Essays about: "gravitational instability"

Found 5 essays containing the words gravitational instability.

  1. 1. The quest for a classical bulge - a study of kinematics, abundances, and ages using microlensed dwarf stars and Gaia

    University essay from Lunds universitet/Astrofysik; Lunds universitet/Fysiska institutionen

    Author : Calum Kvernes Macpherson; [2023]
    Keywords : Bulge; Milky Way; Kinematics; Galpy; Dwarf Stars; Physics and Astronomy;

    Abstract : Context: We present an kinematical analysis of 90 F and G type dwarf, turn-off, and subgiant stars in the Galactic bulge. These stars were observed with high-resolution spectrographs during gravitational microlensing events This allowed for their ages, abundances, and radial velocities to be ascertained while they were significantly brighter. READ MORE

  3. 2. Superradiant axion clouds and their interaction with astrophysical plasma

    University essay from KTH/Fysik

    Author : Erik Engstedt; [2021]
    Keywords : axions; superradiance; black holes; black hole accretion; astrophysical plasma; axioner; strålningsförstärkning; svarta hål; svart hålansamling; astrofysikalisk plasma;

    Abstract : Axions are one of the best-motivated particles beyond the standard model of particle physics and a promising candidate for dark matter. Through the superradiant instability, axions can extract a significant amount of rotational energy from spinning black holes resulting in dense axion clouds. READ MORE

  4. 3. Stars Eating Planets

    University essay from Lunds universitet/Astronomi - Genomgår omorganisation

    Author : John Wimarsson; [2020]
    Keywords : Earth and planetary astrophysics; planetary dynamics; planet-planet scattering; planet consumption; Physics and Astronomy;

    Abstract : In a phase of instability during the dynamical evolution of some multiple exoplanetary systems, exchange of angular momentum and/or energy through gravitational interactions between planets will lead to alterations of their orbital properties. In some cases, planetary orbits end up crossing, which leads to close encounters between two planets. READ MORE

  5. 4. Investigating Gas Turbulence in Galactic Discs

    University essay from Lunds universitet/Astronomi - Genomgår omorganisation

    Author : Timmy Ejdetjärn; [2019]
    Keywords : galaxies; gas; turbulence; interstellar medium; star formation; feedback; gravitational instability; local; high redshift; Physics and Astronomy;

    Abstract : The interstellar medium of both local and distant disc galaxies is observed to be supersonically turbulent and the turbulent motion of the gas is thought to be important for galaxy formation and evolution, particularly as a key ingredient for star formation. Consequently, this generates a striking relation between the star formation rate (SFR) and gas velocity dispersion ($\sigma_{\rm g}$; a measurement on the level of turbulence). READ MORE

  6. 5. Ice condensation as a planet formation mechanism

    University essay from Lunds universitet/Astronomi - Genomgår omorganisation; Lunds universitet/Institutionen för astronomi och teoretisk fysik - Genomgår omorganisation

    Author : Katrin Ros; [2012]
    Keywords : Physics and Astronomy;

    Abstract : In models of dust growth in protoplanetary discs focus is typically on coagulation, a mechanism which unfortunately seems incapable of forming particles larger than centimeters. The main reasons for this are that collisions between larger particles lead to bouncing or fragmentation rather than sticking, and that particles approaching meter-sizes drift radially inwards in the disc due to interaction with the surrounding gas. READ MORE