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The solar neighbourhood contains disc stars that have recently crossed spiral arms in the Galaxy. We propose that boundaries in local velocity distributions separate stars that have recently crossed and been more strongly perturbed by a particular arm from those that haven't. Ridges in the stellar velocity distributions constructed from the second Gaia data release trace orbits that could have tou
We explore the connections between stellar age, chemistry, and kinematics across a Galactocentric distance of 7.5 < R(kpc) < 9.0, using a sample of ~12 000 intermediate-mass (FGK) turn-offstars observed with the RAdial Velocity Experiment (RAVE) survey. The kinematics of this sample are determined using radial velocity measurements from RAVE, and parallax and proper motion measurements from the T
We characterize the selection function of RAdial Velocity Experiment (RAVE) using 2 Micron All Sky Survey (2MASS) as our underlying population, which we assume represents all stars that could have potentially been observed.We evaluate the completeness fraction as a function of position, magnitude and colour in two ways: first, on a field-by-field basis, and second, in equal-size areas on the sky.
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The nuclear stellar disc (NSD) is a flattened high-density stellar structure that dominates the gravitational field of the Milky Way at Galactocentric radius $30\, {\rm pc}\lesssim R\lesssim 300\, {\rm pc}$. We construct axisymmetric self-consistent equilibrium dynamical models of the NSD in which the distribution function is an analytic function of the action variables. We fit the models to the n
Zinc is an element of importance in many research fields within astronomy and astrophysics, from cosmology to stellar atmosphere dynamics. With the aim of improving three decades old measurements of zinc lines of astrophysical interest, emission spectra of Zn I and Zn II have been recorded using a Fourier Transform Spectrometer with a hollow cathode light source. Revised energies for previously kn
Spectral lines observed in the Sr-filament of eta Car in the wavelengthregion 2480-10140{AA}. The lines are sorted by wavelength in table 2 andsorted according to the periodic table in table 3. Both tables areavailable in postscript format as the file tables23.ps where the sub andsuperscripts for the atomic transitions are kept.(2 data files).
Context. The planet-metallicity correlation for gaseous giants is widely accepted through spectroscopic studies. However, whether a similar correlation exists for terrestrial planets is a debated subject. High-precision spectroscopic abundance analysis on Sun-like stars suggested that the Sun is depleted in refractory elements with respect to its solar twins without exoplanets, likely due to the f
Orbital or mean motion resonance (MMR) occurs when the orbital period ratio between two planets is close to a ratio of small integers. MMR can protect planets from collisions and affects the overall final architecture of the system. Observations of exoplanets have shown that the survival rate of MMR-chains is low, and most systems are near and just wide of an exact MMR. The most common chains are
Binary planetesimals in the Kuiper belt can experience close encounters with other bodies. These encounters can disturb the orbital dynamics of the binary in several ways. Energy can be added to the system by the impactor body and lead to the disruption of the binary. Less energetic encounters can alter the orbital elements of the mutual orbit of the binary. The impactor could swap with one of the
The Laser Interferometer Space Antenna (LISA) is a space borne gravitational wave detec- tor set to launch in 2034, with the objective of detecting and studying the Gravitational Waves (GWs) of our universe. So far, ground-based detectors such as the Laser Interferometer Gravitational-Wave Observatory (LIGO) have been successful in detecting GWs, but the limitations of ground based detectors is wh
Stellar streams around the Milky Way (MW) have been observed by wide sky surveys, and studied to understand the mass distribution of the MW. This is because streams are formed by a disruption of a globular cluster or a dwarf galaxy under the influence of the gravitational field of the MW. Moreover, the streams can provide an understanding of dark matter because they orbit in the far outer region o
Carbon is the fourth most abundant element after hydrogen, helium and oxygen. It is a product of stellar nucleosynthesis as well as it being an important bio signature for life; this makes the analysis of carbon very fundamental. The origin of carbon and the relative contributions from massive and low-to-intermediate mass stars in producing it is still under debate. The principal focus of this the
Double neutron star binaries (DNSBs) in the mHz gravitational wave (GW) regime are an important group of objects which the GW detector LISA will be able to observe. The detection and parametrization of these objects will help develop our current understanding of neutron star formation and evolution. In this thesis, we synthesize a group of DNSBs using data from Church et al. (2011) and normalize t
Using methods of smoothed particle hydrodynamics (SPH) an N -body simulation was set-up to investigate stellar encounters between a 1 solar-mass main sequence (MS) star, modeled after the Sun, and a 0.6 solar-mass white dwarf (WD). This was done primarily to investigate the assumptions made by Mastrobuono-Battisti et al. (2021) in search of the impact of stellar encounters on stellar population in
Studies of the Milky Way including how it formed and evolved through time are the key to understanding how other galaxies behave. The Milky Way is the most convenient galaxy to study, because the close proximity of stars means astronomers can collect precise spectral and dynamical data from individual stars. By combining the chemical and dynamical aspects, it is possible to pinpoint stars which ha
We present simulations done on the onset of common envelope evolution with giant donors by taking into account the mass loss through the outer Lagrange point and the forming of the common envelope. In addition we apply proper stellar models and evolve our simulations using an Runge-Kutta integrator with adaptive step-size. We show that each of these processes are significant in the onset of common
