From Main Sequence Binary to Blast: MESA Modeling of the Double-Detonation Progenitor PTF1~J2238+7430

TL;DR

This study uses detailed MESA binary evolution simulations to model the formation of a specific sdB+WD system, PTF1 J2238+7430, as a potential double-detonation supernova progenitor.

Contribution

It demonstrates how binary evolution parameters can reproduce the observed properties of PTF1 J2238+7430 and constrains initial conditions leading to such progenitors.

Findings

Models match the observed 0.406 M_sun sdB and 0.72 M_sun WD in a 76.34-minute orbit.

High CE ejection efficiency is required to reproduce the system.

Initial binary parameters are constrained to a specific range for double-detonation progenitors.

Abstract

Hot subdwarf B (sdB) stars in close binaries with white dwarf (WD) companions are potential progenitors of double-detonation thermonuclear supernovae. The recently discovered system PTF1 J2238+7430 is a candidate for this evolutionary channel, hosting a low-mass sdB and a comparatively massive WD in a compact orbit. We aim to reproduce the evolutionary history of PTF1 J2238+7430, in which the sdB forms first via stable mass transfer, followed by the formation of the WD through a subsequent common-envelope (CE) phase. Additionally, we seek to constrain the range of initial binary parameters that can lead to such double-detonation progenitors. Using the Modules for Experiments in Stellar Astrophysics (MESA), we performed detailed binary evolution simulations from the zero-age main sequence to the present-day configuration. We explored initial stellar masses, orbital periods, and mass-loss fractions, including the effects of angular momentum transfer, tidal synchronization, and gravitational-wave-driven orbital evolution. The post-CE binary properties were derived using the standard energy formalism. Our models successfully reproduce the observed properties of PTF1 J2238+7430, consisting of a 0.406 solar-mass sdB and a 0.72 solar-mass WD in a 76.34-minute orbit. Stable Roche-lobe overflow of an approximately 2.7 solar-mass donor produces the sdB, while the WD forms from the initially less massive companion during an episode of CE evolution. We find that the CE ejection efficiency must be high to match the observed orbit, exceeding canonical values for similar systems. We further delineate the allowed parameter space for initial binaries that can evolve into sdB+WD systems consistent with double-detonation progenitors. These limits are preliminary; a systematic exploration of all parameters is needed for robust constraints, but our results provide a useful starting point for future work.