Mass-luminosity anomalies: evidence of recent stellar interaction in the extraordinary blue straggler S1082?
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Date
2025
Authors
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Publisher
Universidad de Concepción
Abstract
Presento un estudio observacional y teórico del complejo sistema estelar S1082 en el cúmulo abierto M67. Este sistema está formado por al menos cuatro estrellas: una estrella "blue straggler" en una binaria eclipsante de 1,07 días con una estrella de secuencia principal (Binaria A), y otra estrella "blue straggler" en una órbita de 1185 días con una compañera desconocida (Binaria B). Analizé los datos observacionales para obtener los parámetros orbitales y estelares de los componentes del sistema eclipsante. A continuación, exploré escenarios de transferencia de masa y encuentros dinámicos que pudieran explicar las propiedades derivadas de todos los componentes de S1082. Combiné fotometría de alta precisión de K2 y TESS con curvas de luz de archivo, nuevas mediciones de velocidad radial, e imágenes de speckle para refinar los parámetros orbitales y físicos del sistema. Para explorar las vías de formación, realizé simulaciones de evolución binaria con MESA y experimentos de dispersión dinámica con FEWBODY, seguidos de modelos de evolución de mareas. Las soluciones de velocidad radial arrojan masas dinámicas significativamente distintas para la binaria A, con la masa de la estrella secundaria ahora consistente con la masa de "turn-off" del cúmulo. Las imágenes de speckle muestran dos componentes resueltos separados por 390 UA en proyección; en combinación con las dos órbitas espectroscópicas, esto sugiere una configuración cuádruple jerárquica. Concluimos que S1082 A se formó muy probablemente a través de un intercambio dinámico en el que participaron una binaria consistente de una "blue straggler" y una enana blanca, y una intrusa estrella de secuencia principal, seguido de una circularización por mareas. Si A y B están unidos gravitacionalmente, es probable que su emparejamiento se produjera tras su formación independiente, a través de un encuentro dinámico posterior. Este trabajo subraya la importancia de la dinámica estelar en la configuración de la evolución de sistemas estelares complejos dentro de entornos de cúmulos como M67.
I present an observational and theoretical study of the complex stellar system S1082 in the open cluster M67. This system consists of at least four stars: a blue straggler in a 1.07-day eclipsing binary with a main sequence star (Binary A), and another blue straggler in a 1185-day orbit with an unknown companion (Binary B). I analyzed observational data to obtain the orbital and stellar parameters of the components of the eclipsing system. I then explored mass transfer and dynamical encounter scenarios that could explain the derived properties of all of the components of S1082. I combined high-precision photometry from K2 and TESS with archival light curves, new radial-velocity measurements, and speckle imaging to refine the orbital and physical parameters of the system. To explore formation pathways, I conducted binary evolution simulations with MESA and dynamical scattering experiments with FEWBODY, followed by tidal evolution modeling. My revised radial-velocity solutions yield significantly changed dynamical masses for Binary A, with the secondary mass now consistent with the cluster turnoff mass. Speckle imaging shows two resolved components separated by 390 AU in projection; in combination with the two spectroscopic orbits, this is suggestive of a hierarchical quadruple configuration. I conclude that S1082 A most plausibly formed through a dynamical exchange involving a BSS–WD binary and a MS intruder, followed by tidal circularization. If A and B are gravitationally bound, their pairing likely occurred after their independent formation, through a subsequent dynamical encounter. This work underscores the importance of stellar dynamics in shaping the evolution of complex stellar systems within cluster environments such as M67.
I present an observational and theoretical study of the complex stellar system S1082 in the open cluster M67. This system consists of at least four stars: a blue straggler in a 1.07-day eclipsing binary with a main sequence star (Binary A), and another blue straggler in a 1185-day orbit with an unknown companion (Binary B). I analyzed observational data to obtain the orbital and stellar parameters of the components of the eclipsing system. I then explored mass transfer and dynamical encounter scenarios that could explain the derived properties of all of the components of S1082. I combined high-precision photometry from K2 and TESS with archival light curves, new radial-velocity measurements, and speckle imaging to refine the orbital and physical parameters of the system. To explore formation pathways, I conducted binary evolution simulations with MESA and dynamical scattering experiments with FEWBODY, followed by tidal evolution modeling. My revised radial-velocity solutions yield significantly changed dynamical masses for Binary A, with the secondary mass now consistent with the cluster turnoff mass. Speckle imaging shows two resolved components separated by 390 AU in projection; in combination with the two spectroscopic orbits, this is suggestive of a hierarchical quadruple configuration. I conclude that S1082 A most plausibly formed through a dynamical exchange involving a BSS–WD binary and a MS intruder, followed by tidal circularization. If A and B are gravitationally bound, their pairing likely occurred after their independent formation, through a subsequent dynamical encounter. This work underscores the importance of stellar dynamics in shaping the evolution of complex stellar systems within cluster environments such as M67.
Description
Tesis presentada para optar al grado de Magíster en Astronomía.
Keywords
Astronomy, Stellar system S1082, Open cluster M67