N2H+ kinematics in the g012.80 protocluster: Evidence for filament rotation and evolution.
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Date
2024
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
Nuestro principal objetivo es caracterizar la cinemática del gas denso a través de la molécula de N2H+ en el protocúmulo G012.80. Para complementar los datos de N2H+, empleamos observaciones de DCN, SiO, H41α, C18O y mapas de continuo. Todas las observaciones provienen del proyecto ALMA-IMF.
Analizamos múltiples componentes de velocidad mediante el ajuste hiperfino de N2H+, encontrando que dos componentes principales dominan la región. Estimamos gradientes de velocidad en dos de los filamentos principales (R1 y R2), los cuales trazan diferentes estructuras en diagramas posición-velocidad (PV). Utilizando los parámetros obtenidos del ajuste hiperfino de N2H+, estimamos la columna de densidad, las masas y los perfiles de masa. Los diagramas PV muestran estructuras en zigzag, enroscadas y helicoidales en el gas denso. En los dos filamentos principales, observamos diferencias significativas en las estructuras PV. En el filamento R1, se identifican estructuras helicoidales potencialmente asociadas con la rotación del filamento, además de una baja cantidad de cores. En contraste, R2 muestra estructuras oscilantes distribuidas en un rango de velocidad más estrecho, probablemente relacionadas con el colapso de cores masivos. En el f ilamento R1 identificamos un gradiente perpendicular asociado con una escala de tiempo de ∼0.1Myr, mientras que R2 no presenta gradientes de velocidad claros.
Los perfiles de masa en ambos filamentos se describen adecuadamente mediante las funciones λ(ω) = 5660(ω/pc)0.30 para R1 y λ(ω) = 6943(ω/pc)0.20 para R2. El filamento R2 tiene una tasa de formación estelar (SFR) de 55.3M⊙ Myr−1 y una eficiencia de formación estelar similar a la observada en el filamento ISF de Orión. Por otro lado, el filamento R1 solo contiene cores clasificados como prestelares, los cuales son menos masivos que los de R2. Considerando las diferencias cinemáticas, las tasas de formación estelar y los perfiles de masa en ambos filamentos, proponemos que R1 aún está rotando y representa una etapa más temprana de evolución, mientras que R2 ha colapsado más significativamente, alcanzando un estado más eficiente de formación estelar. Por tanto, G012 alberga f ilamentos masivos en diferentes etapas evolutivas.
We aim to characterize kinematic processes in the G012.80 protocluster (hereafter G012), also known as the W33 main clump. We principally use N2H+ (1−0) emission to trace the dense and cold gas in G012. Additionally, we reviewed complementary spectral lines including DCN, H41α, C18O, SiO, and continuum maps, all observations were provided by the ALMA-IMF Large Program. We perform a N2H+ hyperfine spectral line fitting to analyze multiple velocity components and extract spectral parameters. We estimated velocity gradients, column densities, and line-mass profiles for the two main filaments, R1 & R2, which show distinct position-velocity (PV) features. In the PV diagrams we observe zig-zag, twisting, and turning velocity structures pervasively in the dense gas. However, R1 exhibits a gradient feature of 10.4kms−1 pc−1, corresponding to an estimated timescale of 0.1Myr, potentially associated with filament rotation, as well as few cores above the completeness limit. In contrast, R2 exhibits compact velocity structures (∆V∼3kms−1), likely related to collapse, as evidenced by the presence of a comparatively large number of massive cores. Line-mass profiles follow λ(ω)=5660(ω/pc)0.30 for R1 and λ(ω)=6943(ω/pc)0.20 for R2, where ω is the projected radius in the plane-of-the-sky of the aligned f ilaments. R2 forms prestellar and protostellar cores at a star formation rate of SFR=55.3M⊙Myr−1, with efficiency similar to Orion ISF. In contrast, the R1 filament, which lacks protostellar cores, only contains a few cores in the prestellar phase, resulting in an SFR of 4.24M⊙ Myr−1. Considering the dense gas kinematic, core formation, and line-mass profiles difference, we propose that R1 is still rotating and younger than the R2 filament, which has evolved further, toward collapse, to a higher star formation rate. G012 thus contains massive filaments in different evolutionary stages.
We aim to characterize kinematic processes in the G012.80 protocluster (hereafter G012), also known as the W33 main clump. We principally use N2H+ (1−0) emission to trace the dense and cold gas in G012. Additionally, we reviewed complementary spectral lines including DCN, H41α, C18O, SiO, and continuum maps, all observations were provided by the ALMA-IMF Large Program. We perform a N2H+ hyperfine spectral line fitting to analyze multiple velocity components and extract spectral parameters. We estimated velocity gradients, column densities, and line-mass profiles for the two main filaments, R1 & R2, which show distinct position-velocity (PV) features. In the PV diagrams we observe zig-zag, twisting, and turning velocity structures pervasively in the dense gas. However, R1 exhibits a gradient feature of 10.4kms−1 pc−1, corresponding to an estimated timescale of 0.1Myr, potentially associated with filament rotation, as well as few cores above the completeness limit. In contrast, R2 exhibits compact velocity structures (∆V∼3kms−1), likely related to collapse, as evidenced by the presence of a comparatively large number of massive cores. Line-mass profiles follow λ(ω)=5660(ω/pc)0.30 for R1 and λ(ω)=6943(ω/pc)0.20 for R2, where ω is the projected radius in the plane-of-the-sky of the aligned f ilaments. R2 forms prestellar and protostellar cores at a star formation rate of SFR=55.3M⊙Myr−1, with efficiency similar to Orion ISF. In contrast, the R1 filament, which lacks protostellar cores, only contains a few cores in the prestellar phase, resulting in an SFR of 4.24M⊙ Myr−1. Considering the dense gas kinematic, core formation, and line-mass profiles difference, we propose that R1 is still rotating and younger than the R2 filament, which has evolved further, toward collapse, to a higher star formation rate. G012 thus contains massive filaments in different evolutionary stages.
Description
Tesis presentada para optar al grado académico de Magíster en Astronomía
Keywords
Astrodinámica, Estrellas Cúmulos, Nubes moleculares