---
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
_id: '21745'
abstract:
- lang: eng
  text: 'The small DAHe and DAe spectral classes comprise isolated, hydrogen-dominated
    atmosphere white dwarfs that exhibit variable photometric flux and Balmer line
    emission. These mysterious systems offer unique insight into the complex interplay
    between magnetic fields, stellar rotation and atmospheric activity in single white
    dwarfs. DAHe stars have detectable magnetic fields through Zeeman-split spectral
    lines, whereas DAe stars lack such splitting. We report the first discovery and
    characterization of magnetism in the DAe white dwarf WD J165335.21−100116.33 with
    new time-resolved spectropolarimetry from FORS2. We detect a weak but variable
    longitudinal magnetic field with values Bz > −9.2 ± 2.4 kG and Bz < −2.2 ± 1.0
    kG. Independent ZTF and ATLAS photometry reveal a consistent period of P = 80.3070
    ± 0.0007 h. Time-resolved optical spectroscopy obtained with six ground-based
    instruments demonstrates strong modulation in the strength of the Hα and Hβ Balmer
    line emission with P = 80.2922 ± 0.0108 h. The photometric flux and Balmer emission
    strength vary in antiphase, with the strongest magnetic detections coinciding
    with phases of low photometric flux and strong line emission. These characteristicssupport
    the theory that a magnetically active, temperature-inverted spot/region is producing
    an optically thin chromospheric emission region. Comparison with other DAe and
    DAHe white dwarfsreveals all systems have a strikingly similar antiphase phenomenology,
    reinforcing the theory that they are subject to a unified physical mechanism.
    With the detection of a weak magnetic field, we reclassify WD J165335.21−100116.33
    as a low-field DAHe white dwarf. '
acknowledgement: "This project has received funding from the European Research Council
  under the European Union’s Horizon 2020 research and innovation programme (Grant
  agreement numbers 101002408). The observationsfrom the FOcal Reducer/low dispersion
  Spectrograph 2 (FORS2) instrument were collected at the European Southern Observatory
  (ESO) under ESO programme(s) 113.26ES.001. This work has made use of data from the
  European Space\r\nAgency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed
  by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/conso\r\nrtium).
  Funding for the DPAC has been provided by national institutions, in particular the
  institutions participating in the Gaia Multilateral Agreement. Based on observations
  obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the
  Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported
  by the National Science Foundation under Grants No. AST-1440341 and AST-2034437
  and a collaboration including current partners Caltech, IPAC, the Weizmann Institute
  for Science, the Oskar Klein Center at Stockholm University, the University of Maryland,
  Deutsches Elektronen-Synchrotron and\r\nHumboldt University, the TANGO Consortium
  of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence
  Livermore National Laboratories, IN2P3, University\r\nof Warwick, Ruhr University
  Bochum, Northwestern University and former partners the University of Washington,
  Los Alamos National Laboratories, and Lawrence Berkeley National Laboratories. Operations
  are conducted by COO, IPAC, and UW. This work has made use of data from the Asteroid
  Terrestrialimpact Last Alert System (ATLAS) project. The Asteroid Terrestrial-impact
  Last Alert System (ATLAS) project is primarily funded to search for near earth asteroids
  through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the
  NEO search include images and catalogs from the survey area. This work was partially
  funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889, and STFC grants
  ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible
  through the contributions of the University of Hawaii Institute for Astronomy, the
  Queen’s University Belfast, the Space Telescope Science Institute, the South African\r\nAstronomical
  Observatory, and The Millennium Institute of Astrophysics (MAS), Chile.\r\nThis
  work makes use of observations from the Las Cumbres Observatory global telescope
  network. Research at Lick Observatory is partially supported by a generous gift
  from Google. A major upgrade of the Kast spectrograph on the Shane 3 m telescope
  at Lick Observatory was made possible through generous gifts from William and Marina
  Kast as well as the Heising–Simons Foundation. The Isaac Newton Telescope is operated
  on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish
  Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.This
  paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las
  Campanas Observatory, Chile. Observations reported here were obtained at the Multiple
  Mirror Telescope (MMT) Observatory, a joint facility of the Smithsonian Institution
  and the University of Arizona. Based on observations collected at Centro Astronómico
  Hispano en Andalucía (CAHA) at Calar Alto, operated jointly by Junta de Andalucía
  and Consejo Superior de Investigaciones Científicas (IAA-CSIC)."
article_number: stag505
article_processing_charge: Yes
article_type: original
arxiv: 1
author:
- first_name: Abbigail K.
  full_name: Elms, Abbigail K.
  last_name: Elms
- first_name: Stefano
  full_name: Bagnulo, Stefano
  last_name: Bagnulo
- first_name: Pier Emmanuel
  full_name: Tremblay, Pier Emmanuel
  last_name: Tremblay
- first_name: Tim
  full_name: Cunningham, Tim
  last_name: Cunningham
- first_name: James
  full_name: Munday, James
  last_name: Munday
- first_name: John
  full_name: Landstreet, John
  last_name: Landstreet
- first_name: Kareem
  full_name: El-Badry, Kareem
  last_name: El-Badry
- first_name: Ilaria
  full_name: Caiazzo, Ilaria
  id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d
  last_name: Caiazzo
  orcid: 0000-0002-4770-5388
- first_name: Carl
  full_name: Melis, Carl
  last_name: Melis
- first_name: Viktoria
  full_name: Pinter, Viktoria
  last_name: Pinter
- first_name: Alycia
  full_name: Weinberger, Alycia
  last_name: Weinberger
citation:
  ama: Elms AK, Bagnulo S, Tremblay PE, et al. Detection of a weak magnetic field
    in the Balmer emission line white dwarf WDJ1653−1001. <i>Monthly Notices of the
    Royal Astronomical Society</i>. 2026;548(1). doi:<a href="https://doi.org/10.1093/mnras/stag505">10.1093/mnras/stag505</a>
  apa: Elms, A. K., Bagnulo, S., Tremblay, P. E., Cunningham, T., Munday, J., Landstreet,
    J., … Weinberger, A. (2026). Detection of a weak magnetic field in the Balmer
    emission line white dwarf WDJ1653−1001. <i>Monthly Notices of the Royal Astronomical
    Society</i>. Oxford University Press. <a href="https://doi.org/10.1093/mnras/stag505">https://doi.org/10.1093/mnras/stag505</a>
  chicago: Elms, Abbigail K., Stefano Bagnulo, Pier Emmanuel Tremblay, Tim Cunningham,
    James Munday, John Landstreet, Kareem El-Badry, et al. “Detection of a Weak Magnetic
    Field in the Balmer Emission Line White Dwarf WDJ1653−1001.” <i>Monthly Notices
    of the Royal Astronomical Society</i>. Oxford University Press, 2026. <a href="https://doi.org/10.1093/mnras/stag505">https://doi.org/10.1093/mnras/stag505</a>.
  ieee: A. K. Elms <i>et al.</i>, “Detection of a weak magnetic field in the Balmer
    emission line white dwarf WDJ1653−1001,” <i>Monthly Notices of the Royal Astronomical
    Society</i>, vol. 548, no. 1. Oxford University Press, 2026.
  ista: Elms AK, Bagnulo S, Tremblay PE, Cunningham T, Munday J, Landstreet J, El-Badry
    K, Caiazzo I, Melis C, Pinter V, Weinberger A. 2026. Detection of a weak magnetic
    field in the Balmer emission line white dwarf WDJ1653−1001. Monthly Notices of
    the Royal Astronomical Society. 548(1), stag505.
  mla: Elms, Abbigail K., et al. “Detection of a Weak Magnetic Field in the Balmer
    Emission Line White Dwarf WDJ1653−1001.” <i>Monthly Notices of the Royal Astronomical
    Society</i>, vol. 548, no. 1, stag505, Oxford University Press, 2026, doi:<a href="https://doi.org/10.1093/mnras/stag505">10.1093/mnras/stag505</a>.
  short: A.K. Elms, S. Bagnulo, P.E. Tremblay, T. Cunningham, J. Munday, J. Landstreet,
    K. El-Badry, I. Caiazzo, C. Melis, V. Pinter, A. Weinberger, Monthly Notices of
    the Royal Astronomical Society 548 (2026).
date_created: 2026-04-19T22:07:42Z
date_published: 2026-05-01T00:00:00Z
date_updated: 2026-05-04T12:11:53Z
day: '01'
ddc:
- '520'
department:
- _id: IlCa
doi: 10.1093/mnras/stag505
external_id:
  arxiv:
  - '2603.12048'
file:
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  checksum: 75c48d70d10a9a48875f577e04da80bc
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  date_created: 2026-05-04T12:10:40Z
  date_updated: 2026-05-04T12:10:40Z
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  file_name: 2026_MNRAS_Elms.pdf
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  relation: main_file
  success: 1
file_date_updated: 2026-05-04T12:10:40Z
has_accepted_license: '1'
intvolume: '       548'
issue: '1'
language:
- iso: eng
license: https://creativecommons.org/licenses/by/4.0/
month: '05'
oa: 1
oa_version: Published Version
publication: Monthly Notices of the Royal Astronomical Society
publication_identifier:
  eissn:
  - 1365-2966
  issn:
  - 0035-8711
publication_status: published
publisher: Oxford University Press
quality_controlled: '1'
scopus_import: '1'
status: public
title: Detection of a weak magnetic field in the Balmer emission line white dwarf
  WDJ1653−1001
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: 548
year: '2026'
...