Caiazzo, I. orcid.org/0000-0002-4770-5388, Burdge, K.B. orcid.org/0000-0002-7226-836X, Tremblay, P.-E. et al. (35 more authors) (2023) A rotating white dwarf shows different compositions on its opposite faces. Nature, 620 (7972). pp. 61-66. ISSN 0028-0836
Abstract
White dwarfs, the extremely dense remnants left behind by most stars after their death, are characterized by a mass comparable to that of the Sun compressed into the size of an Earth-like planet. In the resulting strong gravity, heavy elements sink towards the centre and the upper layer of the atmosphere contains only the lightest element present, usually hydrogen or helium 1,2. Several mechanisms compete with gravitational settling to change a white dwarf’s surface composition as it cools 3, and the fraction of white dwarfs with helium atmospheres is known to increase by a factor of about 2.5 below a temperature of about 30,000 kelvin 4–8; therefore, some white dwarfs that appear to have hydrogen-dominated atmospheres above 30,000 kelvin are bound to transition to be helium-dominated as they cool below it. Here we report observations of ZTF J203349.8+322901.1, a transitioning white dwarf with two faces: one side of its atmosphere is dominated by hydrogen and the other one by helium. This peculiar nature is probably caused by the presence of a small magnetic field, which creates an inhomogeneity in temperature, pressure or mixing strength over the surface 9–11. ZTF J203349.8+322901.1 might be the most extreme member of a class of magnetic, transitioning white dwarfs—together with GD 323 (ref. 12), a white dwarf that shows similar but much more subtle variations. This class of white dwarfs could help shed light on the physical mechanisms behind the spectral evolution of white dwarfs.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 © The Author(s). This is an author-produced version of a paper subsequently published in Nature. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Compact astrophysical objects; Stellar evolution |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Funding Information: | Funder Grant number European Research Council 340040 SCIENCE AND TECHNOLOGY FACILITIES COUNCIL ST/V000853/1 Engineering and Physical Sciences Research Council 2263443 SCIENCE AND TECHNOLOGY FACILITIES COUNCIL ST/R003424/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 17 Aug 2023 09:41 |
Last Modified: | 22 Nov 2023 12:47 |
Status: | Published |
Publisher: | Springer Science and Business Media LLC |
Refereed: | Yes |
Identification Number: | 10.1038/s41586-023-06171-9 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:202532 |