Evidence from stellar rotation of enhanced disc dispersal - I. The case of the triple visual system BD−21 1074 in the β Pictoris association

摘要: Context. The early stage of stellar evolution is characterized by a magnetic coupling between star and its accretion disc, known as star-disc locking mechanism. disc-locking prevents the to spin rotation up, timescale depends on disc lifetime, which should not be longer than about 10 Myr. Some mechanisms can significantly shorten this allowing few stars start spinning up much earlier other increasing observed period dispersion among coeval stars. Aims. In present study, we aim investigate how properties circumstellar environment more specifically presence close companion. Methods. We have identified multiple systems, composed with similar masses, belong associations age. Since all parameters that are responsible for rotational evolution, exception initial rotation, components, expect significant differences periods only arise from in lifetimes. A photometric timeseries allowed us measure each component, while high-resolution spectra provided fundamental parameters, vsini chromospheric line fluxes. Results. collected photometry BD−211074, member 21 Myr old β Pictoris association, measured brightest components B. They differ significantly, component B, has closer companion C, rotates faster distant isolated A. It also displays slightly higher activity level. Conclusions. B mass, age, chemical composition, ascribe difference either different or phases arising C. specific case second scenario seems favored. However, statistically meaningful sample yet needed able infer likely. our hypothesis phase, any planet orbiting star, if found future investigations, likely formed very rapidly owing gravitational instability mechanism, rather core accretion. Only large alone could account difference, leaving comparable