Evolved stars, multiplicity and planets: Shaping and Being Shaped by Stellar Evolution

summary

The gist

The gist: Understanding how planets and stellar companions survive and interact with their host stars as they evolve, or are ultimately destroyed in the process, is essential both for predicting the

In short

The paper explores how planets and stellar companions interact with evolving stars, which is crucial for understanding planetary system futures and galactic chemical evolution. Observations show that companions significantly affect stellar winds and orbital evolution during giant phases. ALMA2040 will revolutionize this field by detecting accreting companions and engulfment signatures in hundreds of evolved systems.

Key concepts

Stellar Multiplicity: This refers to a star system having more than one star, such as a binary or multiple system. The paper focuses on how the presence of these companions influences the life and death processes of the host stars, leading to various observed stellar outcomes.
Mass Transfer Regimes: This describes different ways mass can move between stars in a binary system as they evolve. These regimes depend on whether the companion's gravitational influence is strong enough to capture wind material (Bondi-Hoyle-Lyttleton) or if the star's outer layers fill its gravitational sphere (Roche Lobe Overflow).
Post-Interaction Systems: These are complex stellar remnants, like dusty post-AGB binaries or merger products, formed after strong binary interactions. These systems are difficult to study because they often lack optical counterparts and require infrared observations to understand their evolutionary paths.
Planetary Engulfment: This is the process where a planet orbiting too closely around an evolving star gets swallowed by the star as it expands into a giant. The paper notes that this dynamical effect has been observed in nearby AGB stars, providing a key area for future ALMA studies.

Terminology used across episodes

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Sample Complexity — explained in 20 episodes
Retrieval-Augmented Generation (RAG) — explained in 19 episodes
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Flow Matching — explained in 17 episodes
Quantum Fisher Information (QFI) — explained in 17 episodes

This episode discusses

The paper

Evolved stars, multiplicity and planets: Shaping and Being Shaped by Stellar Evolution · Read on arXiv

Theo Khouri, Wouter Vlemmings, Elvire De Beck, Tomek Kaminski, §ıssa Danilovich, §Marie Van de Sande, Devika Kamath, §Maksym Mohorian, Shazrene Mohamed, Alain Baudry, Raghvendra Sahai, Carmen Sanchez-Contreras §, Javier Alcolea, Luis Velilla-Prieto §, Lea Planquart §, Leen Decin, ř Pierre Kervella, Bannawit Pimpanuwat, Matthias Maercker, Sandra Etoka, Behzad Bojnordi Arbab, Ramlal Unnikrishnan 8, Guillermo Quintana-Lacaci §, Miguel Santander-Garcóa 12

Department of Physics and Astronomy, Chalmers University of Technology · Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences · University of Newcastle · Anton Pannekoek Institute for Astronomy, University of Amsterdam · School of Physics, University College Dublin · School of Mathematical and Physical Sciences, Macquarie University · Department of Astronomy, University of Virginia 7 and Virginia Institute for Theoretical Astronomy at the University of Virginia 89 Univ. Bordeaux L.A.B. · Jet Propulsion Laboratory, California Institute of Technology 10 · Centro de Astrobiologia (CAB), CSIC/INTA Spain 11 · Observatorio Astronomico Nacional IGN/GNIG MITMS Spain 12 · Institute of Fundamental Physics (IFF) CSIC Spain 13 · KU Leuven Belgium 14 · LIRA Observatoire de Paris Universite PSL Sorbonne Université Universite Paris Cité CY Cergy Paris Université e · French-Chilean Laboratory for Astronomy IRL 3386 CNRS and U. de Chile Casilla 36-D Santiago Chile · National Astronomical Research Institute of Thailand Public Organization Chiang Mai Thailand 17 · Jodrell Bank Centre for Astrophysics The University of Manchester UK 18

Understanding how planets and stellar companions survive and interact with their host stars as they evolve, or are ultimately destroyed in the process, is essential both for predicting the long-term future of planetary systems like our own and the contribution of stars to galactic chemical evolution. In this white paper, we discuss how the next generation ALMA (ALMA2040) will revolutionize our understanding of the key processes by detecting and characterising accreting companions and planetary engulfment signatures in hundreds of systems with evolved stars.

Transcript

Introduction to the show: ident: Astrophysics Radio. Generated commentary on the latest astrophysics papers.

Vera: We're looking at the paper: "Evolved stars, multiplicity and planets".

Jocelyn: The gist: Understanding how planets and stellar companions survive and interact with their host stars as they evolve, or are ultimately destroyed in the process,

Vera: First, who's behind it and why it matters.

Paper summary: Vera: So to recap this paper on "Evolved stars, multiplicity and planets: Shaping and Being Shaped by Stellar Evolution," they are focusing on how companions influence stars as they evolve or get destroyed.

Jocelyn: The central thesis is that the effects of stellar and planetary companions on the wind of evolved stars are everywhere, even for stars that shouldn't have interacted with anything before.

Subrahmanyan: This means we need to account for spectacular events like mergers and envelope ejections, or less dramatic things like enhanced mass loss.

Vera: The paper covers the wide range of progeny from these interactions, including sub-dwarf B stars and white dwarf systems.

Jocelyn: It also tackles the orbital evolution problem, noting that current theory struggles to explain the distribution of distances and eccentricities we see in these binary interaction products.

Subrahmanyan: The authors suggest several ways to fix this tension, like refining mass transfer physics or considering circumbinary discs.

Vera: And they detail the different mass transfer regimes—Bondi-Hoyle-Lyttleton versus Wind Roche Lobe Overflow—to show how accretion efficiency changes based on separation.

Jocelyn: They also look at the end products, like post-AGB binaries and transients, and discuss the formation of circumbinary discs around these systems.

Subrahmanyan: The paper suggests these discs might be important nurseries for second-generation giant planets, even if fragmentation seems improbable right now.

Vera: And finally, they look at planetary engulfment as a potential fate for planets in close orbits as stars swell up on the giant branches.

Conclusion: Vera: Looking at this work by Khouri et al., Vlemmings et al., De Beck et al., Kaminski, Danilovich, Van de Sande, Kamath, Mohorian, Mohamed, Baudry, Sahai, Sanchez-Contreras and Alcolea. It really ties together how stellar evolution and planetary systems are intertwined.

Jocelyn: The implications are that we need better observational tools to detect these subtle interactions in evolved stars using ALMA2040 to map out these complex outcomes.

Subrahmanyan: From a cosmological standpoint, it suggests that the processes shaping these stars have a direct link to how we understand the history of star and planet formation across cosmic time.

Vera: It’s about recognizing that our current models for stellar evolution might be incomplete because they don't fully account for these companion effects in evolved phases.

Jocelyn: The real takeaway is that observing these systems with ALMA will give us the data needed to see exactly what happens when stars get big and complex.

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