用氧-18研究秦皇岛市燕塞湖水资源组成   总被引：1，自引：0，他引：1  

高文义 《地球科学与环境学报》1993,(Z2)

进入燕塞湖的水,由大气降水和地下水组成,δ~(18)O测定结果表明:沿大石河地下水δ~(18)O变化在-8.361‰至-7.915‰之间;大气降水δ~(18)O值明显低于地下水δ~(18)O值;伴随河水起涨到消退,河水δ~(18)O值由大变小。  相似文献   

Observations of the gamma-ray flux from the X-ray source Cyg X-3 in 1994–1995     

Yu. I. Neshpor  O. R. Kalekin  A. A. Stepanian  V. P. Fomin  N. N. Chalenko 《Astronomy Letters》2003,29(4):236-240

We present the observations of Cygnus X-3 carried out with the GT-48 gamma-ray telescope at the Crimean Astrophysical Observatory in 1994–1995. The mean gamma-ray flux at energy E>10¹² eV is shown to be approximately equal to 1.3×10^?11 cm^?2 s^?1. The flux in 1994 was much lower than that in 1995, being (6.2±2.6)×10^?12 cm^?2 s^?1; i.e., it was statistically insignificant. The flux in 1995 was (2.7±0.7)×10^?11 cm^?2 s^?1. Thus, the very high energy gamma-ray emission from Cyg X-3 is variable. These measurement results can be used to obtain upper limits on the flux from Cyg X-3 in 1994–1995.  相似文献   

On the mechanism of X-ray emission from radio pulsars     

I. F. Malov 《Astronomy Letters》2003,29(8):502-509

We discuss the correlations between the luminosities of radio pulsars in various frequency ranges and the magnetic fields on the light cylinder. These correlations suggest that the observed emission is generated in outer layers of the pulsar magnetospheres by the synchrotron mechanism. To calculate the distribution functions of the relativistic particles in the generation region, we use a model of quasilinear interactions between the waves excited by cyclotron instability and particles of the primary beam and the secondary electron—positron plasma. We derive a formula for calculating the X-ray luminosity L _x of radio pulsars. A strong correlation was found between L _x and the parameter \(\dot P_{ - 15} /P^{3.5}\), where P is the neutron-star rotation period, in close agreement with this formula. The latter makes it possible to predict the detection of X-ray emission from more than a hundred (114) known radio pulsars. We show that the Lorentz factors of the secondary particles are small (γ _p = 1.5–8.5), implying that the magnetic field near the neutron-star surface in these objects is multipolar. It follows from our model that almost all of the millisecond pulsars must emit X-ray synchrotron radiation. This conclusion differs from predictions of other models and can be used to test the theory under consideration. The list of potential X-ray radiators presented here can be used to search for X-ray sources with existing instruments.  相似文献   

Continental impact on marine boundary layer coarse particles over the Atlantic Ocean between Europe and Antarctica     

Jarkko V. Niemi  Heikki Tervahattu  Aki Virkkula  Risto Hillamo  Kimmo Teinil  Ismo K. Koponen  Markku Kulmala 《Atmospheric Research》2005,75(4):109

Aerosol samples were collected in the Atlantic marine boundary layer between the English Channel and Antarctica during November–December 1999. The composition of coarse (aerodynamic diameter 1–3 μm) individual aerosol particles was studied using the SEM/EDX method. The major particle types observed were fresh sea salt, sea-salt particles reacted partly or totally with sulphuric acid or nitric acid, Mg-sulphate, Ca-sulphate, mixed aluminosilicates and sea salt, aluminosilicates, Ca-rich particles and Fe-rich particles. The relative fractions of sea-salt particles with moderate or strong Cl depletion were high near the coasts of Europe (65–74%) and Northern Africa (44–87%), low far from the coast of Western Africa (10–20%) and very low in remote sea areas between Africa and Antarctica (1%). The Cl depletion was strongest when air masses arrived from the direction of anthropogenic pollution sources. The fractions of Mg-sulphate particles were high (18–25%) in 2 samples near Europe. The Mg-sulphate particles were probably formed as a result of fractional recrystallization of sea-salt particles in which Cl was substituted by sulphate. It remained unclear whether these particles were formed in the atmosphere or during and after sampling. The relative fractions of particles from continental sources were quite low (10–15%) near Europe, very high (25–78%) near the coast of Northwestern Africa and very low in the remote sea areas (0–2%). Most of the continental particles were aluminosilicates and some of them were internally mixed with sea salt. Near the coast of Northwestern Africa, the main source of aluminosilicates was Saharan dust, and near the Gulf of Guinea, emissions from biomass burning were also mixed with aluminosilicates and sea salt.  相似文献   

Long-term monitoring of the long-period variable Y Cassiopeiae in the 1.35-cm water-vapor line     

G. M. Rudnitskii  M. I. Pashchenko 《Astronomy Letters》2005,31(11):760-766

Observations of the circumstellar maser emission from the long-period variable star Y Cas in the 1.35-cm water-vapor line are presented. The observations were performed with the RT-22 radio telescope at the Pushchino Radio Astronomy Observatory (Astrospace Center, Lebedev Physical Institute, Russian Academy of Sciences) in the period 1982–2005. The variations in the integrated flux F_int in the H₂O line correlate with the visual light curve of the star. The phase delay Δ? between the F_int variations and the light curve is 0.2–0.4P (P is the period of the star). The H₂O maser Y Cas belongs to transient sources: peaks of high maser activity alternate with intervals of a low emission level when the H₂O-line flux does not exceed (0.1–0.5) × 10^?20 W m^?2. A “superperiod” of ～5.7 yr was found in the occurrence of activity peaks. A particularly strong maximum of maser radio emission took place at the end of 1997, when the flux F_int reached 15.6 × 10^?20 W m^?2. A model for the H₂O maser variability in Y Cas is discussed. The variability is caused by a periodic action of shock waves driven by stellar pulsations. The H₂O maser flares may be associated with short-lived episodes of enhanced mass loss by the star or with the propagation of a particularly strong shock wave when a planet orbiting the star passes through its periastron.  相似文献   

Effects of dense medium surrounding galactic-sized radio sources     

Everton Lüdke 《Astrophysics and Space Science》1994,216(1-2):369-370

In this paper, I have analysed the subarcsecond polarization structure of two high-z compact steep-spectrum quasars. Morphology suggests that the jets are interacting strongly with intergalactic medium. Models of bending by ram pressure equilibrium in a cooling flow and alignment of magnetic field lines by jet-IGM shock suggest that the CSS jets are light, supersonic and mildly relativistic. Particle energy index variations along the jet suggests replenishment triggered by such interactions.  相似文献   

Choosing the 'best' double couple from a moment-tensor inversion     

R. A. Strelitz 《Geophysical Journal International》1989,99(3):811-815

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Distribution of quasars on the sky     

Halton Arp 《Journal of Astrophysics and Astronomy》1984,5(1):31-41

It is shown that high-redshift quasars of bright apparent magnitude are concentrated in the direction of the centre of the Local Group of galaxies. A number of them are distributed along a line originating from the Local Group companion galaxy, M 33. A similar, but shorter and fainter line of quasars is seen emanating from the spiral galaxy NGC 300 in the next nearest, Sculptor Group of galaxies. The concentration of bright quasars in the Local Group direction is supported by bright radio sources catalogued in high-frequency surveys. One of the consequences of this large-scale inhomogeneity is to explain the different gradient of radio source counts in the direction of the Local Supercluster, a result discovered in 1978 but never investigated further. Previously reported homogeneity and isotropy of radio-source counts over the sky would seem to be an effect of integrating nearby, large-scale groupings with more distant, smaller-scale groupings over different directions in the sky. More careful analyses as a function of flux strength and spectral index on various scales over the sky are now required. Previous conclusions about radio source and quasar luminosity and number evolution drawn from logN- logS counts would then need to be re-evaluated.  相似文献   

Two years of observations of the X-ray pulsar SMC X-1 with the ART-P telescope onboard the Granat observatory     

A. A. Lutovinov  S. S. Tsygankov  S. A. Grebenev  M. N. Pavlinsky  R. A. Sunyaev 《Astronomy Letters》2004,30(1):50-57

We present the observations of the pulsar SMC X-1 with the ART-P telescope onboard the Granat observatory. We investigate the variability of the flux from the source on time scales of several tens of days. The intensity variation of the pulsar are shown to be consistent with the presence of a periodicity in the system with a characteristic time scale of ～61 days. The precession of an inclined accretion disk, as indirectly confirmed by the absence of low-state pulsations, may be responsible for the observed variability. The spectrum of the source is well described by a power-law energy dependence of the photon flux density with a slope of ～1.5 and an exponential cutoff at energies above ～14–18 keV. We estimated the inclinations between the planes of the orbit and the accretion disk and the magnetic field of the neutron star.  相似文献   

A hard X-ray survey of the Galactic-Center region with the IBIS telescope of the INTEGRAL observatory: A catalog of sources     

M. G. Revnivtsev  R. A. Sunyaev  D. A. Varshalovich  V. V. Zheleznyakov  A. M. Cherepashchuk  A. A. Lutovinov  E. M. Churazov  S. A. Grebenev  M. R. Gilfanov 《Astronomy Letters》2004,30(6):382-389

From August 23 through September 24, 2003, the INTEGRAL Observatory conducted a deep survey of the Galactic-Center region with a record-breaking sensitivity at energies above 20 keV. We have analyzed the images of the Galactic-Center region obtained with the ISGRI detector of the IBIS telescope (15–200 keV) and give a catalog of detected sources. We detected a total of 60 sources with fluxes above 1.5 mCrab, 44 and 3 of which were previously identified as binary systems of different classes in our Galaxy and as extragalactic objects, respectively. We discovered one new source.  相似文献