How Do The Effects Of Radial Migration Induced By Transient Spiral Arms In A Milky Way-like Galaxy Impact The Observed Metallicity And Age Distributions Of Stars In The Galactic Thick Disk, Particularly For Stars With [Fe/H] > -1.0 And Ages Between 8-12 Gyr?

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Radial migration induced by transient spiral arms in a Milky Way-like galaxy significantly impacts the observed metallicity and age distributions of stars in the galactic thick disk, particularly for stars with [Fe/H] > -1.0 and ages between 8-12 Gyr. Here's a structured summary of the effects:

  1. Radial Migration and Mixing: Transient spiral arms facilitate the movement of stars from different birth radii into the thick disk. This process mixes stars from various regions, leading to a more homogeneous stellar population in terms of metallicity and age.

  2. Metallicity Distribution:

    • The thick disk is typically metal-poor, but radial migration introduces metal-rich stars ([Fe/H] > -1.0) from the inner galaxy, where higher metallicity is achieved sooner due to more efficient star formation.
    • This results in a broader metallicity range in the thick disk, flattening the metallicity gradient that would otherwise be steeper without migration.

  3. Age Distribution:

    • The age range of 8-12 Gyr suggests these stars formed early in the galaxy's history. Radial migration can bring older stars from the inner regions into the thick disk, potentially homogenizing the age distribution within this range.
    • The observed ages reflect the timing of spiral arm activity and migration events, which likely occurred early, contributing to the thick disk's formation.

  4. Formation and Evolution:

    • The thick disk, formed through processes like heating of an older thin disk, is influenced by early radial migration events. These events transport stars formed in metal-rich inner regions to the thick disk, enriching its metallicity.
    • The migration aligns with the early formation of the thick disk, indicating that these stars' current positions result from both their birthplace and subsequent migration.

In conclusion, radial migration from transient spiral arms leads to a more mixed stellar population in the thick disk, with metal-rich stars ([Fe/H] > -1.0) and ages of 8-12 Gyr reflecting early formation in the inner galaxy followed by outward migration. This process broadens the metallicity distribution and homogenizes the age distribution within the specified range.