The Age-Dependent Vertical Actions of Young Stars in the Galaxy
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| Main Authors: | , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866911950750875648 |
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| author | Garzon, D. N. Frankel, Neige Zari, Eleonora Xiang, Maosheng Rix, Hans-Walter |
| author_facet | Garzon, D. N. Frankel, Neige Zari, Eleonora Xiang, Maosheng Rix, Hans-Walter |
| contents | Stars in the Galactic disk are born on cold, nearly circular orbits with small vertical excursions. After their birth, their orbits evolve, driven by small- or large-scale perturbations in the Galactic disk's gravitational potential. Here, we study the vertical motions of young stars over their first few orbital periods, using a sample of OBA stars from \textit{Gaia} E/DR3, which includes radial velocities and ages $τ$ from LAMOST. We constructed a parametric model for the time evolution of the stellar orbits' mean vertical actions $J_z$ as a function of Galactocentric radius, $R_{\mathrm{GC}}$.
Accounting for data uncertainties, we use Markov Chain Monte Carlo (MCMC) analysis in annuli of Galactocentric radius to constrain the model parameters. Our best-fit model shows a remarkably linear increase of vertical actions with age across all Galactocentric radii examined. Orbital \textit{heating} by random scattering could offer a straightforward interpretation for this trend. However, various other dynamical aspects of the Galactic disk, such as stars being born in a warped disk, might offer alternative explanations that could be tested in the future. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2407_07323 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | The Age-Dependent Vertical Actions of Young Stars in the Galaxy Garzon, D. N. Frankel, Neige Zari, Eleonora Xiang, Maosheng Rix, Hans-Walter Astrophysics of Galaxies Stars in the Galactic disk are born on cold, nearly circular orbits with small vertical excursions. After their birth, their orbits evolve, driven by small- or large-scale perturbations in the Galactic disk's gravitational potential. Here, we study the vertical motions of young stars over their first few orbital periods, using a sample of OBA stars from \textit{Gaia} E/DR3, which includes radial velocities and ages $τ$ from LAMOST. We constructed a parametric model for the time evolution of the stellar orbits' mean vertical actions $J_z$ as a function of Galactocentric radius, $R_{\mathrm{GC}}$. Accounting for data uncertainties, we use Markov Chain Monte Carlo (MCMC) analysis in annuli of Galactocentric radius to constrain the model parameters. Our best-fit model shows a remarkably linear increase of vertical actions with age across all Galactocentric radii examined. Orbital \textit{heating} by random scattering could offer a straightforward interpretation for this trend. However, various other dynamical aspects of the Galactic disk, such as stars being born in a warped disk, might offer alternative explanations that could be tested in the future. |
| title | The Age-Dependent Vertical Actions of Young Stars in the Galaxy |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2407.07323 |