000006160 001__ 6160
000006160 005__ 20230123211436.0
000006160 0247_ $$2DOI$$a 10.1051/0004-6361/202244148
000006160 037__ $$aSCART-2023-0085
000006160 100__ $$aAbdul-Masih, Michael  
000006160 245__ $$aConstraining the overcontact phase in massive binary evolution. II. Period stability of known O+O overcontact systems
000006160 260__ $$c2022
000006160 520__ $$aContext. Given that mergers are often invoked to explain many exotic phenomena in massive star evolution, understanding the evolutionary phase directly preceding a merger, the overcontact phase, is of crucial importance. Despite this, large uncertainties exist in our understanding of the evolution of massive overcontact binaries.  Aims: We aim to provide robust observational constraints on the future dynamical evolution of massive overcontact systems by measuring the rate at which the periods change for a sample of six such objects. Furthermore, we aim to investigate whether the periods of unequal-mass systems show higher rates of change than their equal mass counterparts, as theoretical models predict.  Methods: Using archival photometric data from various ground- and space-based missions covering up to ∼40 years, we measure the periods of each system over several smaller time spans. We then fit a linear regression through the measured periods to determine the rate at which the period is changing over the entire data set.  Results: We find that all of the stars in our sample have very small period changes and that there does not seem to be a correlation with the mass ratio. This implies that the orbital periods for these systems are stable on the nuclear timescale, and that the unequal-mass systems may not equalize as expected.  Conclusions: When comparing our results with population synthesis distributions, we find large discrepancies between the expected mass ratios and period stabilities. We find that these discrepancies can be mitigated to a degree by removing systems with shorter initial periods, suggesting that the observed sample of overcontact systems may originate from binary systems with longer initial orbital periods.
000006160 594__ $$aNO
000006160 6531_ $$abinaries: close
000006160 6531_ $$astars: massive
000006160 6531_ $$astars: evolution
000006160 6531_ $$atechniques: photometric
000006160 6531_ $$aAstrophysics - Solar and Stellar Astrophysics
000006160 700__ $$aEscorza, Ana  
000006160 700__ $$aMenon, Athira  
000006160 700__ $$aMahy, Laurent  
000006160 700__ $$aMarchant, Pablo
000006160 773__ $$c11$$nA18$$pAstronomy & Astrophysics$$v666$$y2022
000006160 8560_ $$flaurent.mahy@ksb-orb.be
000006160 8564_ $$s686474$$uhttp://publi2-as.oma.be/record/6160/files/Abdul-Masih_2022_aa44148-22.pdf
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000006160 905__ $$apublished in
000006160 980__ $$aREFERD