Affordable échelle spectroscopy with a 60 cm telescope

A new fiber‐fed spectrograph was installed at the 60 cm telescope of the Stará Lesná Observatory. The article presents tests of its performance (spectral resolution, signal‐to‐noise ratio, radial‐velocity stability) and reports observations of selected variable stars and exoplanet host stars. First test observations show that the spectrograph is an ideal tool to observe bright eclipsing and spectroscopic binaries but also symbiotic and nova‐like stars. The radial‐velocity stability (60–80 m s^–1) is sufficient to study spectroscopic binaries and to detect easily the orbital motion of hot‐Jupiter extrasolar planets around bright stars. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Étude du système AX Mon

We have divided this investigation into four main parts. In the first part, we study the ways in which the envelope affects the composition and the spectral variations, and the orbital motion acts on the envelope absorption intensities and how the extent of the envelope constantly decreases during the 11 yr of our observations. This phenomenon regarding AX Mon has not been previously reported in the literature. However, it explains the appearance of the α Cygni spectrum which occurs according to an arbitrary integral multiple of the orbital periods. Two absorbing envelopes seem to exist: an exterior shell of hydrogen and an interior metallic shell, which appears only when the last hydrogen line of the Balmer series of the envelope is H 27. In the second part, the study of the line Feii λ 4233 shows the influence of the orbital motion on the profile and, in particular, its effect on the absorption in the envelope. The decrease of the extent of the envelope is shown by means of a series of ‘isophase curves’, which indicates that there is maximum emission whenever, there is maximum envelope extension. The existence of satellite components to the red or violet gives evidence for the existence of heterogeneous velocity layers, contracting more rapidly than the bulk of the envelope during the cycle 100 and expanding more rapidly during cycle 116. The study of theV/R ratio shows that this ratio is independent of the orbital motion and always remains bigger than one. Some layers fall down to the photosphere as the envelope decreases (cycle 100 to 108). These layers participate in the general motion of the envelope (cycles 109 to 112) and then are strongly accelerated towards the border when the general contraction in the envelope increases again (cycles 112 to 116). The nature of the radial velocities indicates a pulsation of the emission layers which is connected with the orbital motion. The direction of the acceleration in the internal layers is reversed from apastron to periastron, while at the same time the acceleration of the internal layers increases. These motions cause changes in the density which could explain the variations of intensity in the spectrum of the envelope. In the third part, we study the photometric variations referring to three time-scales:

1. very short time-scale variations (≤4 hr). These variations can be important, reaching 0.1 mag, and can be described by a model matter ejection in very hot gaseous streams.
2. short time-scale variations (>1 day). These variations are connected with the intensity of the satellite absorptions of the line Feii λ 4233 and could be interpreted as absorption variations in the low layers of the envelope.
3. long time-scale variations (≤3 yr). We observe a perceptible decrease of the amplitude of (b) type variations, but no change in their mean value. We can then determine the AX Mon indices (V=6.77;B?V=+0.33;U?B=?0.66). The amplitude of the variations seems to increase as the envelope increases.

In the fourth part, we show that the spectral type of the hotter star can be estimated to be B0.5 V and for the cold star to be K2 II. The mass-ratio is estimated by choosing the velocity curve of the α Cygni spectrum to represent the B star, this choice leading to results which agree very well with the observations. In the resulting model, the secondary star fills the Roche's lobe and mass exchange can occur between the K star and the B star. The large value of the inclination (i=79°) leads to a quasiequatorial observation and explains why, in spite of the small eccentricity, we can observe tidal effects and the resulting spectral changes. The study of the evolution of the system by means of the theories by Crawford and Plavec shows that the mass exchange began with the commencement of nuclear reactions at the border of the B star. During this evolution, the role of the two components has changed, the original primary becoming the secondary. In this assumption, the present system has exchanged about half of the permitted mass. The emissive zone radius is estimated to be 70R _⊙ by means of Sobolev's theory. This zone is entirely contained within the Roche's lobe of the star and is very sensitive to the gravitational action of the K star.     

Long‐slit échelle spectroscopy of galactic outflows: The case ofNGC 4449

At high redshift the ubiquity of outflows and winds in strongly star‐forming galaxies has been demonstrated using rest frame UV absorption lines. In the cases with optical emission lines, the studies mostly had to rely on low and intermediate dispersion spectra. This implies that for detailed studies of galactic wind physics we have to use local objects. In particular, dwarf galaxies are well suited to extrapolation to high redshift protogalaxies. Several kinematic studies of strongly starforming dwarf galaxies using Fabry‐Pérot and IFU spectrographs exist. Unfortunately, similar as for high redshift galaxies the employed spectral resolution is often significantly higher that the thermal line width. As a result faint high velocity features and details of the turbulent motion are hidden or unresolved. Here we will present an analysis of the ionized gas kinematics of the prototypical star‐forming irregular galaxy NGC 4449 using long‐slit, high‐dispersion échelle spectra. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Cas spécials du problème des deux corps solides

Resume Il est envisagé dans ce travail deux cas spécials du problème du mouvement translatoire-rotatoire des deux corps solides. Dans le premier cas les particules élémentaires des deux corps quelconques s' agissent par la force, proportionnele au premier degré de la distance mutuelle. Dans le second cas les particules élémentaires des deux sphéres, possedant la structure sphérique, s'agissent par la force, proportionnele a quelque degré de la distance. Dans l'un et l'autre cas le mouvement translatoire ne dépend du mouvement rotatoire et les équations differentielles correspondantes s'intégrent par les quadratures.

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Special cases in the problem of two rigid bodies

In the present paper two special cases in the problem of two rigid bodies is examined. In the first case two arbitrary bodies interact with forcee, proportional to first degree of distance. In the second case two spheres interact with force, proportional to some degree of distance. In the both cases the translatory motion not depend from the rotatory motion and the differential equations integrate by quadratures.

     

On self–killing and self–creating dynamos

Numerical studies with a spherical dynamo model have shown two remarkable phenomena. The model consists of a spherical body of an electrically conducting incompressible uid surrounded by free space. In addition to a rotation of the body an inner motion due to a given forcing is considered which satisfies a no–slip condition at the boundary. The full interaction of magnetic field and motion is taken into account. Starting from a fluid motion capable of dynamo action and a very weak magnetic field it was observed that the growing magnetic field destroys the dynamo property of the motion and then decays, and that the system ends up in a state with another motion incapable of dynamo action and zero magnetic field. In another case with a motion unable to prevent small magnetic fields from decay it proved to be possible that stronger magnetic fields deform it so that a dynamo starts to work which enables the system to approach a steady state with a finite magnetic field.     

Mariner 9: An instrument of dynamical science

We review and evaluate the contributions of Mariner 9 in improving our knowledge of the dynamical characteristics of Mars and its two satellites, Phobos and Deimos. Primary results include the discovery of the large gravitational and topographical bulge in the Tharsis region, the development of a detailed gravity model representable as coefficients in a spherical harmonic expansion, the development of a topographic model exhibiting a three kilometer displacement of the center of figure from the center of mass, and the determination of the size, shape and motion of Phobos and Deimos.     

Oscillation phenomena in the galactic bulge X-ray source GX 9 + 1

Analyzing the observational data of the galactic bulge X-ray source GX 9 + 1 we found oscillations on the scale of hundreds of seconds to be present. This result should help our understanding of the accretion properties and orbital motion of this low-mass, X-ray binary.     

Eléments orbitaux corrigés de l'étoile double visuelle ADS 9626 BC—STF 1938

Orbital elements of the visual binary star ADS 9626 BC are given. The dynamical parallax and total mass of the system have been calculated.     

Photometric study of 9 doubtful open clusters

We present results of a photometric investigation of 9 poorly studied apparent open clusters. While the aim of our survey was to determine structural and astrophysical parameters for these objects, they were found not to be physical groups of stars. BV wide‐field CCD photometry combined with the near‐infrared JHK_S data from the 2MASS and proper motions were used to study their nature. Detailed analysis of radial density profiles, morphology of decontaminated colourmagnitude diagrams, and proper motion distributions indicate that these stellar ensembles are projective chance alignments of physically unrelated stars. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dynamical evolution of Earth’s quasi-satellites: 2004 GU9 and 2006 FV35

We study the dynamical evolution of Asteroids (164207) 2004 GU₉ and 2006 FV₃₅, which are currently Earth quasi-satellites (QS). Our analysis is based on numerical computation of their orbits, and we also applied the theory of co-orbital motion developed in Wajer (Wajer, P. [2009]. Icarus 200, 147-153) to describe and analyze the objects’ dynamics. 2004 GU₉ stays as an Earth QS for about a 1000 years. In the present epoch it is in the middle of its stay in this regime. After leaving the QS orbit near 2600 this asteroid will move inside the Earth’s co-orbital region on a regular horseshoe (HS) orbit for a few 1000 years. Later, either HS-QS or HS-P transitions are possible, where P means “passing”. Although 2004 GU₉ moves primarily under the influence of the Sun and Earth, Venus plays a significant role in destabilizing the object’s orbit. Our analysis showed that the guiding center of 2006 FV₃₅ moves deep inside the averaged potential well, and since the asteroid’s argument of perihelion precesses at a rate of approximately , it prevents the QS state begin left for a long period of time; consequently the asteroid has occupied this state for about 10⁴ years and will stay in this orbit for about 800 more years. Near 2800 the asteroid’s close approach with Venus will cause it to exit the QS state, but probably it will still be moving inside the Earth’s co-orbital region and will experience transitions between HS, TP (tadpole) and P types of motion.     

On Spinor Equations of Motion and their “Possible Integrals”

The motion of one point mass of the classical mechanics is treated by means of the relativistic spinor regularization (KUSTAANHEIMO 1975). Most general spinor equations of motion (2.9)‒(2.10)and the differential equations(3.16)‒(3.25)for the “possible integrals” (3.2)‒(3.11)of these quations of motion are deduced. If the force is a superposition of a conservative central force and of another force perpendicular to radius vector and velocity (Chapter 4, Case D), then the theory yields scalar and spinor integrals (4.7), (4.10)‒(4.12), (4.14)‒(4.15), (4.17), (4.28) that enable a parametric representation of the orbit by quadratures, as soon as one solution of a RICCATI differential equation (4.33) has been found.     

Adiabatic chaos in the Prometheus–Pandora system

The chaotic orbital motion of Prometheus and Pandora, the 16th and 17th satellites of Saturn, is studied. Chaos in their orbital motion, as found by Goldreich & Rappaport and Renner & Sicardy, is due to interaction of resonances in the resonance multiplet corresponding to the 121:118 commensurability of the mean motions of the satellites. It is shown rigorously that the system moves in adiabatic regime. The Lyapunov time (the 'time horizon of predictability' of the motion) is calculated analytically and compared to the available numerical–experimental estimates. For this purpose, a method of analytical estimation of the maximum Lyapunov exponent in the perturbed pendulum model of non-linear resonance is applied. The method is based on the separatrix map theory. An analytical estimate of the width of the chaotic layer is made as well, based on the same theory. The ranges of chaotic diffusion in the mean motion are shown to be almost twice as big compared to previous estimates for both satellites.     

The UKIDSS–2MASS proper motion survey – I. Ultracool dwarfs from UKIDSS DR4

The UK Infrared Telescope Infrared Deep Sky Survey (UKIDSS) is the first of a new generation of infrared surveys. Here, we combine the data from two UKIDSS components, the Large Area Survey (LAS) and the Galactic Cluster Survey (GCS), with Two-Micron All-Sky Survey (2MASS) data to produce an infrared proper motion survey for low-mass stars and brown dwarfs. In total, we detect 267 low-mass stars and brown dwarfs with significant proper motions. We recover all 10 known single L dwarfs and the one known T dwarf above the 2MASS detection limit in our LAS survey area and identify eight additional new candidate L dwarfs. We also find one new candidate L dwarf in our GCS sample. Our sample also contains objects from 11 potential common proper motion binaries. Finally, we test our proper motions and find that while the LAS objects have proper motions consistent with absolute proper motions, the GCS stars may have proper motions which are significantly underestimated. This is possibly due to the bulk motion of some of the local astrometric reference stars used in the proper motion determination.     

The proper motion of the neutron star RXJ1856.5‐3754 as measured by optical and X‐ray imaging

The proper motion of the faint (V = 25.6 mag) neutron star RXJ1856.5‐3754 as measured consistently with both the FORS1 optical imager on the ESO Very Large Telescope (VLT) as well as with the ROSAT High Resolution Imager is presented. With two VLT images obtained with a 0.95 year epoch difference in Apr 1999 and Apr 2000, a proper motion of μ_α = 0.326 ± 0.064″ per year to the east and no detectable motion in declination is found, consistent with simultaneous findings by Walter (2001) using three HST observations. Also, by comparing the positional differences between the strong X‐ray source RXJ1856.5‐3754 and other X‐ray sources detected in the same ROSAT High Resolution Imager field (observed in Oct 1994 and Oct 1997), a proper motion of 0.34 ± 0.12″ to the east is detected. This may be the first star, where a proper motion is clearly detected in X‐ray images. Additional VLT images taken in half‐year intervals give an upper limit to the parallax of ∼51 mas. Furthermore, in archived VLT observations, the first B‐band detection of this object is found with B = 25.14 ± 0.41 mag.     

Meteorite transport—Revisited II

In Wisdom (2017), I presented new simulations of meteorite transport from the chaotic zones associated with major resonances in the asteroid belt: the ν₆ secular resonance, the 3:1 mean motion resonance with Jupiter, and the 5:2 mean motion resonance with Jupiter. I found that the observed afternoon excess (the fact that approximately twice as many meteorites fall in the afternoon as in the morning) of the ordinary chondrites is consistent with chaotic transport from the 3:1 resonance, contradicting prior reports. Here I report an additional study of the transport of meteorites from ν₆ secular resonance and the 3:1 mean motion resonance. I use an improved integration algorithm, and study the evolution of more particles. I confirm that the afternoon excess of the ordinary chondrites is consistent with transport from the 3:1 resonance.     

The Jovian Great Red Spot — Its Three Months Oscillation

Fourier-analysis of the motion of Jupiter's Great Red Spot (GRS) yields concealed periodicities in this motion. These periodicities are possible clues for the decision in favour of one of the different models of the GRS.     

Singularite du probleme de Störmer (Singularity of Störmer's problem)

Résumé Dans un précédent travail (Eschbach, 1979, 1980, 1982), j'ai généralisé les changements de variables employés par McGehee (1974) dans l'étude de la collision triple. Le propos de cet article est d'employer les mêmes techniques pour le problème de Störmer: mouvement d'une particule chargée soumise à l'influence d'un dipôle magnétique.

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In previous papers (Eschbach, 1979, 1980, 1982). I generalised the change of variables used by McGehee in the study of the triple collision. The object of this paper is to use the same technique for Störmer's problem, which studies the motion of a charged particle under the influence of a magnetic dipole.

     

Simultaneous X-ray/optical observations of GX 9+9 (4U 1728−16)

We report on the results of the first simultaneous X-ray ( RXTE ) and optical [South African Astronomical Observatory (SAAO)] observations of the luminous low-mass X-ray binary (LMXB) GX 9+9 in 1999 August. The high-speed optical photometry revealed an orbital period of 4.1958 h and confirmed previous observations, but with greater precision. No X-ray modulation was found at the orbital period. On shorter time-scales, a possible 1.4-h variability was found in the optical light curves which might be related to the MHz quasi-periodic oscillations seen in other LMXBs. We do not find any significant X-ray/optical correlation in the light curves. In X-rays, the colour–colour and hardness-intensity diagrams indicate that the source shows characteristics of an atoll source in the upper banana state, with a correlation between intensity and spectral hardness. Time-resolved X-ray spectroscopy suggests that two-component spectral models give a reasonable fit to the X-ray emission. Such models consist of a blackbody component which can be interpreted as the emission from an optically thick accretion disc or an optically thick boundary layer, and a hard Comptonized component for an extended corona.