dorsal/arxiv
View SchemaIK Pegasi and the Double Merger Path to Type Ia Supernovae
| Authors | Na'ama Hallakoun, Sahar Shahaf, Sagi Ben-Ami, Oren Ironi, Param Rekhi, Hans-Walter Rix |
|---|---|
| Categories | |
| ArXiv ID | 2601.08903vv1 |
| URL | https://arxiv.org/abs/2601.08903 |
| License | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ |
Abstract
Recent Gaia astrometry has revealed thousands of main-sequence + white-dwarf binaries (MS+WD) at separations of ~0.1-10 au, including a subset hosting unusually massive (>~0.8 Msun) WDs. We argue that s-process enrichment in the non-degenerate companion provides a powerful diagnostic for identifying WDs that formed via mergers in hierarchical triple systems. For a massive WD, standard single-star evolution requires a massive (>~4 Msun) progenitor, yet such progenitors produce negligible s-process yields. We define IK Peg-type systems as those exhibiting this mass-yield tension: barium-enhanced companions orbiting WDs too massive to have descended from efficient s-process producers. The well-known system IK Peg exemplifies this class. Applying this framework to published spectroscopic data reveals several additional candidates, and we estimate that a few dozen such systems should exist in the current Gaia sample. If these systems trace inner-binary mergers in primordial triples, they represent observable intermediate stages towards eventual Type Ia supernovae via the double-merger pathway, as predicted by recent population-synthesis models.
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"abstract": "Recent Gaia astrometry has revealed thousands of main-sequence + white-dwarf binaries (MS+WD) at separations of ~0.1-10 au, including a subset hosting unusually massive (\u003e~0.8 Msun) WDs. We argue that s-process enrichment in the non-degenerate companion provides a powerful diagnostic for identifying WDs that formed via mergers in hierarchical triple systems. For a massive WD, standard single-star evolution requires a massive (\u003e~4 Msun) progenitor, yet such progenitors produce negligible s-process yields. We define IK Peg-type systems as those exhibiting this mass-yield tension: barium-enhanced companions orbiting WDs too massive to have descended from efficient s-process producers. The well-known system IK Peg exemplifies this class. Applying this framework to published spectroscopic data reveals several additional candidates, and we estimate that a few dozen such systems should exist in the current Gaia sample. If these systems trace inner-binary mergers in primordial triples, they represent observable intermediate stages towards eventual Type Ia supernovae via the double-merger pathway, as predicted by recent population-synthesis models.",
"arxiv_id": "2601.08903",
"authors": [
"Na\u0027ama Hallakoun",
"Sahar Shahaf",
"Sagi Ben-Ami",
"Oren Ironi",
"Param Rekhi",
"Hans-Walter Rix"
],
"categories": [
"astro-ph.SR",
"astro-ph.HE"
],
"license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
"title": "IK Pegasi and the Double Merger Path to Type Ia Supernovae",
"url": "https://arxiv.org/abs/2601.08903",
"version": "v1"
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