Tracing chemical depletion in evolved binaries hosting second-generation transition discs
Maksym Mohorian1,2, Devika Kamath1,2,3, Meghna Menon1,2
1School of Mathematical and Physical Sciences, Macquarie University, Balaclava Road, Sydney, NSW 2109, Australia.
Monthly Notices of the Royal Astronomical Society
|March 19, 2025
Summary
Chemical depletion is significantly higher in binary stars with transition discs compared to others. These post-AGB/post-RGB stars show depletion patterns similar to the interstellar medium, offering insights into circumbinary disc chemistry.
Area of Science:
- Astrophysics
- Stellar Evolution
- Astrochemistry
Background:
- Chemical depletion mechanisms in astrophysical environments remain poorly understood.
- Post-asymptotic giant branch (post-AGB) and post-red giant branch (post-RGB) stars with transition discs offer unique laboratories to study these processes.
Purpose of the Study:
- Investigate chemical depletion in post-AGB/post-RGB binary stars with transition discs.
- Compare depletion efficiencies and patterns with other stellar populations and the interstellar medium.
Main Methods:
- High-resolution optical spectroscopy using HERMES/Mercator and UVES/VLT.
- Detailed chemical abundance analysis (1D LTE and 1D NLTE corrections) for elements C to Eu.
- Analysis of correlations between abundances and binary system parameters.
Main Results:
- Depletion efficiency, indicated by [S/Ti], is higher in post-AGB/post-RGB binaries with transition discs.
- Depletion is significantly stronger in these systems than in young stars with transition discs.
- [X/Zn] abundance ratios for volatile and refractory elements generally resemble interstellar medium trends.
Conclusions:
- Post-AGB/post-RGB binaries with transition discs exhibit enhanced chemical depletion.
- Depletion patterns provide indirect constraints on depletion mechanisms within circumbinary discs.
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