A Not-So-Compact Companion: Massive, Oversize White Dwarf in a Post-Common Envelope Eclipsing Binary

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Hauptverfasser: Motherway, Erin M., Linck, Evan, Mathieu, Robert D., Dixon, Don, Stassun, Keivan G., Breivik, Katelyn, Majewski, Steven R., Pols, Onno
Format: Preprint
Veröffentlicht: 2026
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author Motherway, Erin M.
Linck, Evan
Mathieu, Robert D.
Dixon, Don
Stassun, Keivan G.
Breivik, Katelyn
Majewski, Steven R.
Pols, Onno
author_facet Motherway, Erin M.
Linck, Evan
Mathieu, Robert D.
Dixon, Don
Stassun, Keivan G.
Breivik, Katelyn
Majewski, Steven R.
Pols, Onno
contents We provide a detailed characterization of 2M07515777+1807352, a post-common envelope eclipsing binary system with a 10.3 d, nearly, but not quite, circular orbit (e = 0.02). This system consists of a massive white dwarf (WD) ($1.08$ M$_{\odot}$) and a 4400 K main-sequence companion (0.66 M$_{\odot}$). This WD is among the most massive known within post-common envelope binary systems. We also find, through both spectral energy distribution and $\it{TESS}$ light curve analyses, that the WD has a radius of $1.54\pm 0.07 R_{\oplus}$, roughly $12σ$ larger than the expected value from WD mass-radius relationships. Both the Lomb-Scargle analysis and the $v \sin{i}$ of the system indicate the main-sequence companion to be super-synchronously rotating at a period of $\sim$6 days, which may suggest accretion occurred during the evolution of the system. This binary also shares similar physical characteristics with six other post-common envelope systems hosting massive WDs, which may point to a shared formation pathway. We model the history of this system with COSMIC and find that it likely formed through an episode of common envelope evolution following the onset of mass transfer when the progenitor primary was on either the early or the thermally pulsing stages of the asymptotic giant branch. As a result of its properties, the study of 2M07515777+1807352 can provide new insights regarding many key outstanding questions in our understanding of common envelope evolution.
format Preprint
id arxiv_https___arxiv_org_abs_2601_14378
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Not-So-Compact Companion: Massive, Oversize White Dwarf in a Post-Common Envelope Eclipsing Binary
Motherway, Erin M.
Linck, Evan
Mathieu, Robert D.
Dixon, Don
Stassun, Keivan G.
Breivik, Katelyn
Majewski, Steven R.
Pols, Onno
Solar and Stellar Astrophysics
We provide a detailed characterization of 2M07515777+1807352, a post-common envelope eclipsing binary system with a 10.3 d, nearly, but not quite, circular orbit (e = 0.02). This system consists of a massive white dwarf (WD) ($1.08$ M$_{\odot}$) and a 4400 K main-sequence companion (0.66 M$_{\odot}$). This WD is among the most massive known within post-common envelope binary systems. We also find, through both spectral energy distribution and $\it{TESS}$ light curve analyses, that the WD has a radius of $1.54\pm 0.07 R_{\oplus}$, roughly $12σ$ larger than the expected value from WD mass-radius relationships. Both the Lomb-Scargle analysis and the $v \sin{i}$ of the system indicate the main-sequence companion to be super-synchronously rotating at a period of $\sim$6 days, which may suggest accretion occurred during the evolution of the system. This binary also shares similar physical characteristics with six other post-common envelope systems hosting massive WDs, which may point to a shared formation pathway. We model the history of this system with COSMIC and find that it likely formed through an episode of common envelope evolution following the onset of mass transfer when the progenitor primary was on either the early or the thermally pulsing stages of the asymptotic giant branch. As a result of its properties, the study of 2M07515777+1807352 can provide new insights regarding many key outstanding questions in our understanding of common envelope evolution.
title A Not-So-Compact Companion: Massive, Oversize White Dwarf in a Post-Common Envelope Eclipsing Binary
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2601.14378