Infrared excess in Wolf-Rayet stars

On the basis of continuum energy distributions in the wavelength region 3200–11 000 Å, effective temperature for 14 Wolf-Rayet stars are estimated by comparing with Kurucz (1979) model atmospheres. The continuum energy distribution curve shows strong infrared excess emissions above of 5000 Å in every star.     

The wavelength dependence of granulation (0.38–2.4 μm)

Using 2 pinhole photometers the intensity of the undisturbed photosphere was recorded simultaneously in 6 and in 4 wavelength regions. The rms value of the intensity variation in each of the 10 wavelength regions decreases slightly with increasing value of the heliocentric angle; this result confirms recent observations by other authors and supports the critique of the results given by Edmonds (1964).We report the detection of a secondary maximum in the wavelength dependence of the intensity variation at 1.5 m.     

Сопоставление модели карлсона с моделью сплошной среды

, (1962, 1963) . , (1) (2) .     

Scanner observations of the Be starsν Gem,κ Ori,β Mon andω CMa

The photoelectric spectrophotometric scans of the Be stars Gem, Ori, Mon and CMa have been analyzed to find out few stellar parameters. The absolute energy distributions of these stars in the wavelength range 350–750 nm have been given. Their effective temperatures and gravities have been estimated from comparisons with non-LTE model atmospheres. The stars Gem and Mon have been found to have Balmer discontinuities in emission. The excess emission in the region 620–750 nm has been observed for Mon and CMa. The evolutionary aspects of these stars are discussed and their masses have been estimated.     

ОJ 287: Поляризационное и фотометрическое поведение В 1971–1976 гг

J 287 1972–1976. , . . J ( ), () . (₀=80°) . J 287 ¶ . p=42.8%, ₀=101°. (50%).     

F07164+5301: an ESB source with WR features

We report on a new ESB source, as defined by Allenet al. (1991), with Wolf-Rayet (WR) bands in its optical spectrum. The WR bump at 4605-4686 is detected. The bump consists of broad HeII 4686, NV4605-4619, NIII4634-41, and possibly, CIII4647-52 emission. The narrow nebular lines are clearly discernable on our spectrum. The number of WR stars derived from the luminosity of HeII4686 is about 8100. The oxygen abundance is about 9.06×10^–4, greater than the solar value.     

Возможный механизм радиоизлучения пульсаров

, , , , , . , , . - . — , , .     

Distribution of polarization and intensity of radiation across the stellar disk and numberical values of atmospheric characteristics governing this distribution

Computations of polarization and intensity of radiation from a unit stellar surface area are presented, as well as a study of the numerical characteristics of atmospheres — single-scattering albedo and the initial source function(), which define the polarization behaviour of atmospheres. The radiatively stable models of stellar atmospheres presented by Kuruczet al. (1974) and Kurucz (1979) have been used for calculations. Since the versus optical depth dependence is rather weak, it has been assumed that (=cost. With a fixed effective temperatureT _eff maximum values of are characteristic of stars featuring the lowest surface gravity accelerationg. Among stars with radiatively stable atmospheres, maximum values of (=5000 Å) 0.4–0.6 are exhibited by supergiants withT _eff=8000–20 000 K. The plot of () is characterized by discontinuities at the boundaries of spectral series for hydrogen and, sometimes, for helium. Maximum are attained in the Lyman region of =912–1200 Å, where can reach the value 0.7–0.9 for supergiants, this value being 0.3 for Main-Sequence stars. For stars withT _eff 35 000 K, high values of also are attained for <912 Å. Within the infrared region, is always small because of bremsstrahlung absorption.A rapid growth of the source functionB with < typical for ultraviolet range (within the Wien part of spectrum), together with high values of results in the strong polarization of emission from a unit stellar surface element, sometimes exceeding the values for the case of a pure electron scattering. For longer wavelengths, where the limb-darkening coefficient is smaller, the plane of polarization abruptly turns 90° in the central parts of the visible stellar disk.     

Об устойчивости лагранжевых решений пространственной эллиптической задачи трех тел

. . ,e, , . . e, . , .

---

Stability of the librational triangular points of the three-dimensional elliptic restricted three-body problem is studied. The problem is solved in the non-linear statement at the small values of eccentricity.For all values ofe, , besides ones which correspond to the resonances of the third and the fourth order the librational points are stable taking into account the terms up to the fourth order in the normal form of the Hamiltonian function of the perturbed motion.At sufficiently smalle and the non-stability in sense of Liapunov has been proved. The approximate equations of the boundary of the stability area in the planee, has been obtained. The cause of the non-stability is an equality of the rotational period of the principal attracting masses in the elliptic orbit and the period of oscillation of indefinitely small mass along the direction perpendicular to the plane of their motion.

     

Pitch angle scattering of solar particles: Comparison of ‘particle’ and ‘field’ approach

In the quasi-linear theory of pitch angle scattering the power spectrum of magnetic field fluctuations is related to the shape of the pitch angle diffusion coefficient D(), the absolute value of the mean free path , and the rigidity dependence of the mean free path (R). We discuss these relations in detail during the solar particle event of 11 April, 1978 which was observed on HELIOS-2 at a distance of 0.49 AU from the Sun. Magnetic field measurements obtained during the time of the event are used as a basis for the layer model in which the method of particle trajectories in an actually measured field is used to simulate pitch angle diffusion. The values of D() and based on the trajectory simulation for 100 MeV protons (field approach) are compared with results obtained from solar proton data (particle approach) and with predictions from quasi-linear theory based on the additional assumption of the slab model for magnetic field fluctuations (QLT approach). The time of the event is characterized by a high level of field fluctuations, the observed mean free path of about 0.03 AU for 100 MeV protons is smaller than the average value near 1 AU. Results from the field and particle approaches agree surprisingly well. The remaining difference in the mean free path of about a factor of 2 could be due to tangential discontinuities which are measured by the magnetometer, but not seen by the real particles traveling along the average field. The results from the field and QLT approaches based on the same set of magnetic field measurements differ by about a factor of 4. One of the reasons for this discrepancy is that the conditions for resonance scattering are only marginally valid. In addition, the wave vectors representing Alfvén-type fluctuations may not be totally field aligned. This deviation from the slab model would cause an increase of the theoretically predicted mean free path and lead to better agreement with the other two approaches.     

Scanner observations of comet P/Crommelin 18181

Spectral scans of the coma of comet P/Crommelin 1818. I have been obtained in the wavelength range 3200–6500 Å. Strong emission features of CN(3883 Å) and C₂ Swan bands (4695, 5165, and 5538 Å) have been identified. Some weak emission features of CH(3890 Å), C₃(4050 Å), CN(4200 »), and C₂ + CH(4358 ») were also detected. Sodium was found to be absent in this comet. An estimate of CN and C₂ abundances has been made and their production rate have been derived.     

Взаимооействие Излучения Рентгеновскооо Истооника с АтмосФерой Нормальной Звезды в Тесных Двойных Системах

, . : , . , . . ( ) . . . HZ Her=Her X1, . . , . , ., hv 15–30 . , . Sco X1 .     

Индуцированное комптоновское рассеяние изотропного излучения релятивистскими электронами

, kT _b mc ² . . , , . E ^–5, - E ², mc ²(kT /mc ²)^1/7. , (>2.10⁵ cm ^–3) . , -, , .     

Spectrophotometry of Comet Bradfield (1980t) during post-perihelion period

Spectrum scans of the head of Comet Bradfield (1980t) covering the wavelength range 365–640 nm were made on two nights when the heliocentric distance of the comet varied from 0.55 to 0.58 AU. The emission features of the CN band at 388 nm and Swan band sequence of C₂ at 474 nm, 516 nm, and 563 nm are identified and absolute fluxes in these bands as well as in the continuum are derived. The continuum energy distribution curves of the comet have been compared with those of the Sun and the star Crv (G5 III). An estimate of the number of C₂ and CN molecules in the head of the comet has been made through the measured intensities of their respective bands lying in this region.     

The neutral interface adjoining theHII region DR21

Observations of C100 and C125 atomic carbon recombination lines were made at the Algonquin Radio Observatory, towards the neutral interface separating theHii region DR21 (at RA=20^h37^m14^s, Dec=+42°0900) from its associated molecular cloud. An analysis of the Cn observations in conjunction with a simple model of a neutral interface enabled the derivation of the following parameters: electron density of 300 cm^–3, electron temperature of 30 K, microturbulent velocity of 2.3 km s^–1, and depth of the neutral interface of 0.01 pc. A single,stimulated emission model is sufficient to reproduce the Cn observations in the wavelength range from 4.6 cm (C100) to 21 cm (C166). All the known Cn data do support a pressure equilibrium between the neutral interface and theHii region, after the usual allowance is made for carbon depletion on grains.     

The solar continuum from 900 to 130 000 Å and the photospheric temperature model

In order to obtain a better agreement between observed and computed values of the solar intensity, an improved temperature distribution is deduced for the range 0.02<0< 10. The intensity observations here considered refer to the wavelength region between 1980 and 129 500, and the center-limb variations generally go down to cos = 0.1. The improved model, given in Figure 4 and Table II, differs rather little from the Utrecht 1964 model, used here as a reference.It appears necessary to introduce an empirical correction function to be applied to the continuous absorption coefficient. This function was derived for the spectral region between 2000 and 130000 Å; it is shown in Figure 5.Furthermore, an extension of the model (1.10^–7<0< 2.10^–2) is deduced (see Table III and Figure 8), which reasonably well represents the observations of the ultraviolet solar flux ( 900–1700 Å).     

A new microwave/X-ray diagnostic for the thermal phase of solar flares

We have observed 10 solar bursts during the thermal phase using the Haystack radio telescope at 22 GHz. We show that these high frequency flux observations, when compared with soft X-ray band fluxes, give useful information about the temperature profile in the flare loops. The microwave and X-ray band fluxes provide determinations of the maximum loop temperature, the total emission measure, and the index of the differential emission measure (q(T)/T = cT^–1). The special case of an isothermal loop ( = ) has been considered previously by Thomas et al. (1985), and we confirm their diagnostic calculations for the GOES X-ray bands, but find that the flare loops we observed departed significantly from the isothermal regime. Our results ( = 1–3.5) imply that, during the late phases of flares, condensation cooling ( 3.5) competes with radiative cooling ( 1.5). Further, our results appear to be in good agreement with previous deductions from XUV rocket spectra ( 2–3).     

Velocity waves in the quiet solar chromosphere

Propagation of velocity waves are investigated in the solar chromosphere, with a special view to high frequencies (periods 60 s). Four line profiles have been observed during 27 mn with the Sacramento Peak vacuum telescope (H, 3933, 8498 and 8542 Ca ii). Three Fourier analysis are performed according to the location in the cells of the chromospheric network. Phase-shifts and amplitude ratios between the line Doppler shifts are computed as functions of frequency. The pollution of high frequency results by energetic low frequency oscillations is investigated.H Doppler shifts are probably affected by the large width of line formation layers (low transfer function). Using formation altitudes for Doppler shifts previously computed for the infra-red lines, we show that acoustic waves propagating upwards cannot account for the observations. In particular, the phase-shifts between oscillations in different chromospheric layers are much smaller than theoretical predictions. As a first attempt for a qualitative agreement, we suggest that most of the high frequency oscillations (10–15 mHz) are magnetoacoustic waves, travelling in layers where the gradient of the Alfvén-speed cannot be neglected, and reflected at the top of the chromosphere. The amplitudes of these waves are probably underestimated as derived from the observed Doppler shifts.     

The extinction coefficients in mid- and farinfrared of silicate and iron-oxide minerals of interest for astronomical observations

Extinction measurements were made for some silicate and iron-oxide mineral grains in mid- and far-infrared region. For far-infrared region, high temperature magnesium silicates such as olivine and pyroxenes show the absorption spectra of steep dependence as ^–3 ( being the wavelength) with some peak structure, but the spectrum of magnetite shows ^–1 dependence.     

A high resolution mid-infrared image of the Starburst Galaxy M82

We have produced high-resolution images of the nuclear region of M82 with SpectroCam-10, a mid-infrared instrument at the Palomar 5 m telescope. These images were taken at 11.7 m and 9.8 m with a 1m filter bandpass at the diffraction limit of 0.6 arcsec, making them the highest resolution maps yet available of M82. In addition, we have obtained high-resolution (/=2000) maps of the velocity field of the nuclear disk of M82 in the 12.81 m line emission of [NeII]. In these proceedings we present the 11.7 m image, which will appear together with the 9.8 m map and the [Ne II] spectra in a subsequent paper, now in preparation. This image shows very clearly a bridge structure joining the eastern and western clusters.