scholarly journals On the Planetary Orbital Period Ratio Distribution In Multiple Planet Systems

2012 ◽  
Vol 8 (S293) ◽  
pp. 110-115
Author(s):  
Ji-Wei Xie
Keyword(s):  
Solar System ◽  
Orbital Period ◽  
Theoretical Models ◽  
Observational Constraints ◽  
Ratio Distribution ◽  
Period Ratio ◽  
First Order ◽  
Exact Resonance ◽  
Statistical Effect ◽  
Mission Period

AbstractMany multiple planet systems have been found by both radial velocity (RV) and transit surveys, such as the Kepler mission. Period ratio distribution of these planet candidates show that they do not prefer to be in or near Mean Motion Resonance (MMR). Nevertheless, there are small but significant excesses of candidate pairs both spaced slightly exterior to exact resonance, particular near the first order of MMR, such as 2:1 and 3:2. Here, we first review recent observational constraints on these multiple transiting systems and theoretical models, which attempt to understand their period ratio distributions. Then we identify a statistical effect based on an intrinsic asymmetry associated with MMR, and find it play an important role in shaping the period ratio distribution near MMR. Last but least, we also find such an intrinsic asymmetry is existing in asteroids of our solar system.

scholarly journals Sub-Neptune formation: the view from resonant planets

2020 ◽  
Vol 495 (4) ◽  
pp. 4192-4209 ◽  
Author(s):  
Nick Choksi ◽  
Eugene Chiang
Keyword(s):  
Orbital Period ◽  
Core Formation ◽  
Lower Mass ◽  
Period Ratio ◽  
First Order ◽  
Short Scale ◽  
Solar Composition ◽  
Giant Impacts ◽  
Subsequent Modification

ABSTRACT The orbital period ratios of neighbouring sub-Neptunes are distributed asymmetrically near first-order resonances. There are deficits of systems – ‘troughs’ in the period ratio histogram – just short of commensurability, and excesses – ‘peaks’ – just wide of it. We reproduce quantitatively the strongest peak-trough asymmetries, near the 3:2 and 2:1 resonances, using dissipative interactions between planets and their natal discs. Disc eccentricity damping captures bodies into resonance and clears the trough, and when combined with disc-driven convergent migration, draws planets initially wide of commensurability into the peak. The migration implied by the magnitude of the peak is modest; reductions in orbital period are ∼10 per cent, supporting the view that sub-Neptunes complete their formation more-or-less in situ. Once captured into resonance, sub-Neptunes of typical mass $\sim \,$5–15M⊕ stay captured (contrary to an earlier claim), as they are immune to the overstability that afflicts lower mass planets. Driving the limited, short-scale migration is a gas disc depleted in mass relative to a solar-composition disc by three to five orders of magnitude. Such gas-poor but not gas-empty environments are quantitatively consistent with sub-Neptune core formation by giant impacts (and not, e.g. pebble accretion). While disc-planet interactions at the close of the planet formation era adequately explain the 3:2 and 2:1 asymmetries at periods $\gtrsim \, $5–15 d, subsequent modification by stellar tides appears necessary at shorter periods, particularly for the 2:1.

A Synchrotron Radiation Study of Nonlinear Diffusion in Cu-Au

1990 ◽  
Vol 205 ◽  
Author(s):  
E. S. K. Menon ◽  
P. Huang ◽  
M. Kraitchman ◽  
J. J. Hoyt ◽  
P. Chow ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Nonlinear Diffusion ◽  
Pure Copper ◽  
Theoretical Models ◽  
Average Concentration ◽  
Third Order ◽  
Composition Modulation ◽  
First Order ◽  
Diffraction Peaks ◽  
Modulation Wavelength

AbstractAlternate layers of pure copper and gold were vapor deposited on a sodium chloride substrate, the average concentration of the films being Cu-16at% Au and the layering periodicity (modulation wavelength) being 3.31 nm. The composition modulation gives rise to satellite diffraction peaks around the (200) Bragg reflections. Synchrotron radiation at SSRL was able to detect up to third order satellite intensity the evolution of which was measured as a function of annealing time at 515 K. Although the first order satellite intensity decayed as expected exponentially with time, intensities of both second and third order satellites decreased very rapidly at first, then increased before decaying exponentially. These results are in conformity with theoretical models of satellite evolution during annealing in a onedimensional modulated system governed by a nonlinear diffusion equation.

scholarly journals Modeling the Local Bubble

1997 ◽  
Vol 166 ◽  
pp. 121-131 ◽  
Author(s):  
Donald P. Cox
Keyword(s):  
Solar System ◽  
Facial Expressions ◽  
Simplified Model ◽  
Observational Constraints ◽  
Local Bubble ◽  
Interstellar Absorption ◽  
Modeling Effort ◽  
X Ray ◽  
Idealized Modeling ◽  
X Ray Background

AbstractModeling the Local Bubble is one of those activities fraught with danger. It is very easy to be too naive, to fail to consider the dependence of the model on assumptions about the nearby ambient state, or the likelihood of such a structure. It is similarly easy to become so caught up in the details of the vicinity that it is unclear where to begin a necessarily idealized modeling effort. And finally, it is important to remember that the data we have may in some cases be lying to us, and that we have not yet learned to read their facial expressions quite carefully enough.That said, I’ve tried in this paper to be helpful to those who may wish to take the risks. I surveyed the very most basic stories that the data seem to tell, and pointed out the standard coincidences that may be telling us a lot about what is happening, but may turn out once again to have been just coincidences. I’ve described 5 distinct conceptions that in one flavor or another pretty well survey the collection of mental images that have so far been carried by those who’ve attempted models. One may be right, or something entirely different may be more appropriate. It’s at least vital to realize that a conception comes first, followed by a simplified model of details. I’ve also included a long list of questions directed at observers. Some have partial answers, some one wouldn’t know today quite how to approach. But it is a list that students of the soft x-ray background, interstellar absorption lines, possible instrumentation, and the heliosphere may wish to review from time to time, just to see whether they can figure out how to be more helpful. There is another list for modelers, things the models must address, however-so-flimsily if necessary, because there are strong observational constraints (and stronger ones coming) on what can and cannot be present in the local ISM. To that I’ve added a few remarks concerning x-ray emission coming from beyond the Local Bubble, and another few on how x-ray emission from within the solar system might be contaminating what we see. That last bit is new, exciting, and possibly wrong, but it is an example of the ongoing wariness I believe one has to take toward the facts in the case. By the way, Dieter, it really was a great meeting.

scholarly journals Hydrogen molecular ions and the violent birth of the Solar System

2019 ◽  
Vol 377 (2154) ◽  
pp. 20180403 ◽  
Author(s):  
Cecilia Ceccarelli ◽  
Cecile Favre ◽  
Ana López-Sepulcre ◽  
Francesco Fontani
Keyword(s):  
Cosmic Rays ◽  
Solar System ◽  
Past History ◽  
Classical Problem ◽  
Galactic Cosmic Rays ◽  
Energetic Particles ◽  
Molecular Ions ◽  
Observational Constraints ◽  
The Past ◽  
History Of

Many pieces of evidence indicate that the Solar System youth was marked by violent processes: among others, high fluxes of energetic particles (greater than or equal to 10 MeV) are unambiguously recorded in meteoritic material, where an overabundance of the short-lived 10 Be products is measured. Several hypotheses have been proposed to explain from where these energetic particles originate, but there is no consensus yet, mostly because of the scarcity of complementary observational constraints. In general, the reconstruction of the past history of the Solar System is best obtained by simultaneously considering what we know of it and of similar systems nowadays in formation. However, when it comes to studying the presence of energetic particles in young forming stars, we encounter the classical problem of the impossibility of directly detecting them toward the emitting source (analogously to what happens to galactic cosmic rays). Yet, exploiting the fact that energetic particles, such as cosmic rays, create H 3 + and that an enhanced abundance of H 3 + causes dramatic changes on the overall gas chemical composition, we can indirectly estimate the flux of energetic particles. This contribution provides an overview of the search for solar-like protostars permeated by energetic particles and the discovery of a protocluster, OMC-2 FIR4, where the phenomenon is presently occurring. This article is part of a discussion meeting issue ‘Advances in hydrogen molecular ions: H 3 + , H 5 + and beyond’.

scholarly journals The Nasa Solar Probe Mission: In Situ Determination of Interplanetary Out-of-The Ecliptic and Near-Solar Dust Environments

1991 ◽  
Vol 126 ◽  
pp. 29-32
Author(s):  
Bruce T. Tsurutani ◽  
James E. Randolph
Keyword(s):  
Solar Cycle ◽  
Solar System ◽  
Solar Eclipse ◽  
Orbital Period ◽  
High Velocity ◽  
Scientific Community ◽  
The Sun ◽  
Probe Mission

AbstractThe NASA Solar Probe mission will be one of the most exciting dust missions ever flown and will lead to a revolutionary advance in our understanding of dust within our solar system. Solar Probe will map the dust environment from the orbit of Jupiter (5 AU), to within 4 solar radii of the sun’s center. The region between 0.3 AU and 4 Rshas never been visited before, so the 10 days that the spacecraft spends during each (of the two) orbit is purely exploratory in nature. Solar Probe will also reach heliographic latitudes as high as ~ 15 to 28 above (below) the ecliptic on its trajectory inbound (outbound) to (from) the sun. This, in addition to the ESA/NASA Ulysses mission, will help determine the out-of-the-ecliptic dust environment. A post-perihelion burn will reduce the satellite orbital period to 2.5 years about the sun. A possible extended mission would allow data reception for 2 more revolutions, mapping out a complete solar cycle. Because the near-solar dust environment is not well understood (or is controversial at best), and it is very important to have better knowledge of the dust environment to protect Solar Probe from high velocity dust hits, we urgently request the scientific community to obtain further measurements of the near-solar dust properties. One prime opportunity is the July 1991 solar eclipse.

scholarly journals ELECTRON/POSITRON EXCESSES IN THE COSMIC RAY SPECTRUM AND POSSIBLE INTERPRETATIONS

2010 ◽  
Vol 19 (13) ◽  
pp. 2011-2058 ◽  
Author(s):  
YI-ZHONG FAN ◽  
BING ZHANG ◽  
JIN CHANG
Keyword(s):  
Dark Matter ◽  
Supernova Remnant ◽  
Cosmic Ray ◽  
Theoretical Models ◽  
New Physics ◽  
Observational Constraints ◽  
Correct Interpretation ◽  
Observational Feature ◽  
Electron Positron ◽  
Observational Status

The data collected by ATIC, PPB-BETS, FERMI-LAT and HESS all indicate that there is an electron/positron excess in the cosmic ray energy spectrum above ~100 GeV, although different instrumental teams do not agree on the detailed spectral shape. PAMELA also reported clearly the excessive feature of the fraction of positron above several GeV, but with no excess in antiprotons. Here we review the observational status and theoretical models of this interesting observational feature. We pay special attention to various physical interpretations proposed in the literature, including modified supernova remnant models for the e± background, new astrophysical sources, and new physics (the dark matter models). We suggest that although most models can make a case to interpret the data, with the current observational constraints the dark matter interpretations, especially those invoking annihilation, require much more exotic assumptions than some other astrophysical interpretations. Future observations may present some "smoking-gun" observational tests to differentiate different models and to identify the correct interpretation of the phenomenon.

scholarly journals Abell 1763 and its Cluster Feeding Filament: Constraints on the Intra-filament Medium

2010 ◽  
Vol 6 (S277) ◽  
pp. 309-312
Author(s):  
Louise O. V. Edwards ◽  
Dario Fadda
Keyword(s):  
Star Formation ◽  
Radio Source ◽  
Large Scale ◽  
Theoretical Models ◽  
Observational Constraints ◽  
Cosmological Simulations ◽  
Large Scale Structures ◽  
Scale Structures ◽  
Intermediate Density

AbstractGalaxies are found to inhabit a variety of environments. They are often found in pairs, groups, or clusters. Cosmological simulations predict that these clusters are connected on a larger scale by filaments, but because these large scale structures are so vast, and because they are of intermediate density, observational constraints on their properties are difficult to achieve. We find a large-scale filament in the Abell 1763-Abell 1770 superstructure, determine that the star-formation therein is enhanced, and uncover a bent double lobe radio source midway across the filament. From the bend of this AGN'a jets, we probe the density of the surrounding intra-filament medium (IFM), constrained to be between 1-20x10−29 gm/cm3. This density is consistent with direct probes of the IFM as well as theoretical models.

scholarly journals Effective moduli of rocks predicted by the Kuster–Toksöz and Mori–Tanaka models

2021 ◽  
Vol 18 (4) ◽  
pp. 539-557
Author(s):  
Zidong Wang ◽  
Qian Zhang ◽  
Jianlin Liu ◽  
Li-Yun Fu
Keyword(s):  
Volume Fraction ◽  
Theoretical Models ◽  
Effective Modulus ◽  
Petroleum Exploration ◽  
Effective Moduli ◽  
Exploration And Exploitation ◽  
Finite Precision ◽  
First Order ◽  
Scattering Approximation ◽  
Anisotropic Rocks

Abstract Natural rocks are polymineral composites with complex microstructures. Such strong heterogeneities significantly affect the estimation of effective moduli by some theoretical models. First, we have compared the effective moduli of isotropic rocks predicted by the Kuster–Toksöz (KT) model and the Mori–Tanaka (MT) model. The widely used KT model only has finite precision in many cases because of its assumption that is restricted to the first-order scattering approximation. However, the MT model based on the Eshelby tensor in mesomechanics has the advantage of predicting effective moduli of rocks, especially when the volume fraction of embedded inclusions is sufficiently large. In addition, the MT model can be used to predict the effective modulus of anisotropic rocks, but the KT model cannot. For a certain kind of shale or tight sandstones, which are viewed as isotropic composites, both the models work well. For the medium containing spherical pores, both the models produce the same results, whereas for ellipsoidal pores the MT model is more accurate than the KT model, validated by the finite element simulations. In what follows, the applicable ranges of simplified formulas for pores with needle, coin and disk shapes, widely used in engineering, are quantitatively given based on the comparison with the results according to the reduced ellipsoidal formulas of the MT and KT models. These findings provide a comprehensive understanding of the two models in calculating the effective modulus of rocks, which are beneficial to such areas as petroleum exploration and exploitation, civil engineering, and geophysics.

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