ISPY – NaCo Imaging Survey for Planets around Young stars

Context. The interaction between low-mass companions and the debris discs they reside in is still not fully understood. A debris disc can evolve due to self-stirring, a process in which planetesimals can excite their neighbours to the point of destructive collisions. In addition, the presence of a companion could further stir the disc (companion-stirring). Additional information is necessary to understand this fundamental step in the formation and evolution of a planetary system, and at the moment of writing only a handful of systems are known where a companion and a debris disc have both been detected and studied at the same time. Aims. Our primary goal is to augment the sample of these systems and to understand the relative importance between self-stirring and companion-stirring. Methods. In the course of the VLT/NaCo Imaging Survey for Planets around Young stars (ISPY), we observed HD 193571, an A0 debris disc hosting star at a distance of 68 pc with an age between ∼60 and 170 Myr. We obtained two sets of observations in L′ band and a third epoch in H band using the GPI instrument at Gemini-South. Results. A companion was detected in all three epochs at a projected separation of ∼11 au (∼0.17″), and co-motion was confirmed through proper motion analysis. Given the inferred disc size of 120 au, the companion appears to reside within the gap between the host star and the disc. Comparison between the L′ and H band magnitude and evolutionary tracks suggests a mass of ∼0.31 − 0.39 M⊙. Conclusions. We discovered a previously unknown M-dwarf companion around HD 193571, making it the third low-mass stellar object discovered within a debris disc. A comparison to self- and companion-stirring models suggests that the companion is likely responsible for the stirring of the disc.

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The UV/X-ray radiation fields and particle (CME) flows of M dwarf exoplanet host stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320000162 ◽

2019 ◽

Vol 15 (S354) ◽

pp. 377-383

Author(s):

Alexander Brown

Keyword(s):

Hubble Space Telescope ◽

High Energy ◽

Atmospheric Conditions ◽

X Ray ◽

Radiation Fields ◽

Uv Emission ◽

Low Mass ◽

Formation And Evolution ◽

M Dwarf ◽

Host Stars

AbstractThe high energy X-ray and UV radiation fields of host stars play a crucial role in determining the atmospheric conditions and habitability of potentially-habitable exoplanets. This paper focuses on the major surveys of the UV/X-ray emissions of M- and K-type exoplanet hosts that have been undertaken by the MUSCLES and MegaMUSCLES Hubble Space Telescope (HST) Treasury programs and associated contemporaneous X-ray and ground-based observations. The quiescent and flaring radiation (both photons and implied particles) were observed from this extensive sample of relatively old, low mass, exoplanet host stars and show that, from the viewpoint of a habitable-zone exoplanet, there is no such thing as an “inactive” M dwarf star. The resulting implications are significant for planetary habitability. Extensive monitoring of the X-ray/UV emission from a representative younger M dwarf is also presented and the direct stellar effects that influence exoplanets during the earlier phases of their formation and evolution discussed.

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The Observational Evidence for Accretion

Symposium - International Astronomical Union ◽

10.1017/s0074180900061805 ◽

1997 ◽

Vol 182 ◽

pp. 391-405 ◽

Cited By ~ 2

Author(s):

Lee Hartmann

Keyword(s):

Large Range ◽

Observational Evidence ◽

Young Stars ◽

Young Stellar Objects ◽

Stellar Objects ◽

T Tauri ◽

Accretion Rates ◽

Low Mass ◽

Stellar Magnetospheres ◽

Mass Ejection

Outflows from low-mass young stellar objects are thought to draw upon the energy released by accretion onto T Tauri stars. I briefly summarize the evidence for this accretion and outline present estimates of mass accretion rates. Young stars show a very large range of accretion rates, and this has important implications for both mass ejection and for the structure of stellar magnetospheres which may truncate T Tauri disks.

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Results of Archaeoparasitological and Palynological Analyzes of the Contents of the Sewage Drain of the Chorgun Tower (South-Western Crimea)

Stratum plus. Archaeology and Cultural Anthropology ◽

10.55086/sp216377389 ◽

2021 ◽

pp. 377-389

Author(s):

Evgeniy Nedelkin ◽

◽

Alexander Khrustalev ◽

Anna Babenko ◽

Sergey Slepchenko ◽

...

Keyword(s):

Intestinal Parasites ◽

Gastrointestinal Diseases ◽

Archaeological Research ◽

Additional Information ◽

The Third ◽

15Th Century ◽

Palynological Study ◽

Sanitary Conditions ◽

The Village ◽

Constant Source

The article presents the results of an archaeoparasitological and palynological study of a sample taken from the sewage drain of the Chorgun Tower. This is a fortification on the territory of the village of Chernorechie (South-Western Crimea). According to archaeological research, the construction of the keep dates back to the third quarter of the 15th century. Four types of eggs of intestinal parasites infecting humans and synanthropic animals were identified in the sample. Regarding parasitic and infectious gastrointestinal diseases, human whipworm and roundworm eggs found in the sample are indicative of relatively unfavorable sanitary conditions of the fortification. Based on the features of the archaeoparasitological spectrum, it can be concluded that anthelminthic agents were used or food with antiparasitic effects against roundworms was consumed. The difficult sanitary and epidemiological situation was also complicated by synanthropic rodents, such as rats and domestic mice, which could be a constant source of dangerous infections in the Chorgun Keep. A palynological study of the contents of the sewage runoff made it possible to obtain additional information on the nutrition of people who used the latrine facilities in the Chorgun Keep. What is equally important is that the study demonstrates the possibilities of methods for the study of canalization as a source of bioarchaeological information.

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Red Optical Planet Survey: A radial velocity search for low mass M dwarf planets

EPJ Web of Conferences ◽

10.1051/epjconf/20134705002 ◽

2013 ◽

Vol 47 ◽

pp. 05002

Author(s):

J.R. Barnes ◽

J.S. Jenkins ◽

H.R.A. Jones ◽

P. Rojo ◽

P. Arriagada ◽

...

Keyword(s):

Radial Velocity ◽

Dwarf Planets ◽

Low Mass ◽

M Dwarf

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Full exploration of the giant planet population around β Pictoris

Astronomy and Astrophysics ◽

10.1051/0004-6361/201730436 ◽

2018 ◽

Vol 612 ◽

pp. A108 ◽

Cited By ~ 11

Author(s):

A.-M. Lagrange ◽

M. Keppler ◽

N. Meunier ◽

J. Lannier ◽

H. Beust ◽

...

Keyword(s):

Extrasolar Planets ◽

Giant Planet ◽

Young Stars ◽

Giant Planets ◽

Close Orbit ◽

Wide Range ◽

Detection Probabilities ◽

Solar Type ◽

Formation And Evolution ◽

The One

Context. The search for extrasolar planets has been limited so far to close orbit (typ. ≤5 au) planets around mature solar-type stars on the one hand, and to planets on wide orbits (≥10 au) around young stars on the other hand. To get a better view of the full giant planet population, we have started a survey to search for giant planets around a sample of carefully selected young stars. Aims. This paper aims at exploring the giant planet population around one of our targets, β Pictoris, over a wide range of separations. With a disk and a planet already known, the β Pictoris system is indeed a very precious system for studies of planetary formation and evolution, as well as of planet–disk interactions. Methods. We analyse more than 2000 HARPS high-resolution spectra taken over 13 years as well as NaCo images recorded between 2003 and 2016. We combine these data to compute the detection probabilities of planets throughout the disk, from a fraction of au to a few dozen au. Results. We exclude the presence of planets more massive than 3 MJup closer than 1 au and further than 10 au, with a 90% probability. 15+ MJup companions are excluded throughout the disk except between 3 and 5 au with a 90% probability. In this region, we exclude companions with masses larger than 18 (resp. 30) MJup with probabilities of 60 (resp. 90) %.

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The formation and evolution of a diffusive interface

Journal of Fluid Mechanics ◽

10.1017/s0022112096003862 ◽

1997 ◽

Vol 331 ◽

pp. 199-229 ◽

Cited By ~ 13

Author(s):

M. JEROEN MOLEMAKER ◽

HENK A. DIJKSTRA

Keyword(s):

Numerical Simulation ◽

Mixed Layer ◽

Numerical Results ◽

Necessary Condition ◽

Mixing Efficiency ◽

Final Thickness ◽

Formation And Evolution ◽

Diffusive Interface ◽

The Moment ◽

Energy Balances

The formation and evolution of a diffusive interface in a stable salt-stratified layer cooled from above is studied in a two-dimensional geometry by direct numerical simulation. For a typical example with realistic parameters, the evolution of the flow is computed up to the moment where three layers can be distinguished. Focus is on the development of the first mixed layer. The convective velocity scaling as proposed by Hunt (1984) and previously proposed expressions for the interfacial heat flux (Huppert 1971; Fernando 1989a) are shown to correspond well with the results of the simulation. The evolution of the first layer can be well described by an entrainment relation based on a local balance between kinetic and potential energy with mixing efficiency γ. The new entrainment relation is shown to fit the numerical results well and an interpretation of γ in terms of the overall energy balances of the flow is given.Previously, two rival mechanisms have been proposed that determine the final thickness of the first layer (Turner 1968; Fernando 1987). One of the distinguishing features of both mechanisms is whether a transition in entrainment regime – as the first layer develops – is a necessary condition for the mixed layer to stop growing. Another is the presence of a buoyancy jump over the interface before substantial convection in the second layer occurs. From the numerical results, we find a significant buoyancy jump even before the thermal boundary layer ahead of the first layer becomes unstable. Moreover, the convective activity in the second layer is too small to be able to stop the growth of the first layer. We therefore favour the view proposed by Fernando (1987) that a transition in entrainment regime determines the thickness of the first layer. Following this, a new one-dimensional model of layer formation is proposed. Important expressions within this model are verified using the results of the numerical simulation. The model contains two constants which are determined from the numerical results. The results of the new model fit experimental results quite well and the parameter dependence of the thickness of the first layer is not sensitive to the values of the two constants.

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A kinematically hot population of young stars in the solar neighbourhood

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa909 ◽

2020 ◽

Vol 494 (2) ◽

pp. 2429-2439 ◽

Cited By ~ 1

Author(s):

A S Binks ◽

R D Jeffries ◽

N J Wright

Keyword(s):

Young Stars ◽

Solar Neighbourhood ◽

Mass Distributions ◽

Systematic Effort ◽

Low Mass ◽

Moving Groups

ABSTRACT In the last three decades several hundred nearby members of young stellar moving groups (MGs) have been identified, but there has been less systematic effort to quantify or characterize young stars that do not belong to previously identified MGs. Using a kinematically unbiased sample of 225 lithium-rich stars within 100 pc, we find that only 50 ± 10 per cent of young (≲125 Myr), low-mass (0.5 < M/M⊙ < 1.0) stars, are kinematically associated with known MGs. Whilst we find some evidence that five of the non-MG stars may be connected with the Lower Centaurus–Crux association, the rest form a kinematically ‘hotter’ population, much more broadly dispersed in velocity, and with no obvious concentrations in space. The mass distributions of the MG members and non-MG stars are similar, but the non-MG stars may be older on average. We briefly discuss several explanations for the origin of the non-MG population.

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CONSTRUCTION OF AN EFFECTIVE WAREHOUSE SYSTEM OF THE ENTERPRISE IN THE PROCESSING OF AGRICULTURAL CARGO

Municipal economy of cities ◽

10.33042/2522-1809-2021-6-166-217-226 ◽

2021 ◽

Vol 6 (166) ◽

pp. 217-226

Author(s):

O. Pavlenko ◽

D. Velykodnyi

Keyword(s):

Performance Indicator ◽

Optimization Problems ◽

Economic Effect ◽

Unit Cost ◽

Maximum Level ◽

Technological Parameters ◽

Goods And Services ◽

The Third ◽

Use Of Resources ◽

The Moment

The article investigates the existing trends and prospects for the development of warehousing services in the system of production and processing of products, which allowed us to form the purpose of the research in this development. The chosen theme is quite topical, because warehousing processes are an integral part of the formation of supply logistics in modern production processes. One of the ways to reduce the cost of goods and services is the efficient use of resources. Ukrainian and foreign scientists have touched many questions concerning the development of the infrastructure component, solutions of optimization problems regarding the process of import-export of goods to the warehouse, but without determining the optimal values of technological parameters of warehousing systems. The technological scheme of operation of the warehouse system of the enterprise LLC "MEGA CRISP» allows to see the whole chain of operations from the moment of arrival of the vehicle with cargo (containers and packaging) to the moment of sending the cargo (finished product) to the recipient; the necessary types of resources involved in these processes are also taken into account. Total costs were chosen as an evaluation indicator of the choice of an efficient supply channel. Relevant parameters of influence are taken into account: intensities of corresponding cargo flows, unit cost of the appropriate work and one hour of work of one worker, time of performance of an appropriate operation, quantity of the involved resources for performance of the appropriate operation and working time of the warehouse during the day. An imitation full-factor experiment was performed, based on the results of which a regression model in linear form with a non-zero coefficient was determined, in which each coefficient indicates the degree of influence of the relevant factor on the performance indicator. The results of determining the economic effect showed that "Variant 2" (increasing the number of workers) is the least expensive, and the level of costs is lower for all series of experiments compared to the basic variant - "Variant 1". The maximum difference is reached in 12217.8 hryvnias at the maximum loading of a warehouse. And when comparing the third and first variants: only at the maximum level of output flow (170 t / h), the third variant will be cheaper by 852.6 hryvnias. The highest level of positive value of the effect among the variants offered is "Variant 2", the level of savings will be 12,217.8 hryvnias per shift.

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