Photometry of BD −7° 3007

Photometric observations of BD –7° 3007 in B and V filters are reported. Rapid flickering appears to be present at all phases, implying an unfavourable angle of inclination of orbit for seeing eclipse effects. A modulation of the light curve of period about an hour is present only on one night. The continuum energy distribution agrees with that of Com (GO V) in the longer wavelength region only.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.     

Model Estimates of Non-Hydrostatic Stresses in the Martian Crust and Mantle: 2−Three-Level Model

Regions of maximum shear and tension-compression stresses in the Martian interior have been revealed using the three-level compensation model. Nonequilibrium relief, density anomalies at the crust?mantle boundary, and density anomalies at the base of the lithosphere are the sources of the anomalous gravitational field. The thickness of elastic lithosphere positioned on a weak layer that has partially lost its elastic properties varies from 150 to 500 km. The weakening of the layer under the lithosphere is simulated by a tenfold lower value of the shear modulus down to the core boundary. In general, the stresses for the threelevel compensation model differ from the values obtained for the two-level model (nonequilibrium relief and density anomalies at the crust?mantle boundary are the sources of the anomalous gravitational field) by 5?10%. Considerable differences between the models of two-level and three-level compensation are revealed beneath Hellas and Argyre regions.     

Scientific detector workshop 2022 on-sky performance verification of near-infrared e−APD technology for wavefront sensing and demonstration of e−APD pixel performance to improve the sensitivity of large science focal planes

Near-infrared adaptive optics as well as fringe tracking for coherent beam combination in optical interferometry require the development of high-speed sensors. Because of the high speed, a large analog bandwidth is required. The short exposure times result in small signal levels which require noiseless detection. Both requirements cannot be met by state-of-the-art conventional CMOS technology of near-infrared arrays as has been attempted previously. A total of five near-infrared SAPHIRA 320 × 256 pixel HgCdTe e⁻APD arrays have been deployed in the wavefront sensors and in the fringe tracker of the VLTI instrument GRAVITY. The current limiting magnitude for coherent exposures with GRAVITY is m_k = 19, which is made possible with ADP technology. New avalanche photo-diode array (APD) developments since GRAVITY include the extension of the spectral sensitivity to the wavelength range from 0.8 to 2.5 μm. After GRAVITY a larger format array with 512 × 512 pixels has been developed for both AO applications at the ELT and for long integration times. Since dark currents of <10⁻³ e⁻/s have been demonstrated with 1Kx1K e⁻APD arrays and 2Kx2K e⁻APD arrays have already been developed, the possibilities and adaptations of e⁻APD technology to provide noiseless large-format science-grade arrays for long integration times are also discussed.     

Rocket observation of E−B-field correlations showing up- and down-going poynting flux during an auroral breakup event

On 27 January 1979, the S23H rocket was launched from Esrange, Kiruna, Sweden, shortly after the onset of an intense auroral breakup over Northern Scandinavia. The high altitude and short range trajectory of the rocket carried the instruments twice through the same magnetic flux tubes demonstrating some time variation imposed on a spatial structure. Several regions of intense Birkeland current sheets were penetrated, and examples are given where the northward electric field showed anticorrelation, correlation, as well as no correlation with the westward magnetic field perturbations. This is interpreted as examples of down-flowing and up-flowing electromagnetic energy as well as regions of little exchange of energy between the magnetosphere and the ionosphere.     

CH3CN J = 8 − 7 and CS J = 3 − 2 emission in orion KL

The data of the line series CH₃CN 8(K) – 7(K) K = 0 – 7 and line CS J = 3 – 2 were taken simultaneously. At beam size of 16 the emissions of CH₃CN and CS have a common center position located near IRc2 with deviations -8 and 5. The observed data show that in Orion KL core the integrated intensities of the two species have double peaks separated by a space of 14. The 2-dimension Gaussian fitting plots (FWHM) are ellipses ofD _maj = 26 andD _min = 22 for CH₃CN 8(K) – 7(K) K = 3 – 6 andD_maj = 39 D_min = 31 for CS J = 3 – 2 at a distance about 450 pc. Towards the multiple line emission region of CH₃CN 8(K) – 7(K) K = 3 – 6, using a simplified very large velocity gradient model to solve the statistical equilibrium and radiative transfer equations, we find to fit the observed results, the optimum physical parameters and kinetic temperatureT _k 120 K, densityn(H _a) 1.2 × 10⁵ cm^–3, velocity gradientV _gr 92 km s^–1 pc^–1 and the local abundance of CH₃CNF _ab 3 × 10^–8. However towards the region of single line emission of CS J = 3 – 2 we have to use LTE and the optical thin approximation on the assumption ofT _k= 120 K to obtain the lower limits of column density and then, an averaged abundance of CS of 6 × 10^–8.     

Late-time emission of the type II Supernovae powered by the radioactive decay56Ni−56Co−56Fe

A one-zone model for the late time SN II energized by the radioactive decay⁵⁶Ni–⁵⁶Co–⁵⁶Fe is presented. The model succeeds in reproducing for the late time evolution of H and [Oi] 6300 emission lines in SN1970g for the reasonable set of parameters: mass of ejecta 4M , boundary velocityv ₀=4000 km s^–1 and amount of⁵⁶NiM _Ni=0.02M . However, a one-zone model does not account for the late time continuum. In the case of SN1980k the radioactive model fits H and [Oi] 6300 emissions att250 day satisfactory but fails at very late time, e.g.,t=670 day when the predicted value of the ratioL(H)/L(6300) is two orders of magnitude smaller than the observed one. We suggest that the strong H emission in SN1980k on the 670th day is due to the interaction of the supernova envelope with the pre-SN wind. The radioactive model for the late time SN II predicts strong Mgii 2800 line and detectable Hei 10830 line in emission and absorption.     

Synchrotron cooling and annihilation of ane +-e − plasma: The radiation mechanism for the 5 March, 1979 transient

Positron-electron pair radiation is examined as a mechanism that could be responsible for the impulsive phase emission of the 5 March, 1979 transient. Synchrotron cooling and subsequent annihilation of the pairs can account for the energy spectrum, the very high brightness, and the 0.4 MeV feature observed from this transient, whose source is likely to be a neutron star in the supernova remnant N49 in the Large Magellanic Cloud. In this model, the observed radiation is produced in the skin layer of a hot, radiation-dominated pair atmosphere, probably confined to the vicinity of the neutron star by a strong magnetic field. The width of this layer is only about 0.1 mm. In this layer, 10¹² generations of pairs are formed (by photon-photon collisions), cooled and annihilated during the 0.15 s duration of the impulsive phase. The very large burst energy implied by the distance of the LMC, and its very rapid release, are unsolved problems. We mention, nonetheless, the possibility of neutron star vibrations, which could transport the energy coherently to the surface, heat the atmosphere mechanically to a hot, pair-producing temperature, and have a characteristic damping time roughly equal to the duration of the impulsive phase.Paper presented at the Symposium on Cosmic Gamma-Ray Bursts held at Toulouse, France, 26–29 November, 1979.     

Large-scale mapping of the IRAS 0042 + 5530 region in the 12CO (J = 1−0) and 13CO (J = 1−0) molecular lines

We present new radio observations of molecular lines in the region of high mass star formation, namely G122.0-7.1. A large-scale map of the emission observed in the ¹²CO (J = 1−0) and ¹³CO (J = 1−0) lines covers the area of 15′ × 9′, revealing two dense regions. The molecular bipolar outflows have been resolved in ASO1 region. It is associated with the known candidate YSO nearby IRAS 0042 + 5530. Also, a new dense region has been discovered in the North-Western part of the G122.0-7.1 at a distance of 5′ from IRAS 0042 + 5530. Its position is close to the peak of 4850 MHz emission. The text was submitted by the authors in English.     

Energy spectra of cosmic ray nuclei: 4≤Z≤26 and 0.3≤E≤2 GeV amu−1

Energy spectra of cosmic ray nuclei in the charge range 5Z26 have been derived from the response of an acrylic plastic erenkov detector. Data were obtained using a balloon-borne detector and cover the energy range 320E2200 MeV amu^–1. Spectra are derived from a formal deconvolution using the method of Lezniak (1975). Relative spectra of different elements are compared by observing the charge ratios. Secondary-primary ratios are observed to decrease with increasing energy, consistent with the effect previously observed at higher energy. Primary-to-primary ratios are constant for 6Z10 and 14Z26 but vary for 10Z14. This data is found to be consistent with existing data, where comparable, and lends strong support to the idea of two separate source populations contributing to the cosmic ray composition.Work supported by University of Maryland Grant NGR 21-002-316.     

Astrometric Observations of the Galilean Moons of Jupiter at the Pulkovo Normal Astrograph in 2016−2017

We present the results of observations of the Galilean moons of Jupiter carried out at the Normal Astrograph of the Pulkovo Observatory in 2016?2017. We obtained 761 positions of the Galilean moons of Jupiter in the system of the Gaia DR1 catalog (ICRF, J2000.0) and 854 differential coordinates of the satellites relative to each other. The mean errors in the satellites’ normal places and the corresponding root-mean-square deviations are ε_α = 0.0020′′, ε_δ = 0.0027′′, σ_α = 0.0546′′, and σ_δ = 0.0757′′. The equatorial coordinates of the moons are compared to the motion theories of planets and satellites. On average, the (O–C) residuals in the both coordinates relative to the motion theories are less than 0.031′′. The best agreement with observations is achieved by a combination of the EPM2015 and V. Lainey-V.2.0|V1.1 motion theories, which yields the average (O–C) residuals of approximately 0.02″. Peculiarities in the behavior of the (O–C) residuals and error values in Ganymede have been noticed.     

Spectropolarimetry of the methane and ammonia bands of Jupiter between 6800 and 8200 Å

Spectropolarimetry of Jupiter at resolutions between 22 and 35 Å reveals a strong increase of linear polarization in the 7250-$\text{A}\text{?}$ CH₄ band. This is very probably due to the decreasing contribution toward the band center of the higher orders of scattering, which have a smaller net polarization than the first few orders. The linear polarization is also enhanced in the band at 7900 $\text{A}\text{?}$ comprising the 7920-$\text{A}\text{?}$ NH₃ and 7600- to 8200-$\text{A}\text{?}$ CH₄ bands. The normalized circular polarization shows a feature at 7250 $\text{A}\text{?}$ with a dispersion shape. This is most probably produced in a double-scattering process involving either a solid or liquid aerosol with an absorption at 7250 $\text{A}\text{?}$. Methane aerosols, the obvious candidates from a spectroscopic point of view, are, however, forbidden if current estimates of the Jovian atmospheric temperature are correct.     

First Byurakan Spectral Sky Survey. Stars of late spectral types. −11° ≤ δ ≤ −7° belt

A 10th list of late-type M and C stars found on plates of the First Byurakan Spectral Sky Survey in the − 11° ≤ δ ≤ − 7° belt with an area of about 1070 deg² is given. The list contains data on 169 red stars, 117 of which were found for the first time: 8 are new C stars, 3 are Cstar candidates, 104 are M stars, 1 is either an M or an S star, and 1 object on the survey plate cannot be classified. Of the 117 objects, 47 are unidentified IRAS sources. A statistical analysis of the objects that are and are not identified with IRAS sources shows that the identified stars are, with a high probability, brighter and have relatively more massive envelopes. Two stars were found to have fairly large brightness variability (with an amplitude of at least 6^m.O). Gasdust shells are assumed to exist around nine of the IRAS sources. The equatorial coordinates, spectral types, and stellar magnitudes, determined on Palomar E maps, are given for the selected objects. Translated from Astrofizika, Vol. 41. No. 4, pp. 545–559, October–December, 1998.     

Accumulation of Terrestrial and Outer Planets

Theoretical models of planetary accretion are tested against three major observational results from space exploration.These include (a) the late heavy bombardment event,(b) the mega-impact effects,and (c) the orbital configuration of the Kuiper belt objects.It is shown that these dynamical processes and orbital structures characteristic of the Solar System history can be fitted into a consistent scenario with the accretion of Uranus and Neptune acting as the driving mechanism.     

Chinese Journal of Astronomy and Astrophysics

An international bimonthly journal,founded in 2001 as a continuation of Acta Astrophysica Sinica (founded in 1981,ISSN 0253-2379).The Chinese Journal of Astronomy and Astrophysics (ISSN 1009-9271) is published for the Chinese Astronomical Society and the National Astronomical Observatories of Chinese Academy of Sciences by the Science     

Restitution coefficients and sticking velocities of a chondrule analogue colliding on a porous silica layer at impact velocities between 0.1 and 80 m s−1

To study the accretional growth of rimmed chondrules and their agglomerates in the solar nebula, we measured the restitution coefficients, ε, and the sticking velocities to a porous silica layer, v_c, by impacting the silica layer with a glass ball at velocities from 0.1 to 80 m s^?1. We used a porous silica layer covering a basalt block with thicknesses ranging from 1/5 of the glass ball radius to equal to the glass ball radius as a rimmed chondrule analogue, and the porosity of the silica layer was set to be 70%, 80%, 85%, and 90%. Collisional experiments were conducted by means of the free fall method or by the use of a spring gun or a gas gun, allowing us to vary the impact velocity. We used a laser displacement meter to estimate the impact and rebound velocities as well as the acceleration during the collision at impact velocities below 1 m s^?1. As a result, the sticking velocity, v_c, of 90%- and 85%- porosity layers with a thickness equal to 1/2 of the glass ball diameter was 0.44 and 2.4 m s^?1, respectively. On the other hand, we found a distinct barrier to sticking for smaller-porosity layers: the silicate layer with a porosity smaller than 80% never exhibited sticking at any impact velocity below 1 m s^?1. Instead, we observed a rebound effect with restitution coefficients larger than 0.2. In the case of a silica layer with a porosity smaller than 80%, we observed the sub-sticking condition defined by ε < 0.1 at velocities extending from 5 m s^?1 to 70 m s^?1.     

Shock ionization of line-emitting gas in the radio galaxy PKS 0349−27

The FR II radio galaxy PKS 0349−27 contains a luminous emission-line nebula, extending over several tens of kpc around its host galaxy. We investigate the spatial distribution of the kinematics, line ratios and total emission-line flux of the gas by means of a detailed series of long-slit spectra that cover its entire extent. We show that the physical properties of the line-emitting gas, in particular its ionization properties, excitation state, dynamics and energetics, suggest a scenario involving auto-ionizing shocks as the dominant ionization mechanism.     

Chinese Journal of Astronomy and Astrophysics

An international bimonthly journal, founded in 2001 as a continuation of Acta Astrophysica Sinica (founded in 1981, ISSN 0253-2379). The Chinese Journal of Astronomy and Astrophysics (ISSN 1009-9271) is published for the Chinese Astronomical Society and the National Astronomical Observatories of Chinese Academy of Sciences by the Science Press in Beijing.     

Spectrum and anisotropy of cosmic rays at TeV–PeV-energies and contribution of nearby sources

The role of nearby galactic sources, the supernova remnants, in formation of observed energy spectrum and large-scale anisotropy of high-energy cosmic rays is studied. The list of these sources is made up based on radio, X-ray and gamma-ray catalogues. The distant sources are treated statistically as ensemble of sources with random positions and ages. The source spectra are defined based on the modern theory of cosmic ray acceleration in supernova remnants while the propagation of cosmic rays in the interstellar medium is described in the frameworks of galactic diffusion model. Calculations of dipole component of anisotropy are made to reproduce the experimental procedure of “two-dimensional” anisotropy measurements. The energy dependence of particle escape time in the process of acceleration in supernova remnants and the arm structure of sources defining the significant features of anisotropy are also taken into account. The essential new trait of the model is a decreasing number of core collapse SNRs being able to accelerate cosmic rays up to the given energy, that leads to steeper total cosmic ray source spectrum in comparison with the individual source spectrum. We explained simultaneously the new cosmic ray data on the fine structure of all particle spectrum around the knee and the amplitude and direction of the dipole component of anisotropy in the wide energy range 1 TeV–1 EeV. Suggested assumptions do not look exotic, and they confirm the modern understanding of cosmic ray origin.     

Lineaments on the Surface of the Consolidated Material of the Comet 67P/Churyumov−Gerasimenko Nucleus

Morphologic analysis of the fragments (500 × 500 pixels) of images of comet 67P/Churyumov? Gerasimenko obtained with the OSIRIS camera for 18 regions, where the consolidated material is exposed on the surface, has been carried out. In terms of resolution, the images form a series from 0.04 to 1.29 m/pixel; consequently, the areas covered by these fragments vary from 400 to ~400000 m². In all of the regions, lineaments resembling tension fractures—several dozens of structures per region—are seen; and their number scarcely changes when passing from high-resolution images to lower-resolution ones. It is clear that relatively small lineaments cease to be reliably distinguished when the image resolution worsens, but the largest and well-defined ones remain observable, while the number of larger lineaments grows proportionally to the survey area increasing. Undoubtedly, this is an observational effect, which was demonstrated by examples with an artificially worsened resolution. However, on the other hand, this means that the tension fractures of the consolidated nucleus material represent a hierarchic population of smaller (meters long) to larger (decameters and longer) features. The lineaments seen in the analyzed fragments of images were counted, their lengths were measured, and the spacings (the mean distances between lineaments) and, from them, the depths of penetration of fractures into the nucleus material were estimated. It has been shown that the mean length of lineaments within each studied region depends on its area (which here correlates with the image resolution) and the depths of fracture penetration into the nucleus body depends on the mean length of lineaments. Both dependences are close to a power law. In the images of four regions covering the areas from 100000 to 400000 m² with a resolution of 0.66?1.29 m/pixel, the structures that look like layering or sheet jointing are seen in addition to fracture lineaments. The tension fractures are apparently formed due to seasonal and diurnal variations of the temperature, while the nature of the formation of the layer-like structures is not yet fully understood.