Chemical complexity in simulations of circumstellar discs formation. Modeling complex chemical evolution in star forming regions.
Loading...
Date
2025
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
La química desempeña un papel crucial en la formación y evolución de los sistemas estelares, por lo que resulta esencial estudiar el estado químico en regiones de formación estelar mediante simulaciones numéricas. A pesar de su importancia, modelar de networks químicas complejas en simulaciones es un proceso computacionalmente costoso debido al gran número de reacciones y especies implicadas. Para hacer frente a este reto, esta tesis emplea un marco de post-procesamiento para incorporar química compleja en simulaciones sph de alta resolución. Utilizando el paquete astroquímico Krome, modelamos la evolución de química a lo largo de la historia dinámica de las partículas a partir de simulaciones preexistentes, centrándonos en reacciones en fase gaseosa y de polvo relevantes para la formación y evolución de especies portadoras de H − C − O, hasta la formación de metanol (CH3OH).
En este estudio investigamos la complejidad química de los discos circunestelares formados dentro de un cúmulo de formación estelar. Analizando la estructura vertical de estos discos, identificamos regiones de mayor actividad química y exploramos la distribución espacial de moléculas orgánicas complejas. Nuestros resultados revelan que el metanol, una molécula clave para evaluar la posible complejidad química en regiones de formación estelar, se localiza predominantemente dentro de los discos circunestelares en su fase gaseosa, particularmente en aquellos que rodean objetos estelares más antiguos. Se observaron altas concentraciones de metanol en regiones del disco donde las condiciones físicas no favorecen la formación de esta molécula. Este fenómeno se atribuye al proceso de acreción de material en el disco, en el que las regiones de baja temperatura permiten la formación de metanol en los granos de polvo, que posteriormente se desorbe a la fase gaseosa a medida que el material se acreta hacia las regiones internas del disco, donde las temperaturas superan los 104 K.
Este trabajo establece una metodología robusta para integrar química compleja en simulaciones astrofísicas mediante técnicas de postprocesado. Al proporcionar una network química actualizada que incluye reacciones en granos de polvo, ofrece una base para futuros estudios destinados a investigar la evolución química en regiones de formación estelar y discos circunestelares.
Chemistry plays a crucial role in the formation and evolution of stellar systems, making it essential to study the chemical state of star-forming regions through numerical simulations. Despite its significance, modeling complex chemical networks within simulations is a computationally expensive process due to the large number of reactions and species involved. To address this challenge, this thesis employs a post-processing framework to incorporate complex chemistry into high-resolution smoothed particle hydrodynamics (SPH) simulations. Using the astrochemical package Krome, we model the evolution of chemistry along the dynamical history of particles from pre-existing simulations, focusing on gas and dust-phase reactions relevant to the formation and evolution of H − C − O bearing species, up to the formation of methanol (CH3OH). In this study we investigated the chemical complexity of circumstellar discs formed within a simulated star-forming cluster. By analyzing the vertical structure of these discs, we identify regions of enhanced chemical activity and explore the spatial distribution of complex organic molecules. Our results reveal that methanol, a key molecule to assess the possible chemical complexity in star-forming regions, is predominantly located within circumstellar discs in its gas-phase, particularly those surrounding older stellar objects. Unexpectedly, high concentrations of methanol were observed in regions of the disc where the physical conditions do not favor the formation of this molecule. This phenomenon is attributed to the accretion process, wherein low-temperature regions allow the formation of methanol on dust grains, which subsequently desorbs into the gas phase as material is accreted into the inner disc regions where temperatures exceed 104 K. This work sets a robust methodology for integrating complex chemistry into astrophysical simulations via post-processing techniques. By providing an up-to date chemical network that includes surface reactions, it offers a foundation for future studies aiming to investigate the chemical evolution of star-forming regions and circumstellar discs.
Chemistry plays a crucial role in the formation and evolution of stellar systems, making it essential to study the chemical state of star-forming regions through numerical simulations. Despite its significance, modeling complex chemical networks within simulations is a computationally expensive process due to the large number of reactions and species involved. To address this challenge, this thesis employs a post-processing framework to incorporate complex chemistry into high-resolution smoothed particle hydrodynamics (SPH) simulations. Using the astrochemical package Krome, we model the evolution of chemistry along the dynamical history of particles from pre-existing simulations, focusing on gas and dust-phase reactions relevant to the formation and evolution of H − C − O bearing species, up to the formation of methanol (CH3OH). In this study we investigated the chemical complexity of circumstellar discs formed within a simulated star-forming cluster. By analyzing the vertical structure of these discs, we identify regions of enhanced chemical activity and explore the spatial distribution of complex organic molecules. Our results reveal that methanol, a key molecule to assess the possible chemical complexity in star-forming regions, is predominantly located within circumstellar discs in its gas-phase, particularly those surrounding older stellar objects. Unexpectedly, high concentrations of methanol were observed in regions of the disc where the physical conditions do not favor the formation of this molecule. This phenomenon is attributed to the accretion process, wherein low-temperature regions allow the formation of methanol on dust grains, which subsequently desorbs into the gas phase as material is accreted into the inner disc regions where temperatures exceed 104 K. This work sets a robust methodology for integrating complex chemistry into astrophysical simulations via post-processing techniques. By providing an up-to date chemical network that includes surface reactions, it offers a foundation for future studies aiming to investigate the chemical evolution of star-forming regions and circumstellar discs.
Description
Tesis presentada para optar al grado de Magíster en Astronomía
Keywords
Estrellas Formación, Dinámica molecular, Modelos astronómicos