We present a mathematical link between Schelling's socio-economic model of segregation and the physics clustering. replace economic concept "utility" by particle's internal energy. As result cluster dynamics is driven "surface tension" force. The resultant segregated areas can be very large behave like spherical "liquid" droplets or as collection static clusters in "frozen" form. This will hopefully provide useful framework for studying many spatial phenomena that involve individuals making...

Our ultimate goal is to probe the nature of collimator outflows in pre-planetary nebula CRL 618. 618 uniquely suited for this purpose owing its multiple, bright, and carefully studied finger-shaped east west nucleus. We compare new Hubble Space Telescope images same filters observed as much 11 yr ago uncover large proper motions surface brightness changes multiple outflows. The expansion age ensemble fingers close 100 yr. find strong variations at fingertips during past decade. Deep IR...

Several hypotheses have been put forward to explain the evolution of extreme sexual size dimorphism (SSD). Among them, gravity hypothesis (GH) explains that SSD has evolved in spiders because smaller males a mating or survival advantage by climbing faster. However, few studies supported this thus far. Using wide span spider body sizes, we show there is an optimal (7.4 mm) for and evolves only that: (1) live high-habitat patches (2) which females are larger than size. We report evidence GH...

Infrared and millimeter-wave emission from Herbig Ae/Be stars has produced conflicting conclusions regarding the dust geometry in these objects. We show that compact dimensions of millimeter-wave-emitting regions are a decisive indication for disks. But disk cannot explain spectral energy distribution unless it is embedded an extended envelope (1) dominates IR (2) provides additional heating on top direct stellar radiation. Detailed radiative transfer calculations based simplest model...

We examine the ``puffed-up inner disk'' model (Dullemond, Dominik & Natta 2001), proposed for explaining near-IR excess radiation from Herbig Ae/Be stars. Detailed computations show that observed requires more hot dust than is contained in puffed-up disk rim. The rim can produce only if its has perfectly gray opacity, but such conflict with 10$μ$m spectral feature. find a compact ($\sim$ 10 AU) tenuous ($τ_V \la 0.4$) dusty halo around regions contains enough to readily explain...

We present a new model-independent method of comparison NIR visibility data YSOs. The is based on scaling the measured baseline with YSO's distance and luminosity, which removes dependence these two variables. use this to compare all available demonstrate that it distinguishes YSOs luminosity L⋆ ≲ 103 L☉ (low L) from ≳ (high L). This confirms earlier suggestions, fits image models data, for difference between sizes groups. When plotted against "scaled" baseline, creates following clusters:...

We study the infrared (IR) emission from flared discs with and without additional optically thin haloes. Flux calculations of a disc in vacuum can be considered special case more general family models which is imbedded an halo. In absence such halo, flux measurements never rule out its existence because flaring surface defines mathematically equivalent halo that produces exact same at all IR wavelengths. When height H outer radius R whose optical depth visual wavelengths τhalo, system...

BackgroundAnimals have been hypothesized to benefit from pendulum mechanics during suspensory locomotion, in which the potential energy of gravity is converted into kinetic according energy-conservation principle. However, no convincing evidence has found so far. Demonstrating that morphological evolution follows important a biomechanical point view because locomotion some traits could be decoupled gravity, thus allowing independent adaptive these two when compared animals move standing on...

We present four-color images of CRL 2688 obtained in 2009 using the Wide-Field Camera 3 on HST. The F606W image is compared with archival very similar filters to monitor proper motions nebular structure. find that bright N-S lobes have expanded uniformly by 2.5% and ensemble rings has translated radially 0.07 6.65 y. were ejected every 100y for ~4 millennia until formed 250y ago. Starlight scattered from edges dark E-W dust lane coincident extant H2 leading tips eight pairs CO outflows....

The luminosity of the central source in ionizing radiation is an essential parameter a photoionized environment, and one most fundamental physical quantities can measure. We outline method determining for any emission-line region using only infrared data. In dusty environments, grains compete with hydrogen absorbing continuum radiation. Grains produce emission, produces recombination lines. have computed very large variety photoionization models, ranges abundances, grain mixtures, continua,...

Near-infrared imaging of the asymptotic giant branch (AGB) star IRC+10011 (= CIT3) reveals presence a bipolar structure within central ∼0.1 arcsec spherical dusty wind. We show that image asymmetries originate from ∼10−4 M⊙ swept-up wind material in an elongated cocoon whose expansion is driven by jets. perform detailed 2D radiative transfer calculations with modelled as two cones extending to ∼1100 au opening angle ∼30°, embedded standard r−2 density profile. The started ≲200 yr ago, while...

Electrophonic meteor sounds, heard simultaneously with the appearance, are a longstanding problem due to their nonintuitive nature. Previous investigations have been undermined by lack of instrumental recordings. Here we present first detection electrophonic sounds obtained during observation 1998 Leonids from Mongolia. Two Leonid fireballs brightness −6.5 m and −12 produced short, low‐frequency which were recorded microphones in special setup different observers. Simultaneous measurements...

ABSTRACT We explore the dynamical behaviour of dust particles that populate surface inner optically thick protoplanetary discs. This is a disc region with hottest and great importance for planet formation evolution, but we still struggle to understand all forces shape this environment. In our approach, combine results from two separate numerical studies, one wind velocity density distributions obtained magnetohydrodynamical simulations accretion discs, other high-resolution multigrain...

Computer vision algorithms are powerful tools in astronomical image analyses, especially when automation of object detection and extraction is required. Modern astronomy oriented towards stars galaxies, ignoring completely the existing linear features. With emergence wide-field sky surveys, features attract scientific interest as possible trails fast flybys near-Earth asteroids meteors. In this work, we describe a new feature algorithm designed specifically for implementation big data...

Given the current limited knowledge of meteor plasma micro-physics and its interaction with surrounding atmosphere ionosphere, meteors are a highly interesting observational target for high-resolution wide-field astronomical surveys. Such surveys capable resolving physical size heads, but they produce large volumes images that need to be automatically inspected possible existence long linear features produced by meteors. Here we show how big aperture sky survey telescopes detect as defocused...

The structure of inner region protoplanetary disks around young pre-main-sequence stars is still poorly understood. This part the disk shaped by various forces that influence dust and gas dynamics, sublimation, which creates abrupt drops in density. also emits strong near-infrared excess cannot be explained classical accretion models, suggests existence some unusual distribution or shape. most prevalent explanation to date puffed-up rim model, where exhibits an optically thin cavity star up...

We explore dust flow in the hottest parts of protoplanetary discs using forces gravity, gas drag and radiation pressure. Our main focus is on optically thin regions dusty disc, where exposed to most extreme heating conditions dynamical perturbations: surface thick disc inner sublimation zone. utilise results from two numerically strenuous fields research. The first quasi-stationary solutions velocity density distributions mangetohydrodynamical (MHD) simulations accretion discs. This critical...

It was recently discovered that the temperature in surface layer of externally heated optically thick gray dust clouds increases with optical depth for some distance from surface, as opposed to normal decrease rest cloud. This inversion is a result efficient absorption diffuse flux cloud interior by exposed external radiation. Grains size 1 μm or bigger experience this effect when stellar spectrum. We explore what happens mixture grain sizes (multigrain). Two possible boundary conditions are...

Our current understanding of the physical conditions in inner regions protoplanetary discs is becoming increasingly challenged by more detailed observational and theoretical explorations. Calculation dust temperature one key features we strive to understand a necessary step image flux reconstruction. We explore coexistence small (0.1mic radius) big (2mic grains can coexist at distances from star where would not survive without shielding them direct starlight. The study required high...

Meteor science contributes greatly to the study of Solar System and Earth's atmosphere. However, despite its importance very long history, meteor still has a lot explore in domain plasma microphysics meteor-ionosphere interaction. Meteors are actually difficult target for high‐resolution observations, which leads need more ambitious interdisciplinary observational setups campaigns. We describe some recent developments physics flight argue that should be fully integrated into cases large...