Publicação
Modelling the Evolution of the Galactic Disk Scale Height Traced by Open Clusters
| Resumo: | To understand how galaxies evolve, it is crucial to track their morphological changes and identify the underlying mechanisms that drive them. Of particular interest to parameterize the disk, is the scale height of the vertical distribution of objects, above and below the Galactic plane, describes the thickness of the disk. Although the study of thickness of the disk can be made with different objects (e.g stars), open clusters are often used as disk probes due to the precision with which their distances and ages can be determined, making them key astrophysical objects for studying the morphological changes and evolution of our Galaxy. The scale height of the spatial distribution of open clusters in the Milky Way exhibits a well known increase with age. This increase is usually attributed, in a vague way, to disc heating mechanisms similar to those that act on individual stars or that the disk was thicker in the past. In this work, we address the evolution of the scale height of open clusters from a different angle, as an effect of the disruption of clusters due to disc phenomena such as encounters with giant molecular clouds. We present a dynamical model that follows the orbits of open clusters and includes their disruption due to interactions with the disc and mass loss due to stellar evolution and evaporation. The results show that the proposed model is a viable mechanism to explain the evolution of the scale height of open clusters. Additionally, the model is also able to predict the total number of open clusters that survive with age, indicating that the timescale of the disruption is being successfully reproduced. We identify additional features that can be added in the future to improve the model, namely mass dependent disruption by giant molecular clouds and initial cluster velocities. |
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| Autores principais: | Moreira, Sandro Miguel Ferreira |
| Assunto: | aglomerado aberto galáxia disco escala de altura gigantes moleculares Teses de mestrado - 2024 |
| Ano: | 2024 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | To understand how galaxies evolve, it is crucial to track their morphological changes and identify the underlying mechanisms that drive them. Of particular interest to parameterize the disk, is the scale height of the vertical distribution of objects, above and below the Galactic plane, describes the thickness of the disk. Although the study of thickness of the disk can be made with different objects (e.g stars), open clusters are often used as disk probes due to the precision with which their distances and ages can be determined, making them key astrophysical objects for studying the morphological changes and evolution of our Galaxy. The scale height of the spatial distribution of open clusters in the Milky Way exhibits a well known increase with age. This increase is usually attributed, in a vague way, to disc heating mechanisms similar to those that act on individual stars or that the disk was thicker in the past. In this work, we address the evolution of the scale height of open clusters from a different angle, as an effect of the disruption of clusters due to disc phenomena such as encounters with giant molecular clouds. We present a dynamical model that follows the orbits of open clusters and includes their disruption due to interactions with the disc and mass loss due to stellar evolution and evaporation. The results show that the proposed model is a viable mechanism to explain the evolution of the scale height of open clusters. Additionally, the model is also able to predict the total number of open clusters that survive with age, indicating that the timescale of the disruption is being successfully reproduced. We identify additional features that can be added in the future to improve the model, namely mass dependent disruption by giant molecular clouds and initial cluster velocities. |
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