated in synchrotron emitting jets from the source, we find an upper-limit to the magnetic field of 20 G at a distance 5×1012 cm is required.  相似文献   

18.
Multiyear high precision measurements of the longitudinal component of the magnetic field (Be) of four supergiants are reported: Aqr (G0 Ib), Aqr (G2 Ib), Gem (G8 Ib), and Peg (K2 Ib). The best measurement accuracy, =0.8 G, was achieved for Peg. A Monte Carlo method was used to test the reliability of the derived measurement errors. The differences between the observational errors and the calculated Monte Carlo errors were 3.2%. For Aqr and Aqr no statistically significant value of the magnetic field was recorded when averaged over a night. For eGem the following overnight average values of the magnetic field were recorded on five nights: 11.1±2.7 G, 9.8±2.5 G, –10.5±3.0 G, 38.1±7.4 G, and 5.3±1.5 G. For Peg the magnetic field recorded over two nights was –5.3±0.9 G and – 2.7±0.8 G.Translated from Astrofizika, Vol. 48, No. 1, pp. 15–28 (February 2005).  相似文献   

19.
Hydrographic changes in the NW Arabian Sea are mainly controlled by the monsoon system. This results in a strong seasonal and vertical gradient in surface water properties, such as temperature, nutrients, carbonate chemistry and the isotopic composition of dissolved inorganic carbon (δ13CDIC). Living specimens of the planktic foraminifer species Globigerina bulloides and Globigerinoides ruber, were collected using depth stratified plankton tows during the SW monsoon upwelling period in August 1992 and the NE monsoon non-upwelling period in March 1993. We compare their distribution and the stable isotope composition to the seawater properties of the two contrasting monsoon seasons. The oxygen isotope composition of the shells (δ18Oshell) and vertical shell concentration profiles indicate that the depth habitat for both species is shallower during upwelling (SW monsoon period) than during non-upwelling (NE monsoon period). The calcification temperatures suggest that most of the calcite is precipitated at a depth level just below the deep chlorophyll maximum (DCM), however above the main thermocline. Consequently, the average calcification temperature of G. ruber and G. bulloides is lower than the sea surface temperature by 1.7±0.8 and 1.3±0.9 °C, respectively. The carbon isotope composition of the shells (δ13Cshell) of both species differs from the in situ δ13CDIC found at the calcification depths of the specimens. The observed offset between the δ13Cshell and the ambient δ13CDIC results from (1) metabolic/ontogenetic effects, (2) the carbonate chemistry of the seawater and, for symbiotic G. ruber, (3) the possible effect of symbionts or symbiont activity. Ontogenetic effects produce size trends in Δδ13Cshell–DIC and Δδ18Oshell–w: large shells of G. bulloides (250–355μm) are 0.33‰ (δ13C) and 0.23‰ (δ18O) higher compared to smaller ones (150–250 μm). For G. ruber, this is 0.39‰ (δ13C) and 0.17‰ (δ18O). Our field study shows that the δ13Cshell decreases as a result of lower δ13CDIC values in upwelled waters, while the effects of the carbonate system and/or temperature act in an opposite direction and increase the δ13Cshell as a result lower [CO32−] (or pH) values and/or lower temperature. The Δδ13Cshell–DIC [CO32−] slopes from our field data are close to those reported literature from laboratory culture experiments. Since seawater carbonate chemistry affects the δ13Cshell in an opposite sense, and often with a larger magnitude, than the change related to productivity (i.e. δ13CDIC), higher δ13Cshell values may be expected during periods of upwelling.  相似文献   

20.
The data of three-times repeated magnetic survey of the section of Lunokhod-2 route 1.5 km long are analyzed. The linear size of the regions of magnetic field anomalies disclosed is 200–300 m. The results of magnetic survey near the tectonic break of Straight Rille and near the south rim of crater Le Monnier were used for estimation of rock magnetization in situ. It is shown that mare basalts in south-east region of crater Le Monnier have oblique magnetization (at the angle ç30° to horizon). The magnitude of magnetization is × 5 × 10–5 G cm g–1. The south-east slope of the crater Le Monnier is magnetized roughly vertically, the upper limit of magnetization of the rocks of the rim is ç 1 × 10–5 G cm3 g–1. The results of an analysis of 160 magnetic field variations recorded by Lunokhod-2 indicate that the horizontal components of variations have nearly linear polarization. The principal axes of hodographs stretch in the direction north-west-south-east. Such a polarization of variations may be due to an increase of the thickness of the upper isolated layer under Mare Serenitatis.  相似文献   

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