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1.
The results of infrared observations of the two Be stars X Per and V725 Tau, which are the optical components of X-ray binary systems, obtained in 1994–2016 are presented. The observations cover Be-star phases as well as shell phases. The data analysis shows that the radiation observed from the binaries at 1.25, 3.5, and 5 μm can be explained as the combined radiation from the optical components and variable sources (shells/disks) that emit as blackbodies (BBs). Emission from a source with the color temperature T c ~1000?1500 K was detected for X Per at λ ≥ 3.5 μm. The highest IR-brightness variation amplitudes for X Per were 0.9?1.2 m (JHK magnitudes) and ~1.45 m (LM magnitudes); for V725 Tau, they were 1.1?1.4 m and ~1.7 m (L magnitudes). The parameters of the optical components and interstellar extinction during the Be phases were estimated: the color excesswasE(B?V) = 0.65±0.08 m and 0.77 ± 0.03 m for X Per and V725 Tau, respectively. Light from the variable sources (disks/shells) was distinguished and their color temperatures, radii, and luminosities estimated for different observation epochs in a BB model. The variations of the binaries’ IR brightness and colors are shown to be due to changing parameters of the variable sources. The mean color temperature of the cool source (disk/shell) and the mean radius and mean luminosity of X Per are 9500± 2630 K, (35 ± 10) R⊙, and (9100± 540) L⊙. For V725 Tau, these parameters are 6200 ± 940 K, (27 ± 6) R⊙, and (980 ± 420) L⊙. The 1.25–5 μm radiation from X Per at different epochs can be represented as a sum of contributions from at least three sources: the optical component and two objects emitting as BBs. To reproduce the 1.25–3.5 μm radiation from V725 Tau, two components are sufficient: the optical component and a single variable BB object. For both binary systems, orbital variations of the IR brightness can be noted near the Be-star phase. The amplitudes of the J-band variations of X Per and V725 Tau are about 0.3 m and 0.1 m , respectively.  相似文献   

2.
Absorption of the synchrotron emission of the quasar 3C 345 in the continuum and H(93–95)α and H(78–79)α radio recombination lines is studied. The upper limit for absorption in the H(93–95)α lines is Tal/Tac < 0.7%; absorption in the H(78–79)α lines with antenna temperature Tal = 25 mK, linewidth Δf = 5.3 ± 0.08 MHz, and Tal/Tac ≥ 0.3% has been detected. A correction to the redshift Δz = 0.00135 ± 0.00008 (z = 0.59365) has been determined.  相似文献   

3.
The results of spectroscopic observations of the host galaxies of objects in the RC catalog (the “Big Trio” program) obtained using the new SCORPIO spectrograph of the Special Astrophysical Observatory are presented. The spectroscopic redshifts of the objects are compared with their photometric color redshifts, and the errors in the latter are estimated. Based on BV RI observations obtained on the 6-m telescope of the SAO, the errors for the population of powerful radio galaxies are close to those found previously for radio quiet galaxies (about 10–20%). The detection of Ly α in the B filter in RC 1626+0448 is confirmed. This object is the second spectrally studied FR II radio source from the RC catalog to have a redshift z>2.5. Star formation in its host galaxy began at a redshift z>3.3. This first use of the new SCORPIO spectrograph demonstrates its promise for studies of very distant steep-spectrum radio galaxies brighter than 23m–24m in V.  相似文献   

4.
Particles can be accelerated to ultrahigh energies E≈1021 eV in moderate Seyfert nuclei. This acceleration occurs in shock fronts in relativistic jets. The maximum energy and chemical composition of the accelerated particles depend on the magnetic field in the jet, which is not well known; fields in the range ～5–1000 G are considered in the model. The highest energies of E≈1021 eV are acquired by Fe nuclei when the field in the jet is B≈16 G. When B～(5–40) G, nuclei with Z<10 are accelerated to E≤1020 eV, while nuclei with Z≥10 acquire energies E≥2×1020 eV. Only particles with Z≥23 acquire energies E≤1020 eV when B～1000 G. Protons are accelerated to E<4×1019 eV, and do not fall into the range of energies of interest for any magnetic field B. The particles lose a negligible amount of their energy in interactions with infrared photons in the accretion disk; losses in the thick gas-dust torus are also negligible if the luminosity of the galaxy is L≤1046 erg/s and the angle between the normal to the galactic plane and the line of sight is sufficiently small, i.e., if the axial ratio of the galactic disk is comparatively high. The particles do not lose energy to curvature radiation if their deviations from the jet axis do not exceed 0.03–0.04 pc at distances from the center of R≈40–50 pc. Synchrotron losses are small, since the magnetic field frozen in the galactic wind at R≤40–50 pc is directed (as in the jet) primarily in the direction of motion. If the model considered is valid, the detected cosmic-ray protons could be either fragments of Seyfert nuclei or be accelerated in other sources. The jet magnetic fields can be estimated both from direct astronomical observations and from the energy spectrum and chemical composition of cosmic rays.  相似文献   

5.
We have carried out a detailed identification of lines in the optical spectrum of the post-AGB star V510 Pup associated with the infrared source IRAS 08005-2356 based on observations with high spectral resolution. Absorption lines of the ions FeII, TiII, CrII, and YII are present at wavelengths from 4549 to 8546 Å. The absorption by YII and other s-process elements is anomalously strong, and the absorption is also strong in the circumstellar C2 Swan bands. The profiles of most of the lines (of hydrogen and metals) display P Cygni absorption-emission profiles. All the absorption lines are shifted toward the blue, suggesting an outflow of stellar material. The expansion velocity of the envelope derived from the Swan bands arising there is V exp =42 km/s. The highest wind velocity determined from the absorption wings of the FeII(42) P Cygni profiles reaches 240 km/s. Based on the star’s kinematic characteristics and the amount of interstellar absorption, it is at a distance of d≈3?4 kpc, which corresponds to an absolute magnitude of Mv≈?6m.  相似文献   

6.
Nutrient sources of San Quintin Bay, a coastal lagoon affected by coastal upwelling off Baja California (Mexico), were traced using generalized additive (mixed) models (GAMM) to the stable nitrogen isotopic composition, C:N and N content of two co-occurring macrophytes (the macroalgae Ulva spp. and the seagrass Zostera marina). The geochemical tracers followed a spatial trend that partly responded to the long-term nutrient gradient from the ocean towards the interior of the bay. N content in Z. marina and Ulva spp. decreased linearly (while C:N increased) towards the middle section of the bay to concentration levels that indicate potential N limitation for growth. Concurrently midway into the bay (6–9 km), the δ15N of both macrophytes showed a gradual enrichment in 15N reflecting progressive denitrification. The spatial pattern of δ15N and the decrease in C:N of the macrophytes towards the innermost section of the bay indicated an additional nonoceanic source of dissolved nitrogen in this zone. The similarity of the δ15N pattern of Z. marina and Ulva spp. implies that their δ15N composition is mainly controlled by the availability of N, in spite of the physiological differences between taxa. A better fit of GAMM to N content and C:N was obtained for Z. marina than for Ulva spp. indicating that the former delineate more steadily and smoothly the influence of upwelling along the spatial gradient. Nonetheless, Ulva spp. may be analyzed in combination with Z. marina to characterize the environmental conditions at the time of sampling.  相似文献   

7.
We present a new normalization for the linear density-perturbation spectrum in a multi-parameter model of the Universe. Using the differential mass function for the nearly galaxy clusters obtained from optical data, we have constructed a functional relation between the dispersion of the density contrast σ 8 on the scale 8h ?1 Mpc and the cosmological parameters Ω m , ΩΛ, h, n, f v for each of three theoretical approximations of the mass function: Press-Schechter, Sheth-Tormen and Jenkins. An extended class of models of the Universe with general spatial curvature include four parameters for the matter components: baryons (Ω b ), “cold” dark matter (Ω c ), “hot” dark matter (Ω v ), and the vacuum energy (ΩΛ). It is shown that the most accurate normalization of the power spectrum is achieved with the Sheth-Tormen approximation.  相似文献   

8.
We analyze four high resolution rich samples of Ly-α and metal lines (two at z ≥ 2 and two at z ≤ 0.2). We describe evolution of the observed Doppler parameters and absorbers separation and propose a model of the forest. We argue that all absorption lines are formed in gaseous caustics created in stable DM subclouds. The absorption lines are described by two local characteristics, the Doppler parameter and the column density of neutral hydrogen. We show that evolution of the Doppler parameter is very slow and its mean value increases by a factor ≤1.5 at redshifts 0 ≤ z ≤ 3. We show that absorbers separation increases as <dsep ∝ (1 + z)?2. We describe evolution of absorbers in the framework of a two component model: the first population represents absorbers with just one line created in compact stable DM clouds with random spatial distribution, and the second population includes absorbers with two, three and more absorption lines formed in more massive and extended random DM clouds. Slow evolution of the Doppler parameter indicates high stability of caustics and conditions within clouds. For absorbers of the second population relative velocity of lines slowly increases with time.  相似文献   

9.
In this study, single crystals of pure enstatite (Mg2Si2O6) were synthesised under water-saturated conditions at 4 and 8 GPa and 1,150°C with variable silica activity, leading to phase assemblages enstatite + forsterite, enstatite or enstatite + coesite. Run products were investigated using an FTIR spectrometer equipped with a focal plane array detector enabling IR imaging with a lateral pixel resolution of 2.7 μm. IR spectra within the OH-absorption region show two different groups of absorption bands: group 1 (wavenumbers at 3,592 and 3,687 cm?1) shows strongest absorptions for E||n β, whereas group 2 (wavenumbers at 3,067 and 3,362 cm?1) shows strongest absorptions for E||n γ. The groups are related to different defect types, group 1 to tetrahedral defects (T-site vacancies) and group 2 to octahedral defects (M-site vacancies). The intensity ratio of the bands within one group (i.e. A 3067/A 3362 and A 3592/A 3687) and the intensity ratio of E||n γ and E||n α in group 2 bands remain constant within error. In contrast, the intensity ratio of group 2 to group 1 absorption bands [e.g. (A 3362)/(A 3687)] is sensitive to the SiO2 activity and pressure. On the basis of the results of this and previous studies, a barometer for pure orthoenstatite coexisting with forsterite can be formulated:\( P\,[{\text{GPa}}] = 1.056 + \sqrt {{\frac{{1.025 - A_{{\left( {3362} \right)/\left[ {(3362) + (3687)} \right]}} }}{0.009}}} , \) where A (3362) and A (3687) are the integral absorbances of the component E||n γ of the absorption bands at 3,362 cm?1 and the component E||n β of the absorption band at 3,687 cm?1, respectively.  相似文献   

10.
The space distribution of quasars from the 2dF and SDSS DR5 catalogs in the redshift interval 0.3 < z < 1.9 is analyzed. The distributions of quasars in both catalogs are found to have the following common features: (1) when the distance between the nearest objects exceeds 35h ?1 Mpc (where h = H 0/100 km/s Mpc is the dimensionless Hubble constant), the distribution of quasars virtually coincides with a uniform three-dimensional distribution; (2) on scale lengths of (5–35)h ?1 Mpc, the fractal dimension of the quasar distribution is 2.3; (3) the amplitude of quasar clustering and the average distance between neighboring quasars increase slowly with z (at a significance level of about 1.5σ). Twenty large groups of quasars with sizes of (50–150)h ?1 Mpc can be identified in the 2dF catalog at the 4σ significance level. These groups are incipient superclusters (two earlier known groups are confirmed). The space density of these groups is of the order of 7h 3 Gpc?3.  相似文献   

11.
Because of economic and technical limitations, measuring solar energy received at ground level (R s ) isn’t possible in all parts of the country, and in only 12% of synoptic stations is this parameter measured and recorded. Thus, it should be estimated and modeled spatially based on other climatic variables using mathematical methods. In this research, many attempts have been made to introduce an air temperature-based model for Rs estimation, and then, based on the output of the mentioned models, several geostatistical methods have been tested, and finally an elegant spatial model is proposed for (Rs) zoning in Iran. In this regard, the relationships between the measured amounts of monthly solar radiation and other climatic parameters, such as a monthly average, maximum and minimum temperature, precipitation, relative humidity, and the number of sunny hours during the period 1970–2010, are examined and modeled. It was revealed that based on the linear relationship between the monthly average air temperatures and solar radiation values recorded in each of the stations, that the best-fit linear model, with R 2  = 0.822, MAE = 1.81, RMSE = 2.51%, and MAPE = 10.08, can be introduced for Rs estimation. Then, using the outputs of the proposed model, the amounts of (R s ) are estimated in another 171 meteorological stations (a total of 192 stations), and eight geostatistical methods (IDW, GPI, RBF, LPI, OK, SK, UK, and EBK) were investigated for zoning. Comparing the resulting variograms showed that in addition to proof of spatial correlation between solar radiation data, they can be applied for modeling changes in various directions. Analyzing the ratio of the nugget effect on the roof of the variograms showed that the Gaussian model with the lowest ratio (Co/Co + C = 0.883) and (R 2  = 0.972), could model the highest correlation between the data and, therefore, it was used for data interpolation. To select the best geostatistical model, R2, MAE, and RMSE were used. On this basis, it was found that the RBF method with R 2  = 0.904, MAE = 3.02, RMSE = 0.39% is the most effective. Also, the IDW method with R 2  = 0.90, MAE = 3.08, RMSE = 0.391%, compared to other methods is the most effective. In addition, for data validation, correlations between observed and estimated values of solar radiation were studied and found R 2  = 0.86.  相似文献   

12.
The excitation of methanol in the absence of external radiation is analyzed, and LTE methods for probing interstellar gas considered. It is shown that rotation diagrams correctly estimate the gas kinetic temperature only if they are constructed using lines whose upper levels are located in the same K-ladders, such as the J0?J?1E lines at 157 GHz, the J1?J0E lines at 165 GHz, and the J2?J1E lines at 25 GHz. The gas density must be no less than 107 cm?3. Rotation diagrams constructed from lines with different K values for their upper levels (e.g., 2K?1K at 96 GHz, 3K?2K at 145 GHz, 5K?4K at 241 GHz) significantly underestimate the temperature, but enable estimation of the density. In addition, diagrams based on the 2K?1K lines can be used to estimate the methanol column density within a factor of about two to five. It is suggested that rotation diagrams should be used in the following manner. First, two rotation diagrams should be constructed, one from the lines at 96, 145, or 241 GHz, and another from the lines at 157, 165, or 25 GHz. The former diagram is used to estimate the gas density. If the density is about 107 cm?3 or higher, the latter diagram reproduces the temperature fairly well. If the density is around 106 cm?3, the temperature obtained from the latter diagram should be multiplied by a factor of 1.5–2. If the density is about 105 cm?3 or lower, then the latter diagram yields a temperature that is lower than the kinetic temperature by a factor of three or more, and should be used only as a lower limit for the kinetic temperature. The errors in the methanol column density determined from the integrated intensity of a single line can be more than an order of magnitude, even when the gas temperature is well known. However, if the J0?(J ? 1)0E lines, as well as the J1?(J ? 1)1A+ or A? lines are used, the relative error in the column density is no more than a factor of a few.  相似文献   

13.
We use a sample of 808 quasars selected by Risaliti and Lusso to estimate two important cosmological parameters: the percentage of matter in the Universe Ωm and the Hubble constant. The method is based on an auxiliary experimental correlation between the luminosity of quasars in the Xray band and UV band in the form log LX = β + γ log LUV. For the flat ΛCDM model our fit gives Ω m = 0.21 ± 0.12. Our main results are the following: firstly, the fraction of matter (baryonic + dark) contained in the Universe is 21% according to our estimate and is smaller than the one found by other authors using Type Ia Supernovae (though, considering the large error, our result is consistent with the supernova data). Secondly, the Einstein–de Sitter model is outside the 95% confidence interval of our best fit curve. In order to determine also the Hubble constant, we were compelled to fix one of the free parameters (β, γ,H0,Ω m ) and to determine the others with the non-linear least square method. We have proceeded in two different ways. Increasing h0 = H0/100 with a step of 0.01 in the range from 0.65 to 0.95, we obtain a Hubble constant H0 = 74.6± 2.4 (km/s)/Mpc in agreement with the values found using CMB, supernovae and cepheids. On the other hand, increasing the parameter m = β/γ with a step of 0.03 in the range from 13.4 to 14.4, we obtain the same result (but with a greater statistical error), and hence a self-consistentmodel, only assuming β ≥ 8.21.  相似文献   

14.
It is shown that a model with accretion in a “quasi-propeller” mode can explain the observed spindown of pulsars with periods P<0.1 s. The mean accretion rate for 39 selected objects is \(\dot M = 5.6 \times 10^{ - 11} M_ \odot /year\). If \(\dot M\) is constant during the pulsar’s lifetime, the neutron star will stop rotating after 107 years. The mean magnetic field at the neutron-star surface calculated in this model, \(\bar H_0 = 6.8 \times 10^8 G\), is consistent to an order of magnitude with the values of H0 for millisecond pulsars from known catalogs. However, the actual value of H0 for particular objects can differ from the catalog values by appreciable factors, and these quantities must be recalculated using more adequate models. The accretion disk around the neutron star should not impede the escape of the pulsar’s radiation, since this radiation is generated near the light cylinder in pulsars with P<0.1 s. Pulsars such as PSR 0531+21 and PSR 0833-45 have probably spun down due to the effect of magnetic-dipole radiation. If the difference in the braking indices for these objects from n=3 is due to the effect of accretion, the accretion rate must be of the order of 1018 g/s.  相似文献   

15.
We present the results of our IR photometric observations of the classical symbiotic star BF Cyg acquired in 1978–2003. The variability range in the J and K bands was ～0.2m. A periodic component in the cool star’s brightness variations is clearly visible, its period being half the orbital one and its J amplitude being ～0.15m. This component is associated with the ellipsoidal shape of the red giant, which model calculations show fills its Roche lobe. This is required in order to reproduce ellipsoidal brightness variability with such a large amplitude: the calculated amplitude for a red giant filling 90% of its Roche lobe is half the observed value. At the same time, it was not possible to confidently chose the optimum component-mass ratio, q = M giant /Mhot, and orbital inclination, i, from possible values in the ranges q = 2–4, i = 70°–90°. Including the contribution from the hot radiation sources (the hot component and ionized envelope), which vary with a period equal to the orbital period, has a considerable influence on the estimated parameters associated with the red giant’s ellipsoidal brightness variations, and this contribution cannot be neglected. The deviations of the observed from the calculated light curve are irregular, with the rms deviation being σ(O-C) ≈ 0.04m.  相似文献   

16.
We present the results of our CCD photometric and moderate-dispersion spectroscopic observations of the binary system V4641 Sgr, which contains a black hole of mass ≈9.5M⊙ and a normal B9III star. The photometric light curve reveals an ellipticity effect with very high amplitudes in V and R, 0.40m and 0.37m, and the color curve shows that the surface temperature is nonuniform. All this testifies to tidal distortion of the normal star's surface due to the massive companion and to a high inclination of the orbit to the line of sight. In June and July 2002, during quiescence, we obtained data during three flares with amplitudes up to 0.26m. In particular, spectroscopic observations were acquired near the time of the black hole's inferior conjunction. One hour before conjunction, a depression by EW=0.5 Å was observed in the red wing of the Hα absorption line, interpreted as absorption by gas flowing in the direction from the observer toward the normal star. This flow is apparently associated with a rarefied gas disk around the black hole, and the conjunction grazes the stellar surface if the orbital inclination is close to 70.7°. The maximum velocity along a circular Keplerian orbit is 650 km/s at a distance of R=0.15–0.20a from the black hole (where a is the component separation). Thus, we find the mass of the black hole to be M BH =7.1–9.5M⊙, confirming the model of Orosz et al. (2001).  相似文献   

17.
We obtained speckle interferometric and spectroscopic observations of the system 41 Dra during its periastron passage in 2001. The components’ lines are resolved in the spectral interval 3700–9200 Å. The observed wavelength dependence of the brightness difference between the components is used to estimate the B-V indices separately for each of the components: B-V = 0.511 for component a and B-V = 0.502 for component b. We derived improved effective temperatures of the components from their B-V values and hydrogen-line profiles. The observations can be described with the parameters for the components T eff a = 6370 K, log ga = 4.05 and T eff b = 6410 K, log gb = 4.20. The iron, carbon, nitrogen, and oxygen abundances in the atmospheres of the components are log N(Fe)a = 7.55, log N(Fe)b = 7.60, log N(C)a = 8.52, log N(C)b = 8.58, log N(N)a = 8.05, log N(N)b = 7.99, log N(O)a = 8.73, log N(O)b = 8.76.  相似文献   

18.
Measurements of the broadening of pulsar pulses by scattering in the interstellar medium are presented for a complete sample of 100 pulsars with Galactic longitudes from 6° to 311° and distances to three kiloparsec. The dependences of the scattering on the dispersion measure (τ sc(DM) ∝ DMα), frequency (τ sc(v) ∝ v ?γ ), Galactic longitude, and distance to the pulsar are analyzed. The dependence of the scattering on the dispersion measure in the near-solar neighbourhood can be represented by the power law τ sc(DM) ∝ DM2.2±0.1). Measurements at the low frequencies 111, 60, and 40 MHz and literature data are used to derive the frequency dependence of the scattering (τ sc(v) ∝ V ?γ ) over a wide frequency interval (covering a range of less than 10: 1) with no fewer than five frequencies. The index for the frequency dependence, γ = 4.1 ± 0.3, corresponds to a normal distribution for inhomogeneities in the turbulence in the scattering medium. Based on an analysis of the dependence of the scattering on the distance to the pulsar and on Galactic longitude, on average, the turbulence level C n 2 is the same in all directions and at all distances out to about three kpc, testifying to the statistical homogeneity of the turbulence of the scattering medium in the near-solar region of the Galaxy.  相似文献   

19.
Both abiotic and biotic factors govern distributions of estuarine vegetation, and experiments can reveal effects of these drivers under current and future conditions. In upper San Francisco Estuary (SFE), increased salinity could result from sea level rise, levee failure, or water management. We used mesocosms to test salinity effects on, as well as competition between, the native Stuckenia pectinata (sago pondweed) and invasive Egeria densa (Brazilian waterweed), species with overlapping distributions at the freshwater transition in SFE. Grown alone at a salinity of 5, E. densa decreased fivefold in biomass relative to the freshwater treatment and decomposed within 3 weeks at higher salinities. In contrast, S. pectinata biomass accumulated greatly (~4× initial) at salinities of 0 and 5, doubled at 10, and was unchanged at 15. When grown together in freshwater, S. pectinata produced 75 % less biomass than in monoculture and significantly more nodal roots (suggesting increased nutrient foraging). At a salinity of 5, a decline in E. densa performance coincided with a doubling of S. pectinata shoot density. Additional experiments on E. densa showed elevated temperature (26 and 30 °C) suppressed growth especially at higher salinities (≥5). We conclude that salinity strongly influences distributions of both species and that competition from E. densa may impose limits on S. pectinata abundance in the fresher reaches of SFE. With a salinity increase of 5, S. pectinata is likely to maintain its current distribution while spreading up-estuary at the expense of E. densa, especially if increased temperature also reduces E. densa biomass.  相似文献   

20.
A technique for IR spectroscopic determination of the total nitrogen content N S in the form of A-and B 1-defects is suggested. It provides for the computer processing and decomposition of IR spectra into constituent bands, calculation of the total absorption band area S N and individual areas S A and S B1 and their normalization with respect to the total area of the diamond intrinsic absorption S 0, with the normalization coefficients K S , K A , and K B1 being calculated. Based on the analysis of the IR spectra of 60 octahedral diamond crystals from the Mir and Yubileinaya pipes (Sakha-Yakutiya), the empirical functions N S = 911.85 K S 0.9919 ppm (R 2 = 0.9859), N A = 1185.6 K A 1.1511 ppm (R 2 = 0.8703), and N B1 = 911.85 K S 0.9919 ? 1185.6 K A 1.1511 ppm have been defined.  相似文献   

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