How are stellar streams detected and mapped in the Milky Way?
Stellar streams are detected and mapped in the Milky Way using a combination of deep imaging surveys and astrometric data, such as from the Gaia mission, to measure the positions, motions, and velocities of stars. These data help identify coherent groups of stars with similar kinematics and metallicities, tracing the remnants of disrupted satellite galaxies or star clusters.
What causes stellar streams to form?
Stellar streams form when gravitational interactions pull stars away from a disrupted satellite galaxy, such as a dwarf galaxy or a globular cluster, as it orbits a larger galaxy like the Milky Way. These tidal forces stretch the stripped stars into elongated structures along the satellite's orbit, creating stellar streams.
What information do stellar streams provide about the history and evolution of galaxies?
Stellar streams provide insights into the gravitational interactions and merger history of galaxies, revealing past galaxy collisions and accretion events. They trace the distribution of dark matter, helping to map the galaxy’s gravitational potential. Stream kinematics offer clues about the Milky Way’s formation and how its structure has evolved over time.
How do stellar streams impact the overall structure and dynamics of their host galaxy?
Stellar streams contribute to the overall structure and dynamics of their host galaxy by providing evidence of past interactions and mergers. They influence the distribution of dark matter, trace gravitational potential, and enrich the galactic halo with stars, thereby impacting the galaxy's evolution and mass distribution.
Can stellar streams be used to determine the presence of dark matter in galaxies?
Yes, stellar streams can be used to determine the presence of dark matter in galaxies by tracking their movements and gravitational interactions. The analysis of the stream's orbit and density disruptions can provide insights into the dark matter distribution and potential clumps within the galaxy.