scholarly journals Investigating Optimizing Mirror Orbits for Dark-side Illumination

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Kaisa Elisabeth Anne Crawford-Taylor
Keyword(s):  
Large Scale ◽  
Satellite Orbit ◽  
Dark Side ◽  
Satellite Orbits ◽  
Low Mass Stars ◽  
Earth Like Planets ◽  
Low Mass ◽  
Side Illumination ◽  
Selection Of

When a planet is tidally locked with its star, the same side always faces the star; thus one side is always dark. This synchronization occurs quickly for potentially habitable Earth-like planets orbiting dim, low-mass stars. Korpela, Sallmen, & Leystra Greene (2015; KSG) suggest that advanced extraterrestrial civilizations may put large-scale mirror fleets in orbit around such exoplanets to reflect starlight to the dark side of the planet. They might also use such mirrors to alter the climate of their own or another planet. Radiation pressure (RP) will be important for such large, lightweight mirrors, but research on satellite orbit stability typically neglects its effects. The long-term goal of this research is to determine fuel-efficient satellite orbits in situations where RP is important. We use Python and REBOUND to simulate mirrors orbiting an Earth-like exoplanet in the habitable zone for a variety of stars. Our simulations use two settings: “Always RP” always reflects starlight towards the planet’s center while “Nighttime RP” only does so on its dark side. We found mirrors survive longer when initially orbiting face on to the star compared to edge on. We present a selection of results illustrating how RP affects the mirror’s survival time.

scholarly journals A LARGE-SCALE OPTICAL-NEAR-INFRARED SURVEY FOR BROWN DWARFS AND VERY LOW MASS STARS IN THE ORION OB1 ASSOCIATION

2008 ◽  
Vol 136 (1) ◽  
pp. 51-66 ◽  
Author(s):  
Juan José Downes ◽  
César Briceño ◽  
Jesús Hernández ◽  
Nuria Calvet ◽  
Lee Hartmann ◽  
...  
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Brown Dwarfs ◽  
Low Mass Stars ◽  
Low Mass ◽  
Infrared Survey

scholarly journals Perspectives on the Capabilities for the Selection of Strategic Projects

2020 ◽  
Vol 12 (19) ◽  
pp. 8191
Author(s):  
Khalifa Mohammed Al-Sobai ◽  
Shaligram Pokharel ◽  
Galal M. Abdella
Keyword(s):  
Large Scale ◽  
Quantitative Methods ◽  
Project Selection ◽  
Economic Benefits ◽  
Research Directions ◽  
Qualitative And Quantitative Methods ◽  
Strategic Project ◽  
Managerial Capabilities ◽  
Selection Of

Strategic projects are large scale, complex, and require significant investments and resources. These projects aim at gaining long-term social and economic benefits. Therefore, organizations focusing on strategic projects should use a consistent approach that suits their strategy, capability, and long-term expectations. Based on the four research questions and content analysis of the literature, generic processes used for the strategic project selection in tandem with the managerial capabilities are identified in this paper. The generic processes and managerial capabilities are used to develop a generic framework for strategic project selection. The framework is used for literature analysis in the paper. The review shows that both qualitative and quantitative methods are used for strategic project selection. Some possible research directions have also been proposed at the end of the review. The paper provides value to both researchers and practitioners in terms of tools available and a guidance on project selection through a structured process framework.

scholarly journals The Reaction of Low-Mass Stars to Anisotropic Irradiation and its Implications for the Secular Evolution of Cataclysmic Binaries

1996 ◽  
Vol 165 ◽  
pp. 65-71
Author(s):  
H. Ritter ◽  
Z. Zhang ◽  
U. Kolb
Keyword(s):  
Mass Transfer ◽  
Time Scale ◽  
Mass Transfer Rate ◽  
Mass Star ◽  
Evolutionary Time ◽  
Low Mass Stars ◽  
Secular Evolution ◽  
Cataclysmic Binaries ◽  
Low Mass

A semi-analytic model for the reaction of a low-mass star to anisotropic irradiation of low incident flux is presented. By applying this model to the donor star of cataclysmic binaries (CBs) it is shown that CBs are likely to be unstable against irradiation-driven runaway mass transfer. The implications of this instability for the long-term evolution of CBs are examined. The possibility is discussed that because of this instability CBs evolve through a limit cycle in which phases of high and low mass transfer rate alternate on a time scale short compared to the evolutionary time scale.

scholarly journals The Dark Side of Globular Clusters

1996 ◽  
Vol 174 ◽  
pp. 377-378
Author(s):  
P.-Y. Longaretti ◽  
R. Taillet ◽  
P. Salati
Keyword(s):  
Globular Clusters ◽  
Mass Function ◽  
Dynamical Analysis ◽  
Dark Side ◽  
Low Mass Stars ◽  
First Results ◽  
Low Mass ◽  
Non Parametric

Searches of low-mass stars have become possible in globular clusters, and the first results suggest that the mass function turns up below ∼ 0.4 M⊙ (Fahlman et al. 1989; Richer et al., 1990; Richer et al. 1991; G. Piotto, these proceedings). This conclusion is independently supported by the non-parametric dynamical analysis of four clusters by Gebhardt and Fisher 1995.

scholarly journals Does magnetic field impact tidal dynamics inside the convective zone of low-mass stars along their evolution?

2019 ◽  
Vol 631 ◽  
pp. A111 ◽  
Author(s):  
A. Astoul ◽  
S. Mathis ◽  
C. Baruteau ◽  
F. Gallet ◽  
A. Strugarek ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Scaling Laws ◽  
Low Mass Stars ◽  
Convective Envelope ◽  
Tidal Waves ◽  
Short Period ◽  
Tidal Flows ◽  
Low Mass ◽  
The Impact

Context. The dissipation of the kinetic energy of wave-like tidal flows within the convective envelope of low-mass stars is one of the key physical mechanisms that shapes the orbital and rotational dynamics of short-period exoplanetary systems. Although low-mass stars are magnetically active objects, the question of how the star’s magnetic field impacts large-scale tidal flows and the excitation, propagation and dissipation of tidal waves still remains open. Aims. Our goal is to investigate the impact of stellar magnetism on the forcing of tidal waves, and their propagation and dissipation in the convective envelope of low-mass stars as they evolve. Methods. We have estimated the amplitude of the magnetic contribution to the forcing and dissipation of tidally induced magneto-inertial waves throughout the structural and rotational evolution of low-mass stars (from M to F-type). For this purpose, we have used detailed grids of rotating stellar models computed with the stellar evolution code STAREVOL. The amplitude of dynamo-generated magnetic fields is estimated via physical scaling laws at the base and the top of the convective envelope. Results. We find that the large-scale magnetic field of the star has little influence on the excitation of tidal waves in the case of nearly-circular orbits and coplanar hot-Jupiter planetary systems, but that it has a major impact on the way waves are dissipated. Our results therefore indicate that a full magneto-hydrodynamical treatment of the propagation and dissipation of tidal waves is needed to properly assess the impact of star-planet tidal interactions throughout the evolutionary history of low-mass stars hosting short-period massive planets.

Circumstellar disk fragmentation and the origin of massive planetary companions, brown dwarfs, and very low-mass stars

2018 ◽  
Vol 14 (S345) ◽  
pp. 239-240 ◽  
Author(s):  
M. B. N. Kouwenhoven ◽  
Yun Li ◽  
D. Stamatellos ◽  
S. P. Goodwin
Keyword(s):  
Binary Systems ◽  
Brown Dwarfs ◽  
Mass Range ◽  
Mass Function ◽  
Initial Mass Function ◽  
Low Mass Stars ◽  
Triple Systems ◽  
Low Mass ◽  
Viable Mechanism

AbstractThe low-mass end of the initial mass function remains poorly understood. In this mass range, very low-mass stars, brown dwarfs, and massive planets are able to form through a variety of physical processes. Here, we study the long-term evolution of disk-fragmented systems around low-mass stars, for the epoch up to 10 Myr (the typical lifetime of an embedded cluster) and up to 10 Gyr (the age of the Milky Way). We carry out N-body simulations to study the decay of disk-fragmented systems and the resulting end products. Our simulations indicate rapid decay and frequent physical collisions during the first 10 Myr. We find that disk fragmentation provides a viable mechanism for explaining hierarchical triple systems, the brown dwarf desert, single and binary brown dwarfs, and very low-mass binary systems in the solar neighbourhood.

scholarly journals Deep inside low-mass stars

2008 ◽  
Vol 4 (S252) ◽  
pp. 163-174 ◽  
Author(s):  
Corinne Charbonnel ◽  
Suzanne Talon
Keyword(s):  
Large Scale ◽  
Main Sequence ◽  
Internal Gravity Waves ◽  
Transport Processes ◽  
Atomic Diffusion ◽  
Physical Processes ◽  
Low Mass Stars ◽  
Low Mass ◽  
Stellar Properties ◽  
The Impact

AbstractLow-mass stars exhibit, at all stages of their evolution, the signatures of complex physical processes that require challenging modeling beyond standard stellar theory. In this review, we recall the most striking observational evidences that probe the interaction and interdependence of various transport processes of chemicals and angular momentum in these objects. We then focus on the impact of atomic diffusion, large scale mixing due to rotation, and internal gravity waves on stellar properties on the main sequence and slightly beyond.

scholarly journals Disk Mass From Large-Scale Dynamics

1998 ◽  
Vol 11 (1) ◽  
pp. 410-411
Author(s):  
J.A. Sellwood
Keyword(s):  
Dark Matter ◽  
Large Scale ◽  
Stellar Population ◽  
Milky Way ◽  
Low Mass Stars ◽  
Rutgers University ◽  
Disk Mass ◽  
Low Mass ◽  
The Individual ◽  
Inner Parts

The radial distribution of mass in a disk galaxy is strongly constrained by its rotation curve. The separate contributions from the individual stellar populations and dark matter (DM) are not easily disentangled, however, especially since there is generally no feature to indicate where the component dominating the central attraction switches from luminous to dark matter. Here I summarize three recent thesis projects at Rutgers University which all suggest that DM has a low density in the inner parts of bright galaxies, and that most of the mass therefore resides in the disk. In addition, I present some preliminary work on the Milky Way. If we are able to determine the M/L of a typical disk stellar population, it should provide a useful constraint on the numbers of low mass stars.

Sign in / Sign up

Export Citation Format

Share Document