---
OA_place: publisher
OA_type: diamond
_id: '18852'
abstract:
- lang: eng
  text: 'Recent observations have found a growing number of hypervelocity stars with
    speeds of ≈1500 − 2500 km s−1 that could have only been produced through thermonuclear
    supernovae in white dwarf binaries. Most of the observed hypervelocity runaways
    in this class display a surprising inflated structure: their current radii are
    roughly an order of magnitude greater than they would have been as white dwarfs
    filling their Roche lobe. While many simulations exist studying the dynamical
    phase leading to supernova detonation in these systems, no detailed calculations
    of the long-term structure of the runaways have yet been performed. We used an
    existing AREPO hydrodynamical simulation of a supernova in a white dwarf binary
    as a starting point for the evolution of these stars with the one-dimensional
    stellar evolution code MESA. We show that the supernova shock is not energetic
    enough to inflate the white dwarf over timescales longer than a few thousand years,
    significantly shorter than the 105 − 6 year lifetimes inferred for observed hypervelocity
    runaways. Although they experience a shock from a supernova less than ≈0.02 R⊙
    away, our models do not experience significant interior heating, and all contract
    back to radii of around 0.01 R⊙ within about 104 years. Explaining the observed
    inflated states requires either an additional source of significant heating or
    some other physics that is not yet accounted for in the subsequent evolution.'
acknowledgement: 'This project was originally started as part of the Kavli Summer
  Program which took place in the Max Planck Institute for Astrophysics in Garching
  in July 2023, supported by the Kavli Foundation. We are grateful to Stephen Justham,
  Selma de Mink, and Jim Fuller for enriching discussions. We would like to thank
  the anonymous referee for their helpful report. A.B. was supported by the Deutsche
  Forschungsgemeinschaft (DFG) through grant GE2506/18-1. K.J.S. was supported by
  NASA through the Astrophysics Theory Program (80NSSC20K0544) and by NASA/ESA Hubble
  Space Telescope programs #15871 and #15918. W.E.K. was supported by NSF Grants OAC-2311323,
  AST-2206523, and NASA/ESA HST-AR-Theory HSTAR-16613.002-A. K.E. was supported in
  part by HST-GO-17441.001-A. AB and ASR would like to thank Rob Farmer for his support
  with PyMESA.'
article_number: A114
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Aakash
  full_name: Bhat, Aakash
  last_name: Bhat
- first_name: Evan B.
  full_name: Bauer, Evan B.
  last_name: Bauer
- first_name: Rüdiger
  full_name: Pakmor, Rüdiger
  last_name: Pakmor
- first_name: Ken J.
  full_name: Shen, Ken J.
  last_name: Shen
- first_name: Ilaria
  full_name: Caiazzo, Ilaria
  id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d
  last_name: Caiazzo
  orcid: 0000-0002-4770-5388
- first_name: Abinaya Swaruba
  full_name: Rajamuthukumar, Abinaya Swaruba
  last_name: Rajamuthukumar
- first_name: Kareem
  full_name: El-Badry, Kareem
  last_name: El-Badry
- first_name: Wolfgang E.
  full_name: Kerzendorf, Wolfgang E.
  last_name: Kerzendorf
citation:
  ama: Bhat A, Bauer EB, Pakmor R, et al. Supernova shocks cannot explain the inflated
    state of hypervelocity runaways from white dwarf binaries. <i>Astronomy &#38;
    Astrophysics</i>. 2025;693(1). doi:<a href="https://doi.org/10.1051/0004-6361/202451371">10.1051/0004-6361/202451371</a>
  apa: Bhat, A., Bauer, E. B., Pakmor, R., Shen, K. J., Caiazzo, I., Rajamuthukumar,
    A. S., … Kerzendorf, W. E. (2025). Supernova shocks cannot explain the inflated
    state of hypervelocity runaways from white dwarf binaries. <i>Astronomy &#38;
    Astrophysics</i>. EDP Sciences. <a href="https://doi.org/10.1051/0004-6361/202451371">https://doi.org/10.1051/0004-6361/202451371</a>
  chicago: Bhat, Aakash, Evan B. Bauer, Rüdiger Pakmor, Ken J. Shen, Ilaria Caiazzo,
    Abinaya Swaruba Rajamuthukumar, Kareem El-Badry, and Wolfgang E. Kerzendorf. “Supernova
    Shocks Cannot Explain the Inflated State of Hypervelocity Runaways from White
    Dwarf Binaries.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2025. <a href="https://doi.org/10.1051/0004-6361/202451371">https://doi.org/10.1051/0004-6361/202451371</a>.
  ieee: A. Bhat <i>et al.</i>, “Supernova shocks cannot explain the inflated state
    of hypervelocity runaways from white dwarf binaries,” <i>Astronomy &#38; Astrophysics</i>,
    vol. 693, no. 1. EDP Sciences, 2025.
  ista: Bhat A, Bauer EB, Pakmor R, Shen KJ, Caiazzo I, Rajamuthukumar AS, El-Badry
    K, Kerzendorf WE. 2025. Supernova shocks cannot explain the inflated state of
    hypervelocity runaways from white dwarf binaries. Astronomy &#38; Astrophysics.
    693(1), A114.
  mla: Bhat, Aakash, et al. “Supernova Shocks Cannot Explain the Inflated State of
    Hypervelocity Runaways from White Dwarf Binaries.” <i>Astronomy &#38; Astrophysics</i>,
    vol. 693, no. 1, A114, EDP Sciences, 2025, doi:<a href="https://doi.org/10.1051/0004-6361/202451371">10.1051/0004-6361/202451371</a>.
  short: A. Bhat, E.B. Bauer, R. Pakmor, K.J. Shen, I. Caiazzo, A.S. Rajamuthukumar,
    K. El-Badry, W.E. Kerzendorf, Astronomy &#38; Astrophysics 693 (2025).
date_created: 2025-01-19T23:01:51Z
date_published: 2025-01-07T00:00:00Z
date_updated: 2026-02-16T12:08:05Z
day: '07'
ddc:
- '520'
department:
- _id: IlCa
doi: 10.1051/0004-6361/202451371
external_id:
  arxiv:
  - '2407.03424'
  isi:
  - '001406577300001'
file:
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  date_created: 2025-01-20T09:57:00Z
  date_updated: 2025-01-20T09:57:00Z
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file_date_updated: 2025-01-20T09:57:00Z
has_accepted_license: '1'
intvolume: '       693'
isi: 1
issue: '1'
language:
- iso: eng
license: https://creativecommons.org/licenses/by/4.0/
month: '01'
oa: 1
oa_version: Published Version
publication: Astronomy & Astrophysics
publication_identifier:
  eissn:
  - 1432-0746
  issn:
  - 0004-6361
publication_status: published
publisher: EDP Sciences
quality_controlled: '1'
scopus_import: '1'
status: public
title: Supernova shocks cannot explain the inflated state of hypervelocity runaways
  from white dwarf binaries
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 693
year: '2025'
...