A dynamical study of the multiple system 17 Cygni ABFG

Adynamical study of the relative motions of the components of the inner pairs AB (ADS 12913) and FG (ADS 12889) of the quadruple heirarchical system 17 Cygni (WDS 19464+3344) is presented, as well as analysis of themotions of the outer pair AB–FG. The study is based on CCD observations obtained on the 26-inch refractor of the Pulkovo Observatory (2003–2013), position observations from the WDS catalog, Hipparcos parallaxes, and radial velocities of the components from literature data. A family of orbits for 17 Cyg AB is obtained for the first time, and has a most probable period of 6200 yrs. The apparent motion parameters (AMP) method is used, since the entire visible arc of the orbit over 1832–2013 is only ~4?. The AMP method is also used to calculate the orbit of the 17 Cyg FG pair, which has a period of 238 yrs, yielding results in good agreement with the orbits derived in other studies. The ephemerides of the obtained AMP orbits, the position data for the AF pair from the WDS catalog (11 positions during 1893–2002), and Pulkovo CCD observations for 2007–2013 are used to calculate the apparent motion parameters of AB–FG outer pair, as well as a family of close-to-parabolic orbits with periods of 3.7 million years ormore. All the orbits (for both the inner and the outer pairs) are steeply inclined to theGalactic plane. Monte Carlo simulations are used to compute the probability that the outer pair is gravitationally bound, which is 47%. The similarity of the proper motions and radial velocities of all the components provides evidence that they all belong to a single stellar stream. Data from the CNS3 catalog are used to compose a list of candidate members of this stream.     

A dynamical study of 12 wide visual binaries

We have carried out the first dynamical studies of the relative motions of the components of 12 wide binaries: ADS 497, ADS 2427 (GL 130.1), ADS 3593, ADS 5436, ADS 6646, ADS 6783, ADS 9559 (δ Boo), ADS 10329, ADS 10759 (ψ Dra), ADS 14878, ADS 15229, and ADS 16558. The analysis is based on series of photographic observations made with the 26-inch refractor of Pulkovo Observatory, supplemented by data from the WDS Catalog, radial velocities and HIPPARCOS parallaxes. We used the parameters of the apparent motions, which can yield the orbit and mass of a binary from observations over a short arc of the orbit of the order of 5°–10°. The orbits and masses for six stars with orbital periods from 500 to 20 000 years have been reliably determined. For five stars with periods from 2000 to 100 000 years, we obtained probable orbits and mass estimates. For ADS 497 and ADS 10329, the mass excesses in their systems are 1 and 3 M _⊙, respectively, relative to the masses expected from the mass-luminosity dependence. In three cases, for ADS 3593, ADS 14878, and ADS 16558, the obtained estimates of the total mass of the components are 46, 25, and 7300 M _⊙, respectively, if the parallaxes are correct. A perturbation with amplitude 0.3″ and period 40 yrs has been detected in the orbital motion of the system ADS 10759, possibly indicating the presence of an invisible satellite with a mass of the order of 0.4 M _⊙. The orientations of the orbits in the Galactic reference frame have been determined for all 12 binaries. The planes of most of the obtained orbits are steeply inclined to the plane of the Galaxy, as was noted in previous studies.     

Orbits of the visual binaries ADS 8814 and ADS 8065 from observations along a short arc

The orbits of the visual binaries ADS 8814 and ADS 8065 are determined for the first time. The orbits were calculated using the parameters of the apparent motion, based on position observations along short arcs obtained on the 26-inch refrector of the Pulkovo Observatory, supplemented with radial-velocity observations for the stellar components in both pairs obtained on the 1-m telescope of the Simeiz Section of the Crimean Astrophysical Observatory. All previous visual and photographic observations of these stars after 1832 were also taken into account. The orbit of ADS 8814 was refined using the differential-correction method. The orbital periods of these two stars are about 800 and 6000 years, respectively. The mass estimates derived for the known parallaxes from the Hipparcos catalog correspond to the spectral types of these stars. The polar vectors of the obtained orbits in Galactic coordinates are also given.     

A dynamical study of the wide hierarchic triple star ADS 10288

We have performed the first dynamical study of the relative motions of the components of the wide hierarchic triple star system ADS 10288 (GL 649.1 = WDS 16579+4722), based on a 15-year series of photographic observations with the 26″ Pulkovo refractor, supplemented with data from the WDS catalog, HIPPARCOS parallaxes, and radial velocities of the components. The radial velocities were measured in Simeiz using the ILS stellar radial-velocity correlation spectrometer designed by A.A. Tokovinin. We applied the parameters of the apparent motion technique, which makes it possible to derive a binary’s orbit and mass from observations of a short arc, about 5°–10° in length. We derived preliminary orbits for the pairs AB and (AB)-C, whose orbital periods are 340 and 64 000 years, respectively. Mass estimates derived from the mass-luminosity relation are consistent with our dynamical estimates. We determined the orientation of the orbits in Galactic coordinates. The orbital planes are not coplanar, and are steeply inclined to the Galactic plane, as was the case in our earlier studies for most wide visual pairs we have studied.     

Orbits of four visual binaries determined from observations along short arcs

The orbits of the four visual binaries ADS 246 (GL 15), ADS 7724 (γ Leo), ADS 10386 (GJ 659), and ADS 14909 (1 Peg) have been determined using the apparent motion parameters (AMP) method. The orbital periods of these stars are 1200, 550, 7500, and 18 000 yr, respectively. The orbits were calculated based on observations along short arcs obtained with the 26-inch refractor of the Pulkovo Observatory and Hipparcos parallaxes, supplemented with radial-velocity measurements for the components of these pairs taken from the literature. All visual and photographic observations of these stars after 1830 from the WDS catalog have been taken into consideration. The new orbits of ADS 246 and ADS 7724 are compared with the orbits computed in other studies. The orbits of ADS 10386 and ADS 14909 have been determined for the first time. The orientation of the planes of the computed orbits in Galactic coordinates have also been calculated.     

Accurate relative positions and motions of poorly studied binary stars

We have studied the relative motions of the components of 25 visual binary and multiple stars for which only a modest number of observations of various types had accumulated due to their small relative component motions. A uniform series of photographic observations obtained over many years on the 26-inch refractor of the Pulkovo Observatory are used to calculate the parameters of the apparent relative positions and motions, which can be used for further kinematic and dynamical studies of these stars. A comparison of the relative and proper motions of the components indicates that they are physically bound. Optical components are identified in six systems??for the first time in the three systemsWDS00082+6217, ADS 830, and ADS 7361. The relative motions in ADS 861 and ADS 12925 suggest the presence of perturbing invisible companions, but this requires confirmation based on more accurate observations. The apparent motion parameters method yields a family of orbits with a minimum period of 26 000 yrs for the nearby wide visual binary Gliese 745, for which the parallax and relative radial velocity of the components are known.     

Analysis of the accuracy of prediction of the celestial pole motion

VLBI observations carried out by global networks provide the most accurate values of the precession-nutation angles determining the position of the celestial pole; as a rule, these results become available two to four weeks after the observations. Therefore, numerous applications, such as satellite navigation systems, operational determination of Universal Time, and space navigation, use predictions of the coordinates of the celestial pole. In connection with this, the accuracy of predictions of the precession—nutation angles based on observational data obtained over the last three years is analyzed for the first time, using three empiric nutation models-namely, those developed at the US Naval Observatory, the Paris Observatory, and the Pulkovo Observatory. This analysis shows that the last model has the best of accuracy in predicting the coordinates of the celestial pole. The rms error for a one-month prediction proposed by this model is below 100 microarcsecond.     

The multiple system ADS 9626: A quadruple star or an encounter of two binaries?

The parameters of the quadruple system ADS 9626 (µ Boo) are analyzed. The system consists of two double stars: the Aa pair with an angular separation of ρ = 0.08″ and the BC pair with an angular separation of ρ = 2.2″, separated by ρ = 107″ and having the same parallaxes and proper motions. Position observations with the Pulkovo 26″ refractor have yielded from direct astrometric measurements the difference in the apparent magnitudes and the component-mass ratio for the BC subsystem: Δm = 0.59 ± 0.06, M(B)/M(C) = 1.18 ± 0.02. Spectroscopy with the Russian-Turkish 1.5-m telescope has yielded the radial velocities and physical parameters of the Aa, B, and C components. Speckle-interferometric observations with the 6-m telescope of the Special Astrophysical Observatory have provided the first measurements of the magnitude difference in the close Aa subsystem: Δm = 0.46 ± 0.03 (λ = 5500 Å) and Δm = 0.41 ± 0.03 (λ = 8000 Å). The new observations are consistent with the known orbits, which were used to find the radial velocities for the centers of mass of the inner subsystems. Themotion of the outer pair, Aa-BC, is studied using the apparent motion parameters (AMP) method. It is not possible to derive an elliptical orbit for this pair; the elements of a hyperbolic orbit have been estimated. The difference of the heavy-element abundances for the Aa and BC subsystems of 0.5 dex confirms that these pairs have a different origin. This suggests that we are observing here a close encounter of two binary stars.     

Pulkovo catalog of relative positions and motions of visual double and multiple stars from photographic observations with the 26-inch refractor in 1960–2007

The results of long-term, uniform, photographic observations of visual double and multiple stars obtained on the Pulkovo 26″ refractor are presented. Relative positions are calculated for 259 pairs of visual double stars in 194 systems, with the relative motions also computed for 127 pairs. Lower limits for the total masses of the systems for which elliptical orbits possible are also found for 48 pairs with reliable parallaxes from the Hipparcos catalog. The accuracies of the three measuring machines used in the reduction of the photographic plates are compared. Component separations measured with different machines can differ by as much as 0.2″, demonstrating the advantages of using uniform observations.     

A 12-Year Periodicity in the Pulse Arrival Times for the Pulsar PSR B0943+10

An analysis of observations obtained over 26 years beginning in 1992 have indicated the appearance of sinusoidal variations with a period of about 12 years in the residual deviations of the pulse arrival times (PATs) for the pulsar PSR B0943+10. This behavior in the PAT residuals could be due to the influence of a planet orbiting the pulsar. These observations were carried out on the Large Scanning Antenna of the Pushchino Radio Astronomy Observatory at 112 MHz.

     

急倾斜软硬互层巷道变形破坏机制及支护技术研究

针对急倾斜软硬互层巷道围岩大变形控制难题,采用现场试验、理论分析和数值仿真等多种手段,研究急倾斜巷道围岩变形破坏机制,研究结果表明：急倾斜软硬互层巷道的变形与破坏具有非对称性,偏压作用明显,呈现顶板下滑,底板臌起的相互错动变形特征,底臌严重且易片帮冒顶。巷道断面与岩层倾斜方向的钝角部位受侧向约束小,因而剪切滑移变形较大,是产生非对称变形破坏的关键部位;下帮围岩变形破坏较上帮更为严重。基于急倾斜巷道的变形破坏特点,提出在锚- 网-索耦合支护的基础上利用锚索、底角锚杆等对产生差异变形破坏的关键部位进行加强支护的方法,巷道大变形得到了有效控制。     

<Emphasis Type="Italic">BV I</Emphasis><Subscript><Emphasis Type="Italic">c</Emphasis></Subscript> photometry of RR Lyrae stars

We have obtained 26 372 CCD frames in the B, V, and I _c filters for 81 RR Lyrae stars in 2008–2010, using the 76-cm telescope of the South African Astronomical Observatory and the 40-cm telescope of the Cerro Armazones Observatory, North Catholic University (Chile) using an SBIG ST-10XME CCD camera. For 12 of these RR Lyrae stars, we also obtained 337 brightness measurements in the B and V bands in 2000–2001 using the 60-cm telescope of the High Altitude Mt. Maidanak Observatory (Republic of Uzbekistan). We present tables of observations, light curves, and improved light-curve elements for all these RR Lyrae stars. The Blazhko effect was detected for SU Hor.     

A search for Keplerian periods in the brightness variations of T Tauri and Ae Herbig stars

Long-term, uniform series of U BV R observations of T Tauri and Ae Herbig stars obtained over 20 yr at the Maidanak Observatory as part of the ROTOR program are analyzed. We find a linear relationship between the characteristic variability time scale and the bolometric luminosity of the star+disk system: the higher the luminosity, the slower the brightness variations. This dependence is valid over a wide range of masses and luminosities, from T Tauri stars to Ae Herbig stars. On average, the variability time scale is one-quarter the Keplerian period at the dust-sublimation radius, which is known from interferometric observations. Some T Tauri stars have periods from 25 to 120 days, which are preserved over several observing seasons. These periods correspond to Keplerian orbits with semi-major axes from 0.14 to 0.52 AU. The results obtained provide indirect evidence for the existence of protoplanets in the gas-dust disks of stars in early stages of their evolution toward the main sequence.     

陡倾逆断层形成机制——以塔里木盆地色力布亚断层为例

中国西部盆地多发育陡倾逆冲断层,但对其成因仍未取得统一认识。色力布亚断裂带位于塔里木盆地的西部,是一条典型的陡倾逆冲断层,为研究陡倾断层的成因提供了很好的实例。根据最新地震剖面与地层分析认为,色力布亚断裂上部倾角约为65°,经两期构造运动形成,第一期是加里东晚期运动-海西早期运动（362~439 Ma）,第二期为喜马拉雅中期运动（5.3~23.3 Ma）;正是断层的多期活动形成了上部的陡倾断层,即先存缓倾逆断层的活动改变了局部应力场,使最大主应力轴由水平变倾斜,随之产生的库伦断裂倾角变陡,并伴生反冲逆断层。同时利用数字砂箱模拟结果验证了上述推断。      

Variability of the Blazar 4C 38.41 in 2006–2017

The results of multicolor photometric and polarization observations of the blazar 4C 38.41 (Q 1633+382) performed at St. Petersburg State University, the Pulkovo Astronomical Observatory of the Russian Academy of Sciences, Boston University, and Steward Observatory in 2006–2017 are analyzed. Separate variable sources responsible for the observed activity are distinguished, whose power-lawspectra and high degree of polarization confirm their synchrotron nature. The observed color variability of the object (redder when brighter) can be explained by an increase in the contribution to the total emission of a red component with variable flux and a constant relative spectral energy distribution. A close correlation between the optical and gamma-ray light curves is identified, suggesting the same location of the variable sources responsible for the radiation in these bands.

     

BVIc photometry of classical cepheids from the ASAS-3 catalog

In 2008–2010, we obtained 6095 CCD frames in the BV I _c photometric systemfor 49 classical Cepheids discovered in the ASAS-3 project. The observations were obtained on the 76-cm telescope of the South African Astronomical Observatory (SAAO, RSA) and the 40-cm telescope of the Cerro Armazones Observatory of the Catholic University of the North (OCA, Chile), with a SBIGCCD ST-10XME camera. We present tabulated observations, light curves, and revised elements for the brightness variations.     

Influence of an Inclined Rock Stratum on In-Situ Stress State in an Open-Pit Mine

In-situ stress plays a major role with respect to deformation and stability around underground or surficial excavations located at significant depth. Many sedimentary rock masses are more or less horizontally bedded. However, a possibility exists to have one or few inclined rock strata such as dikes in these horizontally bedded formations. It is important to know how the in situ stress changes from a purely horizontally bedded situation to a horizontally bedded rock mass that contains one or few inclined rock strata. This paper presents such an investigation using the largest open-pit metal mine in China—as a case study. This mine has a bedded rock mass with one steeply inclined rock stratum. For the bedded rock mass, the vertical stress was calculated based on the overburden above each lithology. The available in situ stress measurements conducted at the mine were used to estimate the ratios of horizontal to vertical stress. Numerical modeling was performed for the two scenarios: (a) the horizontally bedded system subjected to both the in situ and boundary stresses and (b) the mine lithological system that includes an inclined stiffer (denser) stratum intruding softer horizontally bedded system subjected to only boundary stresses to investigate the influence of an inclined rock stratum on the computed stress field. Thirty points were selected to compute the stresses on six planes of the inclined rock stratum. Due to the discontinuous nature of the geologic system at the interface between the stiffer inclined stratum and softer horizontally bedded system, one principal stress has become normal to the interface plane and the other two have become parallel to the interface plane with all three being perpendicular to each other. Presence of the stiffer inclined rock stratum has given rise to (a) increase in normal stresses up to about 120 % in the inclined rock stratum and (b) new shear stresses approximately in the range ?10.0 to 15.0 MPa. This means, because most of the rock masses are not purely horizontally bedded, estimation of in situ stress through measurements as well as application of in situ stress in numerical modeling associated with underground or surficial excavations located at significant depth is a difficult exercise. A better way to estimate the in situ stresses for complex geologic systems may be through application of appropriate boundary stresses to the geologic system in a numerical model.     

Variations of the Blazar AO 0235+164 in 2006–2015

The results of optical, radio, and gamma-ray observations of the blazar AO 0235+16 are presented, including photometric (BV RIJHK) and polarimetric (R)monitoring carried out at St. Petersburg State University and the Central (Pulkovo) Astronomical Observatory in 2007–2015, 43 GHz Very Long Baseline Interferometry radio observations processed at Boston University, and a gamma-ray light curve based on observationswith the Fermi space observatory are presented. Two strong outbursts were detected. The relative spectral energy distributions of the variable components responsible for the outbursts are determined; these follow power laws, but with different spectral indices. The degree of polarization was high in both outbursts; only an average relationship between the brightness and polarization can be found. There was no time lag between the variations in the optical and gamma-ray, suggesting that the sources of the radiation in the optical and gamma-ray are located in the same region of the jet.     

On the existence of planets around the pulsar PSR B0329+54

Results of timing measurements of the pulsar PSR B0329+54 obtained in 1968–2012 using the Big Scanning Antenna of the Pushchino Radio Astronomy Observatory (at 102 and 111 MHz), the DSS 13 and DSS 14 telescopes of the Jet Propulsion Laboratory (2388 MHz), and the 64 m telescope of the Kalyazin Radio Astronomy Observatory (610 MHz) are presented. The astrometric and rotational parameters of the pulsar are derived at a new epoch. Periodic variations in the barycentric timing residuals have been found, which can be explained by the presence of a planet orbiting the pulsar, with an orbital period P₁ = 27.8 yr, mass m _c sin i = 2M_?, and orbital semi-major axis a = 10.26 AU. The results of this study do not confirm existence of a proposed second planet with orbital period P₂ = 3 yr.     

A simple failure criterion for rough joints and compound shear surfaces

The subject under investigation is the strength of a single shear plane which exhibits a regular, asymmetric roughness pattern. In the shear direction the asperities are so steeply inclined that the joint becomes mechanically non-effective with the result that the asperities are sheared off. Against the shear direction the asperities are only gently inclined. It is shown that this particular roughness pattern is of some general importance in geomechanics (examples: unconfined compression test; shear plane with secondary fractures).

Simple analytical considerations allow the formulation of a shear criterion, which is dependent on friction angle ø_m and cohesionc_m of the intact rock and on the inclination γ of the gently inclined parts of the asperities which are dipping against the shear direction. In the Mohr-diagram the criterion results in envelopes which converge at high normal stresses against the envelope of intact rock. Furthermore, the criterion expresses that both the slope of the envelopes and the dilation angle continuously decrease with increasing normal stress. Therefore the criterion adequately describes features which are regarded as most important when shearing rough joints or compound shear surfaces.