scholarly journals Mass distributions of meteorites

2020 ◽  
Vol 493 (3) ◽  
pp. 4058-4064
Author(s):  
Alberto S Betzler ◽  
Ernesto P Borges
Keyword(s):  
Statistical Mechanics ◽  
Observational Data ◽  
Mass Distribution ◽  
Exponential Function ◽  
Fragmentation Process ◽  
Statistical Distributions ◽  
Mass Distributions ◽  
Gibbs Entropy ◽  
Collection Sites

ABSTRACT For at least five decades, the study of the mass distribution of meteorites has been carried out. This study aims to obtain the flux of material that comes to the Earth’s surface. For this, the observational data were modelled statistical distributions of the most varied types, derived from Gibbs entropy. However, it appears that the fragmentation process is probably complex in nature. Given this particularity, we model the mass distribution of meteorites using the q-exponential function, derived from Tsallis non-extensive statistical mechanics. This distribution is capable of modelling the entire observed spectrum of meteorite mass regardless of whether the specimens originate from the fragmentation of a single meteorite, belong to the same mineralogical group or type, or when are separated by collection sites on the Earth’s surface. We suggest that most meteorite samples are incomplete in certain mass ranges due to the action of the so-called gathering bias.

QELSS diffusion data for moderately broad molar mass distribution polymer samples compared with data from classical gradient techniques

1989 ◽  
Vol 54 (7) ◽  
pp. 1821-1829
Author(s):  
Bedřich Porsch ◽  
Simon King ◽  
Lars-Olof Sundelöf
Keyword(s):  
Diffusion Coefficient ◽  
Mass Distribution ◽  
Molar Mass ◽  
Molar Mass Distribution ◽  
Diffusion Data ◽  
Mass Distributions ◽  
Classical Diffusion ◽  
Polydisperse Polymer

The differences between the QELSS and classical diffusion coefficient of a polydisperse polymer resulting from distinct definitions of experimentally accessible average values are calculated for two assumed specific forms of molar mass distributions. Predicted deviations are compared with the experiment using NBS 706 standard polystyrene. QELSS Dz of this sample relates within 2-4% to the classical diffusion coefficient, if the Schulz-Zimm molar mass distribution is assumed to be valid. In general, differences between the height-area and QELSS diffusion coefficient of about 20% may be found for Mw/Mn ~ 2, and this value may increase above 35%, if strongly tailing molar mass distribution pertains to the sample.

scholarly journals Neutron star masses

2012 ◽  
Vol 8 (S291) ◽  
pp. 146-146
Author(s):  
David Nice
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Nuclear Matter ◽  
Observational Data ◽  
Mass Distribution ◽  
Binary Star ◽  
Star Mass ◽  
Star Evolution ◽  
Neutron Star Mass ◽  
Present Understanding

AbstractNeutron star masses can be inferred from observations of binary pulsar systems, particularly by the measurement of relativistic phenomena within these orbits. The observed distribution of masses can be used to infer or constrain the equation of state for nuclear matter and to study astrophysical processes such as supernovae and binary star evolution. In this talk, I will review our present understanding of the neutron star mass distribution with an emphasis on the observational data.

scholarly journals N-Body Results on Dark Matter

1987 ◽  
Vol 117 ◽  
pp. 263-278
Author(s):  
Simon D. M. White
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Cold Dark Matter ◽  
Density Fluctuations ◽  
Major Difficulty ◽  
Mass Distributions ◽  
Galaxy Distribution ◽  
Galaxy Halos ◽  
Flat Rotation Curves ◽  
The Universe

The structure of the dominant “dark” component of the Universe may evolve primarily under the influence of gravity. A number of models for the evolution of the Universe make specific predictions for the statistical properties of density fluctuations at early times. N-body simulations can follow the nonlinear development of such fluctuations to the present day. A major difficulty arises because we cannot observe the present mass distribution directly. Recent N-body work has concentrated on models dominated by weakly interacting free elementary particles. Neutrino-dominated but otherwise conventional cosmologies pass rapidly from a smooth distribution to one dominated by lumps with masses greater than those of any known object. Cosmologies dominated by “cold dark matter” produce mass distributions which fit the observed galaxy distribution (i) if Ω = 0.1–0.2 and galaxies follow the mass distribution, or (ii) if Ω = 1, HO< 50 km/s/Mpc and galaxies form preferentially in high density regions. In the latter case, clumps form with flat rotation curves with about the amplitude and abundance expected for galaxy halos.

scholarly journals Differences in Mass Distribution for Field and Cluster Spiral Galaxies

1987 ◽  
Vol 117 ◽  
pp. 66-66 ◽  
Author(s):  
David Burstein ◽  
Vera C. Rubin
Keyword(s):  
Mass Distribution ◽  
Classification Scheme ◽  
Spiral Galaxies ◽  
Three Dimensional ◽  
Rotation Curves ◽  
Mass Distributions ◽  
Distribution Form ◽  
Simple Classification ◽  
Observational Fact

Our group has now obtained rotation curves for 80 spiral galaxies, Hubble types Sa through Sd. As described in Rubin et al. (Ap. J. 289, 81; 1985), the forms of these rotation curves are similar for all Hubble types. Given this observational fact, we have chosen to analyze the mass distributions for these galaxies under the assumption that the mass distributions for all spirals can be described by the same three-dimensional form, here taken to be spherical for simplicity. The mass distribution forms for 71 of these galaxies can be placed into a simple classification scheme based on the curvature of mass distribution form in a log(radius) - log (integral mass) diagram. The three most common mass forms among this continuum are termed Types I, II and III, the forms of which are displayed below (see also the discussion by Rubin elsewhere in this Symposium).

ON THE EXTENSIVITY OF THE ENTROPY Sq FOR N ≤ 3 SPECIALLY CORRELATED BINARY SUBSYSTEMS

2006 ◽  
Vol 16 (06) ◽  
pp. 1727-1738 ◽  
Author(s):  
YUZURU SATO ◽  
CONSTANTINO TSALLIS
Keyword(s):  
Statistical Mechanics ◽  
Stationary States ◽  
Nonextensive Statistical Mechanics ◽  
Entropy Formula ◽  
Gibbs Entropy ◽  
Statistical Mechanical

Many natural and artificial systems whose range of interaction is long enough are known to exhibit (quasi)stationary states that defy the standard, Boltzmann–Gibbs statistical mechanical prescriptions. For handling such anomalous systems (or at least some classes of them), nonextensive statistical mechanics has been proposed based on the entropy [Formula: see text], with [Formula: see text] (Boltzmann–Gibbs entropy). Special collective correlations can be mathematically constructed such that the strictly additive entropy is now Sq for an adequate value of q ≠ 1, whereas Boltzmann–Gibbs entropy is nonadditive. Since important classes of systems exist for which the strict additivity of Boltzmann–Gibbs entropy is replaced by asymptotic additivity (i.e. extensivity), a variety of classes are expected to exist for which the strict additivity of Sq (q ≠ 1) is similarly replaced by asymptotic additivity (i.e. extensivity). All probabilistically well defined systems whose adequate entropy is S1 are called extensive (or normal). They correspond to a number W eff of effectively occupied states which grows exponentially with the number N of elements (or subsystems). Those whose adequate entropy is Sq (q ≠ 1) are currently called nonextensive (or anomalous). They correspond to W eff growing like a power of N. To illustrate this scenario, recently addressed [Tsallis, 2004] we provide in this paper details about systems composed by N = 2, 3 two-state subsystems.

scholarly journals Bivariate luminosity-HI mass distribution function of galaxies based on the NIBLES survey

2018 ◽  
Vol 619 ◽  
pp. A89 ◽  
Author(s):  
Z. Butcher ◽  
S. Schneider ◽  
W. van Driel ◽  
M. D. Lehnert
Keyword(s):  
Mass Distribution ◽  
Luminosity Function ◽  
Hubble Constant ◽  
Mass Function ◽  
Volume Density ◽  
Local Universe ◽  
Mass Distributions ◽  
Low Mass ◽  
The Mean ◽  
Mass Distribution Function

We present a new optical luminosity-HI mass bivariate luminosity function (BLF) based on HI line observations from the Nançay Interstellar Baryons Legacy Extragalactic Survey (NIBLES). NIBLES sources lie within the local universe (900 ≤ c z ≤ 12 000 km s−1) and were chosen from SDSS DR5 such that the optical luminosity function was sampled as uniformly as possible. The HI mass function (HIMF) derived from our raw-data BLF, which is based on HI detections only, is consistent with the HIMFs derived from other optically selected surveys in that the low-mass slope is flatter than those derived from blind HI surveys. However, spanning the entire luminosity range of NIBLES, we identify a highly consistent distribution of the HI gas mass to luminosity ratio (gas-to-light ratio) with a predictable progression in the mean MHI/L r ratio as a function of L r. This consistency allows us to construct plausible gas-to-light ratio distributions for very low-luminosity bins which lie outside the NIBLES sample. We also identify a ∼10% decrease in detection fraction for galaxies fainter than log(L r) = 9.25, consistent with the expected decrease due to distance and sensitivity effects. Accounting for these trends, we reconstruct plausible gas-to-light distributions spanning luminosity bins down to log(L r) = 5.25, thus producing a corrected BLF. This corrected BLF is in good qualitative agreement with optical luminosity-HI mass distributions from the ALFALFA survey and is able to accurately reproduce blind survey HIMFs, lending credibility that this two dimensional optical luminosity-HI mass distribution is an accurate representation of the volume density distribution of galaxies in the local universe. We also note that our agreement with HIMFs from other surveys is dependent on accounting for all systematic differences such as selection method, Hubble constant and HI flux scale.

scholarly journals The influence of 5-iron clubhead mass distribution on clubhead presentation and initial ball launch conditions: Part I: Golf robot tests

2020 ◽  
pp. 175433712096935
Author(s):  
ES Wallace ◽  
TW Corke ◽  
KM Jones ◽  
NF Betzler ◽  
SR Otto
Keyword(s):  
Linear Regression ◽  
Mass Distribution ◽  
Scientific Study ◽  
Mass Distributions ◽  
Centre Of Gravity ◽  
Perceived Performance ◽  
Robot Group

It is well accepted that iron clubhead properties affect shot outcomes in golf. However, the mechanisms that contribute to this relationship have not received recent scientific study. The purpose of this study was to determine how the different clubhead mass distributions in a blade 5-iron and a cavity-back 5-iron affect clubhead presentation and ball launch conditions. Nine clubhead presentation variables and four ball launch variables were measured for ten discrete impact locations and five face angles during swings using a golf robot. Group means were analysed statistically using an independent samples approach to identify differences and linear regression was used to indicate relationships between key launch variables. The cavity-back showed higher effective clubhead loft with greater total ball spin than the blade, despite having matched static lofts, whilst also providing more consistent launch outcomes across a range of impact locations. Evidence of the phenomenon known as the ‘gear effect’ was found for the cavity-back, but not the blade, suggesting that the threshold at which the clubhead’s centre of gravity (CG) is deep enough to detect the gear effect lies between the CGs of the two 5-iron types. These novel robot test findings lend support to the perceived performance benefits of perimeter-weighted irons; whether these effects translate to human golfer swings is reported in Part II of this paper.

scholarly journals Mass distribution of magnetized quark-nugget dark matter and comparison with requirements and observations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
J. Pace VanDevender ◽  
Ian M. Shoemaker ◽  
T. Sloan ◽  
Aaron P. VanDevender ◽  
Benjamin A. Ulmen
Keyword(s):  
Magnetic Field ◽  
Dark Matter ◽  
Mass Distribution ◽  
Ferromagnetic State ◽  
Gluon Plasma ◽  
Peat Bogs ◽  
Mass Distributions ◽  
Normal Matter ◽  
Expansion Of The Universe ◽  
Quark Nuggets

Abstract Quark nuggets are a candidate for dark matter consistent with the Standard Model. Previous models of quark nuggets have investigated properties arising from their being composed of strange, up, and down quarks and have not included any effects caused by their self-magnetic field. However, Tatsumi found that the core of a magnetar star may be a quark nugget in a ferromagnetic state with core magnetic field Bsurface = 1012±1 T. We apply Tatsumi’s result to quark-nugget dark-matter and report results on aggregation of magnetized quark nuggets (MQNs) after formation from the quark-gluon plasma until expansion of the universe freezes out the mass distribution to ~ 10−24 kg to ~ 1014 kg. Aggregation overcomes weak-interaction decay. Computed mass distributions show MQNs are consistent with requirements for dark matter and indicate that geologic detectors (craters in peat bogs) and space-based detectors (satellites measuring radio-frequency emissions after passage through normal matter) should be able to detect MQN dark matter. Null and positive observations narrow the range of a key parameter Bo ~ Bsurface to 1 × 1011 T < Bo ≤ 3 × 1012 T.

scholarly journals Synthetic P-AGB Evolution

1993 ◽  
Vol 155 ◽  
pp. 473-476 ◽  
Author(s):  
Letizia Stanghellini ◽  
Alvio Renzini
Keyword(s):  
Mass Distribution ◽  
Planetary Nebula ◽  
Asymptotic Giant Branch ◽  
Transition Time ◽  
Mass Relation ◽  
Agb Stars ◽  
Mass Distributions ◽  
Luminosity Functions ◽  
Observational Errors ◽  
Pn Stage

Extensive Montecarlo simulations of Post-Asymptotic Giant Branch (P-AGB) populations have been constructed, exploring the effects of various assumptions on synthetic H-R diagrams, luminosity functions, and inferred mass distributions. Such assumptions include the IMF, the initial mass-final mass relation, the AGB to PN transition time, the duration of the planetary nebula (PN) stage, etc. We have also investigated how the observational errors in luminosity and temperature propagate into the inferred mass distribution of the P-AGB stars.

The influx of comets and asteroids to the Earth

1981 ◽  
Vol 303 (1477) ◽  
pp. 353-368 ◽  
Keyword(s):  
Size Distribution ◽  
Mass Distribution ◽  
Diameter Distribution ◽  
Sources Of Information ◽  
Mass Distributions ◽  
The Earth

Knowledge of the size distribution of comets and asteroids can be obtained from two sources. First the planet Earth can be regarded as a detector and the diameter distribution of Earth craters used to assess the mass distribution of the incident bodies. Secondly observations from Earth of the characteristics and orbits of comets and asteroids can lead to their collision probabilities and mass distributions. Simplistically it can be stated that the Earth craters have been produced by small incident objects whereas the comets and asteroids that are easily seen are the large ones. This paper seeks to relate these diverse sources of information.

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