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In this paper we have inferred the magnetic shielding characteristics and space weather hazards of selected potentially habitable extrasolar planets using a dynamical geophysical model from calculations of internal heat, phases of volcanism and planetary magnetic moments. The space weather hazards on the extrasolar planet Kepler-452b orbiting around a Sun-like star are found to be a minimum which enhances the habitability probability of this planet.
We present Ekster, a new method for simulating the formation and dynamics of individual stars in a relatively low-resolution gas background. Here, we use Ekster to simulate star cluster formation in two different regions from each of two galaxy models with different spiral potentials. We simulate these regions for 3 Myr to study where and how star clusters form. We find that massive GMC regions form more massive clusters than sections of spiral arms. Additionally we find that clusters form both by accreting gas and by merging with other proto-clusters, the latter happening more frequently in the denser GMC regions.
The Laser Interferometer Space Antenna (LISA) mission will observe from space gravitational waves emitted by neutron stars and white dwarfs within galactic binaries. These compact stars can have intense magnetic fields. Therefore, the impact of the magnetic fields on the orbital and the spins evolution of binary systems can potentially be detected by LISA through the GW’s strain. Within the magnetic dipole-dipole approximation, we found that magnetism generates a secular drift of the mean longitude which, in turn, shifts all the frequencies contained in the GW signal. For a quasi-circular orbit, the signal is mainly monochromatic and the magnetic shift is proportional to the product of the magnetic moments and is inversely proportional to the 7/2 power of the semi-major axis. Hence, for a highly magnetic binary system in compact orbit, a non-negligible amount of the frequency measured by LISA might have a magnetic origin.
One of the models explaining the high luminosity of pulsing ultra-luminous X-ray sources (pULXs) was suggested by Mushtukov et al. (2015). They showed that the accretion columns on the surfaces of highly magnetized neutron stars can be very luminous due to opacity reduction in the high magnetic field. However, a strong magnetic field leads also to amplification of the electron-positron pairs creation. Therefore, increasing of the electron and positron number densities compensates the cross-section reduction, and the electron scattering opacity does not decrease with the magnetic field magnification. As a result, the maximum possible luminosity of the accretion column does not increase with the magnetic field. It ranges between 1040 − 1041 erg s−1 depending only slightly on the magnetic field strength.
In recent years, an increasing amount of attention is being paid to the gravitational few-body problem and its applications to astrophysical scenarios. Among the main reasons for this renewed interest there is large number of newly discovered exoplanets and the detection of gravitational waves. Here, we present two numerical codes to model three- and few-body systems, called tsunami and okinami. The tsunami code is a direct few-body code with algorithmic regularization, tidal forces and post-Newtonian corrections. okinami is a secular, double-averaged code for stable hierarchical triples. We describe the main methods implemented in our codes, and review our recent results and applications to gravitational-wave astronomy, planetary science and statistical escape theories.
Space interferometry is the inevitable end point of high angular resolution astrophysics, and a key technology that can be leveraged to analyse exoplanet formation and atmospheres with exceptional detail. However, the anticipated cost of large missions, such as Darwin and TPF-I, and inadequate technology readiness levels have resulted in limited developments since the late 2000s. Here, we present a feasibility study into a small-scale formation-flying interferometric array in low Earth orbit, which will aim to prove the technical concepts involved with space interferometry while still making unique astrophysical measurements. We will detail the proposed system architecture and metrology system, as well as present orbital simulations that show that the array should be stable enough to perform interferometry with <50 m s–1 yr–1 delta-v and one thruster per spacecraft. We also conduct observability simulations to identify which parts of the sky are visible for a given orbital configuration. We conclude with optimism that this design is achievable, but a more detailed control simulation factoring in a demonstrated metrology system is the next step to demonstrate full mission feasibility.
We present SimSpin, a new, public, software framework for generating integral field spectroscopy (IFS) data cubes from N-body/hydrodynamical simulations of galaxies, which can be compared directly with observational datasets. SimSpin provides a consistent method for studying a galaxy’s stellar component. It can be used to explore how observationally inferred measurements of kinematics, such as the spin parameter
$\lambda_R$
, are impacted by the effects of, for example, inclination, seeing conditions, distance. SimSpin is written in R and has been designed to be highly modular, flexible, and extensible. It is already being used by the astrophysics community to generate IFS-like cubes and FITS files for direct comparison of simulations to observations. In this paper, we explain the conceptual framework of SimSpin; how it is implemented in R; and we demonstrate SimSpin’s current capabilities, providing as an example a brief investigation of how numerical resolution affects how reliably we can recover the intrinsic stellar kinematics of a simulated galaxy.
Here one can learn some theory and practice of symplectic integration. The basic idea is that every integration step should be a canonical transformation, because that is what motion in a Hamiltonian system is.
The gravitational field of a black hole differs significantly from the point-mass field that is normally used in N-Body simulations. The additional terms needed are called Post-Newtonian ones and abbreviated as PN-terms. They depend in addition of coordinates also on velocities. Thus the methods discussed in Section~\ref{v-dependence} must be used in numerical integration. An other problem is that the orbital elements of two-body motions cannot any more be evaluatedin the same way as in the Newtonian point-mass dynamics. Finally one must remember that black holes rotate and form a so called Kerr-hole that produce a fielddiffering from the non-rotating one and the rotation, the black hole spin, changes due to interactions withother bodies. These complexities is discussed and formulae given in this short chapter
The main theme in this chapter is Algorithmic Regularization.The procedures in this are the {Logarithmic Hamiltonian (LogH)} and the {Time Transformed Leapfrog (TTL)}, in both of which the use of {\bf leapfrog is compulsory for regularization}. In addition to this, auxiliary variables for velocity dependent perturbations are specified.
This chapter discusses the various problems of few-body dynamics, starting from the two-body and planetary systems and proceeds to stellar dynamics and artificial satellite motions.
This chapter discusses the basic concepts in many-body dynamics.From the Lagrangian, Hamiltonian, canonical transformations and time transformations to Hamilton-Jacobi equations. This content can be found in most classical dynamics textbooks
This chapter is essentially a partial copy of the manuscript for the paper Mikkola, Palmer, Hashida(2002). In fact the text is mostly from the manuscript for that paper. A method of high precision computation of the motion of a body in a potential witch is an expansion in terms ofspherical harmonics, is considered.