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The paper presents the results of investigation of dynamical behaviour of known SOHO comets, assuming their orbits to be near-parabolic. Their parabolic orbits derived from the coronographs data covering short near perihelion part of the orbits are not precisely determined and it is possible to make assumption about their near parabolic eccentricities. Sungrazing comets discovered from the Earth with better determined orbits support this idea, too. The long-term numerical integrations of the model SOHO comets with the near parabolic eccentricities show periodical changes of their eccentricities, inclinations and perihelion distances. Majority of their revolution around the Sun pass within the space behind the Mars orbit. Some of these bodies come periodically to the vicinity of the inner planets.

We investigated the motion of the perijove and ascending node of the 8th satellite of Jupiter, Pasiphae. The main perturbations by the Sun on the satellite permitted to use an intermediate orbit obtained by approximated solutions of differential equations previously transformed by the Von Zeipel method. The orbit is a non-Keplerian ellipse. The secular motion of the ascending node, argument of perijove, and essential periodic perturbations were taken into account. Using our theory we showed that the inclination and eccentricity of Pasiphae can acquire values by which the orbit becomes a librating one; but, within Pasiphae's observation period, the motion of its perijove is circulating. Taking into account the results of our previous works on Pasiphae motion, we can conclude that the mean motion of the ascending node is similar for different values of the satellite inclination and eccentricity. But the mean motion of the perijove strongly depends on the orbit inclination and eccentricity, according to the Lidov-Kozai mechanism. [ABSTRACT FROM AUTHOR]

Aims. The asteroid 2015 BZ509 is the first asteroid confirmed to be in retrograde co-orbit resonance (or 1/−1 resonance) with the giant planets in the solar system. While Saturn is the only giant planet whose trojans have not yet been discovered, we identify some small bodies among centaurs and damocloids that are potentially in 1/−1 resonance with Saturn in the present study. Methods. We integrate numerically the motion of the 1000 clones (including the nominal orbit) of each centaur whose orbit has a semi-major axis between 9.3 au and 9.8 au and an inclination i > 90°. To confirm and evaluate the 1/−1 resonant configurations mentioned above, we introduce a useful one degree integrable approximation for planar 1/−1 resonance. Results. We identify four candidates potentially in 1/−1 resonance with Saturn. The capture of candidates in this particular resonant state during the 40 000 yr integration time span is very common for 2006 RJ2 (906/1000 clones), 2006 BZ8 (878/1000 clones), and 2017 SV13 (998/1000 clones), and it is less likely for 2012 YE8 (426/1000 clones). According to our statistical results, 2006 RJ2 is the best candidate to be currently in a 1/−1 mean motion resonance with Saturn, and 2017 SV13 is another important potential candidate. Moreover, 2012 YE8 and 2006 BZ8 are also centaurs of interest but their current and long-term 1/−1 resonant state with Saturn is less likely. The proportions of the clones captured in the relative long-term stable co-orbit resonance (over 10 000 yr) are also given. The motions of the 2006 RJ2, 2015 BZ509, and 2006 BZ8 in the solar system are just around the ideal equilibrium points of the 1/−1 resonance given by the planar semi-analytical model. Conclusions. Small bodies in retrograde co-orbit resonance with giant planets may be more common than previously expected. Identification of these potential mysterious minor bodies encourages the search for such objects on a larger scale in our solar system. The findings of this paper are also useful for understanding the origin and dynamical evolution of centaurs and damocloids on retrograde orbits. [ABSTRACT FROM AUTHOR]

The outbursts of comets, sudden large increases in their luminosity, are still very interesting and mysterious signs of activity of this celestial bodies. Most of the cometary outbursts are taking place at heliocentric distances where sublimation of water ice plays an important role in the activity of comets. However, the phenomenon is also observed far away from the Sun (i.e. ≃5-20 au) where the sublimation of water ice is negligible and the activity of comets is dominated by more volatile chemicals. Not only typical comets show 'cometary-like' activity but also Centaurs. In addition to the long-term changes in brightness related to heliocentric distances and short-periodic variations connected with the rotation of the nucleus, they also exhibit a random variations in luminosity which are similar to the cometary outbursts. Paper presents an overview of the most likely hypotheses and models which try to explain this phenomenon. [ABSTRACT FROM AUTHOR]

Comets have three known reservoirs: the roughly spherical Oort Cloud (for long-period comets), the flattened Kuiper Belt (for ecliptic comets), and, surprisingly, the asteroid belt (for main-belt comets). Comets in the Oort Cloud were thought to have formed in the region of the giant planets and then placed in quasi-stable orbits at distances of thousands or tens of thousands of AU through the gravitational effects of the planets and the Galaxy. The planets were long assumed to have formed in place. However, the giant planets may have undergone two episodes of migration. The first would have taken place in the first few million years of the Solar System, during or shortly after the formation of the giant planets, when gas was still present in the protoplanetary disk around the Sun. The Grand Tack (Walsh et al. in Nature 475:206-209, ) models how this stage of migration could explain the low mass of Mars and deplete, then repopulate the asteroid belt, with outer-belt asteroids originating between, and outside of, the orbits of the giant planets. The second stage of migration would have occurred later (possibly hundreds of millions of years later) due to interactions with a remnant disk of planetesimals, i.e., a massive ancestor of the Kuiper Belt. Safronov (Evolution of the Protoplanetary Cloud and Formation of the Earth and the Planets, ) and Fernández and Ip (Icarus 58:109-120, ) proposed that the giant planets would have migrated as they interacted with leftover planetesimals; Jupiter would have moved slightly inward, while Saturn and (especially) Uranus and Neptune would have moved outward from the Sun. Malhotra (Nature 365:819-821, ) showed that Pluto's orbit in the 3:2 resonance with Neptune was a natural outcome if Neptune captured Pluto into resonance while it migrated outward. Building on this work, Tsiganis et al. (Nature 435:459-461, ) proposed the Nice model, in which the giant planets formed closer together than they are now, and underwent a dynamical instability that led to a flood of comets and asteroids throughout the Solar System (Gomes et al. in Nature 435:466-469, ). In this scenario, it is somewhat a matter of luck whether an icy planetesimal ends up in the Kuiper Belt or Oort Cloud (Brasser and Morbidelli in Icarus 225:40-49, ), as a Trojan asteroid (Morbidelli et al. in Nature 435:462-465, ; Nesvorný and Vokrouhlický in Astron. J. 137:5003-5011, ; Nesvorný et al. in Astrophys. J. 768:45, ), or as a distant 'irregular' satellite of a giant planet (Nesvorný et al. in Astron. J. 133:1962-1976, ). Comets could even have been captured into the asteroid belt (Levison et al. in Nature 460:364-366, ). The remarkable finding of two 'inner Oort Cloud' bodies, Sedna and 2012 $\mbox{VP}_{113}$, with perihelion distances of 76 and 81 AU, respectively (Brown et al. in Astrophys. J. 617:645-649, ; Trujillo and Sheppard in Nature 507:471-474, ), along with the discovery of other likely inner Oort Cloud bodies (Chen et al. in Astrophys. J. Lett. 775:8, ; Brasser and Schwamb in Mon. Not. R. Astron. Soc. 446:3788-3796, ), suggests that the Sun formed in a denser environment, i.e., in a star cluster (Brasser et al. in Icarus 184:59-82, , 191:413-433, , 217:1-19, ; Kaib and Quinn in Icarus 197:221-238, ). The Sun may have orbited closer or further from the center of the Galaxy than it does now, with implications for the structure of the Oort Cloud (Kaib et al. in Icarus 215:491-507, ). We focus on the formation of cometary nuclei; the orbital properties of the cometary reservoirs; physical properties of comets; planetary migration; the formation of the Oort Cloud in various environments; the formation and evolution of the Kuiper Belt and Scattered Disk; and the populations and size distributions of the cometary reservoirs. We close with a brief discussion of cometary analogs around other stars and a summary. [ABSTRACT FROM AUTHOR]

The new échelle spectrograph FLECHAS (Fibre Linked ECHelle Astronomical Spectrograph) is in operation at the Nasmyth-focus of the 0.9 m telescope of the University Observatory Jena. FLECHAS is equipped with a sensitive back-illuminated and midband coated CCD-detector, as well as with a calibration unit for flatfield and wavelength-calibration. The spectrograph covers the spectral range between about 3900 and 8100 Å and exhibits a resolving power of R ∼ 9300. In this article all technical characteristics of FLECHAS are described and examples of the first astronomical observations obtained with the new instrument in July 2013 at the University Observatory Jena are presented, among them the first light spectra taken with FLECHAS, simultaneous imaging and spectroscopic observations, the determination of the detection limit of the instrument, the spectroscopy of stars of different spectral types and of faint extended objects, as well as the Li-line detection in the spectra of young solar-like stars. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Photometric measurements of photographic images of comet C/1987 P1 Bradfield have been carried out with a flat-bed scanner equipped with a slide module. Lengthwise and transverse photometric profiles of the cometary plasma tail have been obtained. Magnetic field induction and some other physical characteristics of the cometary plasma tail observed in November 1987 have been estimated with the use of the diffusion model for a cometary tail by Shul'man and Nazarchuk (1968). It has been shown that the scanned images of comets can be used for estimating the physical characteristics of cometary tails. [ABSTRACT FROM AUTHOR]

The origin of Jupiter-family comets is linked to the intermediate stage of evolution through the Centaur region. Thus the structure of the Centaur population provides important constraints on sources of short-period comets. We show that our model of the Oort cloud evolution gives results which are consistent with the orbital distribution of observed Centaurs. In particular, it explains the existence of the large population of Centaurs with semimajor axes greater than 60 AU. The main source for these objects is the inner Oort cloud. Both Jupiter-family and Halley-type comets are produced by Centaurs originating from the Oort cloud. The injection rate for Jupiter-family comets coming from the inner Oort cloud is, at least, not less than that for a model based on the observed sample of high-eccentricity trans-Neptunian objects. [ABSTRACT FROM AUTHOR]

This paper discusses measured textures, porosity, chemical compositions and the minerals of interplanetary dust and meteorites from primitive planetesimals and how this information can be used to explain some of the observed physical and chemical properties of meteor phenomena. [ABSTRACT FROM AUTHOR]

According to the classical theory of equilibrium figures, surfaces of equal density, potential and pressure concur (let us call them isobars). Isobars can be represented by means of Liapunov power series in small parameter q, up to the first approximation coinciding with the centrifugal to gravitational force ratio at the equator. Liapunov has proved the existence of the universal convergence domain: the above mentioned series converge for all bodies (satisfying a natural condition that the density ρ decreases from the center to the surface) if |q| < q *. Using Liapunov’s algorithm and symbolic manipulation tools, we have found q* = 0.000370916. Evidently, the convergence radius q* may be much greater in common situations. To comfirm it it is reasonable to consider two limiting and one or two intermediate cases for the density behaviour: ρ is a constant, the Dirac’s δ-function, linear function of the distance from the center, etc. And indeed, in the previous paper we find a three orders of magnitude greater value for homogeneous figures. In the present paper we find that in the opposite case of Huygens–Roche figures (a point-mass surrounded by a weightless atmosphere) the convergence radius is unexpectedly large and coincides with the well-known biggest possible value q* = 0.541115598 for such a class of figures. To ascertain it we ought to use numerical calculations, so our main result is demonstrated by means of a computer assisted proof. [ABSTRACT FROM AUTHOR]

We consider the motion of uncharged dust grains of arbitrary shape including the effects of electromagnetic radiation and thermal emission. The resulting relativistically covariant equation of motion is expressed in terms of standard optical parameters. Explicit expressions for secular changes of osculating orbital elements are derived in detail for the special case of the Poynting–Robertson effect. Two subcases are considered: (i) central acceleration due to gravity and the radial component of radiation pressure independent of the particle velocity, (ii) central acceleration given by gravity and the radiation force as the disturbing force. The latter case yields results which may be compared with secular orbital evolution in terms of orbital elements for an arbitrarily shaped dust particle. The effects of solar wind are also presented. [ABSTRACT FROM AUTHOR]

For the orbits with low to moderate inclination and eccentricity, in the asteroid main belt, the analytically computed proper elements are accurate to a level very close to the best result achievable by any analytical theory. This fundamental limitation results from the infinite web of resonances and because of the occurrence of chaotic motions. Still, there are some regions of the belt in which these proper elements are of degraded accuracy, thus preventing a reliable definition of asteroid families and detailed studies of the dynamical structure. We have used a different method to compute asteroid proper elements, following the approach introduced in the LONGSTOP project to describe the secular dynamics of the major outer planets. By applying purely numerical techniques, we produced so-called ‘synthetic’ proper elements for a catalog of 10,256 asteroids with osculating semimajor axes between 2.5 and 4.0 AU. The procedure consisted of simultaneous integration of asteroid and planetary orbits for 2 Myr, with online filtering of the short-periodic perturbations. The output of the integration was spectrally resolved, and the principal harmonics (proper values) extracted from the time series. For each asteroid we have also tested the accuracy and stability in time of the proper elements, and estimated the maximum Lyapunov Characteristic Exponent to monitor the chaotic behaviors. This provided information on the reliability of the data for each orbit, in particular allowing to select 1,852 cases for an extended integration (10 Myr) of the orbits showing instability. The results indicate that for more than half of the cases the proper elements have a time stability improved by more than a factor 3 with respect to the elements computed by the previous analytical theory. But of course there are also unstable cases for which the proper elements are less accurate and reliable, the extreme examples being 23 orbits exhibiting hyperbolic escape from the solar system. This form of escape from the asteroid belt could be responsible for a significant mass loss over the age of the solar system. [ABSTRACT FROM AUTHOR]

Long-period (LP) comets, Halley-type (HT) comets, and even some comets of the Jupiter family, probably come from the Oort cloud, a huge reservoir of icy bodies that surrounds the solar system. Therefore, these comets become important probes to learn about the distant Oort cloud population. We review the fundamental dynamical properties of LP comets, and what is our current understanding of the dynamical mechanisms that bring these bodies from the distant Oort cloud region to the inner planetary region. Most new comets have original reciprocal semimajor axes in the range2 × 10-5 < 1/aorig < 5 × 10-5AU-1. Yet, this cannot be taken to represent the actual space distribution of Oort cloud comets, but only the region in the energy space in which external perturbers have the greatest efficiency in bringing comets to the inner planetary region. The flux of Oort cloud comets in the outer planetary region is found to be at least several tens times greater than the flux in the inner planetary region. The sharp decrease closer to the Sun is due to the powerful gravitational fields of Jupiter and Saturn that prevent most Oort cloud comets from reaching the Earth’s neighborhood (they act as a dynamical barrier). A small fraction of ∼10-2 Oort cloud comets become Halley type (orbital periods P < 200 yr), and some of them can reach short-period orbits with P < 20 yr. We analyze whether we can distinguish the latter, very ‘old” LP comets, from comets of the Jupier family coming from the Edgeworth-Kuiper belt. [ABSTRACT FROM AUTHOR]

We present a comprehensive analysis of the dynamics of Veritas family members located in a chaotic strip centeredat 3.174 AU. A total of 600 chaotic members of the family and their clones were integrated for 100 Myr, and the variation of the distance with respect to the barycenter of the family have been computed forall of them. A simple classification of the prevailing behaviors hasbeen introduced to help identify typical dynamical patterns and states that could affect an estimate of the upper bound to the age of the family. We pointed out the importance of the temporary captures in thequasi-stable states, which occur often enough to affect the statistical analysis of the exits. The results are compatible with the young age (<100 Myr) for the family of Veritas, but we cannot say precisely how young it really is. [ABSTRACT FROM AUTHOR]

Ice is a protonic conductor, as has been demonstrated many times by electrolysis experiments. The dirty ices which comprise the thick (∼10[sup 3] km) crusts of several distant moonlike bodies are subjected to bulk electrolysis by currents excited by the motion of such bodies in cosmic magnetic fields (for example, Voyager-1 measured a current amounting to ∼10[sup 7] A flowing through the Jovian satellite Io and its surroundings). The accumulation of electrolysis products in ice in amount equal to 10–15 wt. % renders such a solid solution capable of detonation. Global explosions of the crusts of moonlike bodies account for the origin and the known properties of many asteroids, short-period comets, planetary rings and small satellites, the formation of Titan’s atmosphere, the differences between Jupiter’s Galilean satellites, etc. Many predictions made on this basis have already been confirmed, and others are awaiting testing. According to all the signs, only the ices of the fourth Galilean satellite Callisto have not yet exploded. If they explode, the Earth will be subjected to concentrated bombardment by cometary nuclei, which will create a “nuclear winter” once every 60 years on the average. Therefore, a very high priority should be assigned to in situ investigations of Callisto for the purpose of determining the degree of saturation of its ices with electrolysis products. © 1999 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The Institute of Theoretical Astronomy in St. Petersburg and the Astronomical Institute in Bratislava are preparing a new edition of the Catalogue of short-period comets. This edition will be supplemented by short-period comets discovered after the year 1983 and comprises some new features, e. g. the evolution of orbital elements between the years 1750 and 2050, and the perihelion passages of comets within the 1994-2050 years. A new method has been employed for the determination of nongravitational parameters from the osculating elements of a comet based on all its observed returns. The method has been tested on the comets P/Comas Solá and P/Forbes with all returns, except the last one. The results have been compared with the osculating elements of the last return and those used in the old edition of the Catalogue of short-period comets. The new method enables a good prediction of osculating elements for the future, at least for the next return. [ABSTRACT FROM AUTHOR]