Hypothetical evolutions of short-period comets

1996 ◽  
Vol 172 ◽  
pp. 213-214
Author(s):  
V. Batllo
Keyword(s):  
Solar System ◽  
Orbital Plane ◽  
Numerical Results ◽  
Outer Planet ◽  
Initial Vertex ◽  
Orbital Elements ◽  
Hypothetical Model ◽  
Short Period ◽  
Roche Limit ◽  
Short Time

The hypothetical model of capture I consider is as follows: a comet with an initial conic orbit, meets close to one of its vertices an outer planet and generates one or several little comets (crossing of the Roche limit) with an elliptic orbit. This initial vertex always remains one of the vertices of the captured orbit by the Solar System. Even if there is a discontinuity of all the orbital elements during a very short time of the capture, I assume that the orbital plane is unchanged during the capture, as indeed was the case for Brooks 2 in 1886 (see Belyaev et al., 1986) or will be for Gehrels 3 in 2300 (see Carusi et al., 1985). After this first decisive step, the “new” comets may be subject to some other captures by jovian planets during their evolution with the same scenario. All these hypotheses allow to find particular numerical results for 142 comets whose current orbital elements were found in the Marsden catalog or given by P. Rocher, but I shall only give several examples in the following section.

The Origin of the Moon and its Relationship to the Origin of the Solar System

1962 ◽  
Vol 14 ◽  
pp. 133-148 ◽  
Author(s):  
Harold C. Urey
Keyword(s):  
Solar System ◽  
The Moon ◽  
The Past ◽  
The Earth ◽  
Short Period ◽  
Origin Of The Moon

During the last 10 years, the writer has presented evidence indicating that the Moon was captured by the Earth and that the large collisions with its surface occurred within a surprisingly short period of time. These observations have been a continuous preoccupation during the past years and some explanation that seemed physically possible and reasonably probable has been sought.

Models of comets with strongly variable nongravitational effects

1999 ◽  
Vol 173 ◽  
pp. 381-387
Author(s):  
M. Królikowska ◽  
G. Sitarski ◽  
S. Szutowicz
Keyword(s):  
Cometary Nucleus ◽  
Spin Axis ◽  
Reactive Force ◽  
Orbital Elements ◽  
Cometary Nuclei ◽  
Short Period ◽  
Basic Parameters ◽  
Polar Radius ◽  
Cometary Activity ◽  
Nongravitational Effects

AbstractThe nongravitational motion of five “erratic” short-period comets is studied on the basis of published astrometric observations. We present the precession models which successfully link all the observed apparitions of the comets: 21P/Giacobini-Zinner, 31P/Schwassmann-Wachmann 2, 32P/Comas Solá, 37P/Forbes, and 43P/Wolf-Harrington. We used the Sekanina's forced precession model of the rotating cometary nucleus to include the nongravitational terms into equations of the comet's motion. Values of six basic parameters (four connected with the rotating comet nucleus and two describing the precession of spin-axis of the nucleus) have been determined along the orbital elements from positional observations of the comets. The solutions were derived with additional assumptions which introduce instantaneous changes of modulus of reactive force,Aand of maximum of cometary activity with respect to perihelion time. The present precession models impose some contraints on sizes and rotational periods of cometary nuclei. According to our solutions the nucleus of 21P/Giacobini-Zinner with oblateness along the spin-axis of about 0.32 (equatorial to polar radius of 1.46) is the most oblate among five investigated comets.

scholarly journals On the 2PN Pericentre Precession in the General Theory of Relativity and the Recently Discovered Fast-Orbiting S-Stars in Sgr A*

Universe ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 37
Author(s):  
Lorenzo Iorio
Keyword(s):  
General Theory ◽  
Present Author ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Orbital Elements ◽  
Analytical Expression ◽  
Potential Interest ◽  
Short Period ◽  
The Future ◽  
Sgr A

Recently, the secular pericentre precession was analytically computed to the second post-Newtonian (2PN) order by the present author with the Gauss equations in terms of the osculating Keplerian orbital elements in order to obtain closer contact with the observations in astronomical and astrophysical scenarios of potential interest. A discrepancy in previous results from other authors was found. Moreover, some of such findings by the same authors were deemed as mutually inconsistent. In this paper, it is demonstrated that, in fact, some calculation errors plagued the most recent calculations by the present author. They are explicitly disclosed and corrected. As a result, all of the examined approaches mutually agree, yielding the same analytical expression for the total 2PN pericentre precession once the appropriate conversions from the adopted parameterisations are made. It is also shown that, in the future, it may become measurable, at least in principle, for some of the recently discovered short-period S-stars in Sgr A*, such as S62 and S4714.

scholarly journals Resonant trans-Neptunian objects as a source of Jupiter-family comets

2006 ◽  
Vol 2 (S236) ◽  
pp. 31-34
Author(s):  
E. L. Kiseleva ◽  
V. V. Emel'yanenko
Keyword(s):  
Solar System ◽  
Dynamical Evolution ◽  
Early History ◽  
Substantial Contribution ◽  
Outer Solar System ◽  
Symplectic Integrator ◽  
Relative Fraction ◽  
Outward Transport ◽  
Short Period ◽  
History Of

AbstractThe dynamical interrelation between resonant trans-Neptunian objects and short-period comets is studied. Initial orbits of resonant objects are based on computations in the model of the outward transport of objects during Neptune's migration in the early history of the outer Solar system. The dynamical evolution of this population is investigated for 4.5 Gyr, using a symplectic integrator. Our calculations show that resonant trans-Neptunian objects give a substantial contribution to the planetary region. We have estimated that the relative fraction of objects captured per year from the 2/3 resonance to Jupiter-family orbits with perihelion distances q<2.5 AU is 0.4×10−10 near the present epoch.

The Success of Cognitive Activity of Students of the Northern (Arctic) Federal University with Different Levels of Anxietyin Different Time Conditions

2021 ◽  
Vol 18 (1) ◽  
pp. 52-59
Author(s):  
A.I. Taleeva ◽  
◽  
I.T. Madumarova ◽  
N.V. Zvyagina ◽  
◽  
...  
Keyword(s):  
Emotional State ◽  
Cognitive Task ◽  
Cognitive Activity ◽  
Whole Body ◽  
Modern World ◽  
Short Period ◽  
Personal Anxiety ◽  
Psychophysiological Testing ◽  
Short Time ◽  
Different Levels

The dynamic development of the modern world requires the processing and development of a large enough amount of information in a short period of time, which leads to a violation of the psychophysiological and psycho-emotional balance of the person. Violation of the psycho-emotional state leads to the development of increased anxiety. Students need to learn a lot of information in a very short time. The time limit affects students as a stress factor, leads to increased stress and therefore negatively affects the quality of work and in general on the whole body. The aim of the study is to determine the success of cognitive tasks by students of the Northern (Arctic) Federal University with different levels of anxiety in different time conditions. The study used a psychophysiological testing device to determine the level of situational and personal anxiety, to assess the psycho-emotional state used the technique of simple visual-motor reaction, to determine the success of the cognitive task were presented words with one missing letter.

scholarly journals How much information can be obtained from tracking the position of the leading edge in a scratch assay?

2014 ◽  
Vol 11 (97) ◽  
pp. 20140325 ◽  
Author(s):  
Stuart T. Johnston ◽  
Matthew J. Simpson ◽  
D. L. Sean McElwain
Keyword(s):  
Cell Motility ◽  
Leading Edge ◽  
Automated Image Analysis ◽  
Cell Counting ◽  
Cell Labelling ◽  
Scratch Assay ◽  
Short Period ◽  
Using Data ◽  
Short Time ◽  
Non Destructive

Moving cell fronts are an essential feature of wound healing, development and disease. The rate at which a cell front moves is driven, in part, by the cell motility, quantified in terms of the cell diffusivity D , and the cell proliferation rate λ . Scratch assays are a commonly reported procedure used to investigate the motion of cell fronts where an initial cell monolayer is scratched, and the motion of the front is monitored over a short period of time, often less than 24 h. The simplest way of quantifying a scratch assay is to monitor the progression of the leading edge. Use of leading edge data is very convenient because, unlike other methods, it is non-destructive and does not require labelling, tracking or counting individual cells among the population. In this work, we study short-time leading edge data in a scratch assay using a discrete mathematical model and automated image analysis with the aim of investigating whether such data allow us to reliably identify D and λ . Using a naive calibration approach where we simply scan the relevant region of the ( D , λ ) parameter space, we show that there are many choices of D and λ for which our model produces indistinguishable short-time leading edge data. Therefore, without due care, it is impossible to estimate D and λ from this kind of data. To address this, we present a modified approach accounting for the fact that cell motility occurs over a much shorter time scale than proliferation. Using this information, we divide the duration of the experiment into two periods, and we estimate D using data from the first period, whereas we estimate λ using data from the second period. We confirm the accuracy of our approach using in silico data and a new set of in vitro data, which shows that our method recovers estimates of D and λ that are consistent with previously reported values except that that our approach is fast, inexpensive, non-destructive and avoids the need for cell labelling and cell counting.

scholarly journals Supportive Evidence for a Brown Dwarf Solar Companion

2004 ◽  
Vol 202 ◽  
pp. 214-216
Author(s):  
John J. Matese
Keyword(s):  
Solar System ◽  
Oort Cloud ◽  
Evidence Based ◽  
Supportive Evidence ◽  
Orbital Elements ◽  
Brown Dwarf ◽  
Wide Binary ◽  
Gas Giant ◽  
Binary Object

We have previously given evidence based on Oort cloud comet orbital elements which suggested that there may be a Jovian-mass brown dwarf in our solar system. An extended cometary database is now available. The analyses have been repeated and we find that the set of statistically significant correlated anomalies is enhanced. We also respond to unsupported objections that have been raised to this conjecture. If real, the wide-binary object would constitute a natural dynamical intermediary between gas giant planetary objects and isolated objects.

scholarly journals Wolf-Rayet binaries: old friends and new acquaintances

1999 ◽  
Vol 193 ◽  
pp. 26-37 ◽  
Author(s):  
Virpi S. Niemela ◽  
Roberto Gamen ◽  
Nidia I. Morrell ◽  
Sixto Giménez Benítez
Keyword(s):  
Radial Velocity ◽  
Binary Systems ◽  
Magellanic Cloud ◽  
Elliptic Orbit ◽  
Spectral Lines ◽  
Small Magellanic Cloud ◽  
Orbital Elements ◽  
Spectroscopic Observations ◽  
Short Period ◽  
Old Friends

Observations of WR stars in binary systems are discussed, emphasizing constraints on our knowledge of the binary frequency of WR stars, and of WR stars as a distinctive class of objects. Radial velocity orbits of newly discovered binaries, e.g., WR 29, a short period WN7+OB binary in our Galaxy, and SMC/AB 7, a massive WN+O7 binary in the Small Magellanic Cloud, are presented. New spectroscopic observations of binary systems with previously known orbits are also reported, showing in the case of WR 21 evidence of change of the orbital elements as derived from different spectral lines. An elliptic orbit for CV Ser is also illustrated.

scholarly journals The Polar Fields and Time Fluctuations of the General Magnetic Field of the Sun

1971 ◽  
Vol 43 ◽  
pp. 675-695 ◽  
Author(s):  
A. B. Severny
Keyword(s):  
Magnetic Field ◽  
Close Agreement ◽  
Present Knowledge ◽  
Short Time Scale ◽  
The Sun ◽  
Statistical Nature ◽  
General Magnetic Field ◽  
Short Period ◽  
The Mean ◽  
Short Time

In an attempt to summarize the present knowledge on the general magnetic field (gmf) of the Sun we pointed out the fine structure and the statistical nature of the gmf as one of its most important properties. The dipole-like behaviour of the mean polar field strengths is combined sometimes (since 1964) with a bias of the S-polarity flux for both poles. Highly uneven distribution of gmf with latitude and longitude, the disappearance of gmf at the South pole for months, and short period, almost synchronous at both poles, variations in the sign of gmf are pointed out. The fluctuations with time of the mean magnetic field of the Sun seen as a star (as well as mf at different latitudes) shows periodicity connected with the rotation of the Sun and very close agreement with the fluctuations of the interplanetary field (sector structure). The effect of faster rotation of N-polarities as compared with S-polarities as well as the bias of mean solar as well as interplanetary S-polarity fields are also pointed out. The possibility of short time-scale (hours) intrinsic changes in the local pattern of gmf is demonstrated.

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