Facultad de Ciencias Físicas y Matemáticas
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Browsing Facultad de Ciencias Físicas y Matemáticas by Subject "Acrecencia (astrofísica)"
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Item Understanding the impact of binary mass transfer in the accretor’s measurable parameters.(Universidad de Concepción, 2025) Vilaxa Campos, Magdalena Andrea; Leigh, Nathan W. C.Stars in binaries and higher order systems can experience mass transfer events between their components. The angular momentum carried by the mass gained by the accretor can change the observable parameters of the star and spin it up to critical rotation. In the case of disk accretion, a mass gain lesser than a 10% of the accretor’s initial mass is expected to bring it to a critical rotation rate and break it apart. In this work, we aim to explore the spin-up effect of direct accretion through a stream as a possible mechanism for an accretor to gain more than a tenth of its mass without gaining enough momentum to reach critical rotation. Here, we present a novel analytical model to characterize the effects of direct mass transfer in the accretor’s measurable parameters as a function of the binary’s semi-major axis and eccentricity and the donor’s rotational velocity. This model takes a two-body approach to the problem, where a stream is decomposed as many discrete particles that do not interact with each other and are influenced by only the accretor’s gravitational potential. Each parcel has an instant orbital solution derived from its initial conditions. The contribution each accreted parcel has to the total spin-up of the accretor is given by its tangential velocity at impact, through conservation of angular momentum. We find that direct mass transfer proves to be less efficient at spinning up the accretor than an accretion disk and thus enables the star to gain a greater fraction (>10%) of its initial mass without reaching critical rotation. In addition, we quantify the fraction of mass that directly impact the accretor in contrast to the mass that is either lost from the system or creates a disk around the star.