Austrian Early Career Conference 2024

Contribution:
Poster

Authors:
Sepideh Abdollahihashjin; Ylva Götberg

Affiliations:
Institute of Science and Technology Austria (ISTA)

Title:
The dependence of orbital period on the mass of stars stripped in binaries

Abstract:
Around one-third of massive stars are expected to lose their hydrogen-rich envelopes due to interaction with another star in a binary system. Most of the resulting "stripped stars" are expected to have masses predictable from the star's initial mass and the orbital period of the binary system. We explored the dependence of these two factors on the mass of the stripped star produced through mass transfer.
We used the MESA binary stellar evolution code to model a 12 solar masses star orbiting an 8.6 solar masses companion star on a twenty-day orbit. In this simulation, the most massive star in the system fills its Roche lobe, and mass transfer initiates. We focused on mass transfer during the main sequence when the helium core is not defined, and after the main sequence and during the Hertzsprung gap, when the helium core contracts towards central helium ignition. We chose these evolutionary phases prior to the long-lasting central helium burning as they produce long-lived stripped stars.
We found mass transfer initiates during a 12 solar masses star's main sequence creating lower-mass stripped stars if the orbital period is between 0.9 and 5.3 days. Longer orbital periods (up to 1600 days) produce similar-mass stripped stars as the mass transfer happens after the main sequence when the helium core is defined. Our next step is to model binary systems with a range of periods to help inform the stripped star mass distribution and binary properties in population synthesis codes.