Making Habitable Worlds: Planets Versus Megastructures

In 2016, a star KIC 8462852 caught the world's attention due to a paper by citizen scientists who noticed its seemingly unexplainable brightness variations. The forward theory was offered - KIC 8462852 is surrounded by a Dyson sphere, a megastructure made by an alien civilization to collect all energy output from their star. Finally, in 2018, its light curve showed chromaticity more characteristic of the dust (from comets or asteroids) rather than of something made from solid material, but the world was woken up to the idea of megastructures. But, in Dyson's time, only Solar System planets were known; it took more than 20 years to realize that nature has no problem making planets and does it with a flair -- the total number of planets in the Galaxy is estimated to be in billions. With such abundance of planets, there would be no need to destroy the entire planetary system to make one sphere. Instead, a civilization can expand to a system that has planet(s) in the habitable zone (HZ), or a planet can be moved into it. Alternatively, a free-floating planet (FFP) can be captured and moved into the HZ. These shifts can be performed at a constant low-thrust acceleration using high power directional lasers, resulting in a gradual spiral transfer from one orbit to another. We propose here to search for ETI by looking for high-power laser technosignatures and consider merits of such signatures. We suggest to specifically pay attention to the multiple planetary systems that have Strange Exoplanetary Architectures (SEA) - unusual planetary arrangements that cannot be explained by current planetary formation theories, because these could be the result of ETI moving planets intentionally to suit their needs.Comment: 11 page, 7 figure

Motion of a Vector Particle in a Curved Spacetime. I. Lagrangian Approach

From the simple Lagrangian the equations of motion for the particle with spin are derived. The spin is shown to be conserved on the particle world-line. In the absence of a spin the equation coincides with that of a geodesic. The equations of motion are valid for massless particles as well, since mass does not enter the equations explicitely.Comment: 6 pages, uses mpla1.sty, published in MPLA, replaced with corrected typo

Image Improvement and Restoration in Optical Time Series. I. The Method

Globular clusters (GCs) are considered strong candidates for hosting rogue (free-floating) planets. Since they are not bound to a star, they are undetectable by any traditional detection methods: transit, radial velocity, or direct imaging. Gravitational microlensing (ML), which causes transient brightening of background stars by passing foreground masses, is, on the other hand, an established method of detecting planets and proves promising for application in GCs. By employing the image subtraction technique, differential photometry on the time-series images of GCs could extract variability events, build light curves and inspect them for the presence of microlensing. However, instrumental anomalies and varying observing conditions over a long observational campaign period result in the distortion of stellar Point Spread Function (PSF), which affects the subtraction quality and leads to false-positive transient detection and large-scale noise structure in the subtracted images. We propose an iterative image reconstruction method as a modification to the Scaled Gradient Projection (SGP) algorithm, called the Flux-Conserving Scaled Gradient Projection (FC-SGP), to restore the shapes of stars while preserving their flux well within the photometrically accepted tolerance. We perform an extensive empirical comparative study of FC-SGP with different image restoration algorithms like the Richardson-Lucy (RL) and the original SGP algorithms, using several physically motivated metrics and experimental convergence analysis. We find that FC-SGP could be a promising approach for astronomical image restoration. In the future, we aim to extend its application to different image formats while maintaining the performance of the proposed algorithm.Comment: Submitted to MNRA

Degeneracy in exotic gravitational lensing

We present three different theoretically foreseen, but unusual, astrophysical situations where the gravitational lens equation ends up being the same, thus producing a degeneracy problem. These situations are (a) the case of gravitational lensing by exotic stresses (matter violating the weak energy condition and thus having a negative mass, particular cases of wormholes solutions can be used as an example), (b) scalar field gravitational lensing (i.e. when considering the appearance of a scalar charge in the lensing scenario), and (c) gravitational lensing in closed universes (with antipodes).The reasons that lead to this degeneracy in the lens equations, the possibility of actually encountering it in the real universe, and eventually the ways to break it, are discussed.Comment: Accepted for publication in Modern Physics Letters

Planning of the Internal Audit of Supply Chain Management in Foreign Economic Activity: Theory and Practice (Internal Audit Planning)

Abstract- Foreign economic activity and export operations in particular have a number of peculiarities, which significantly complicate the procedure for the accounting and distinguish them from the other business operations based on the supply chain. The existing legislative base for accounting and taxation does not provide unique regulations on the specifics of foreign trade contracts, pushing this responsibility down on economic entities. As a result, business processes of foreign economic activity may be reflected incorrectly in the accounting and analytical system. These reasons contribute to the complication of the procedures of audit evidence collection, the process of planning and documenting of the internal audit of foreign economic activity. The purpose of the study is to develop a methodology for internal audit planning and a concept of its strategy for export operations. As a result, the quality and reliability of the accounting [financial) statements should be improved. The results of monographic and regulatory analysis allowed us to determine the aspects of accounting that are at risk of data contamination. Using the methods of expert evaluation, information synthesis and supply chain strategy, the most optimal focus areas of audit program planning were determined. The present research introduces the author’s algorithm for internal audit planning, as well as the set of working documents to be implemented at this stage, i.e., internal control tests and audit plan. The audit plan, developed by the authors, includes the main directions of the internal audit of the export operations and contributes to a complex evaluation of the accounting accuracy. In addition, it optimizes significantly the verification process in terms of the labor costs and time expenditure. The author’s recommendations on planning and documenting can be applied for further development of theoretical and practical issues of the internal audit of foreign economic activity