A rotating white dwarf shows different compositions on its opposite faces

doi:10.1038/s41586-023-06171-9

. 2023 Aug;620(7972):61-66.

doi: 10.1038/s41586-023-06171-9. Epub 2023 Jul 19.

A rotating white dwarf shows different compositions on its opposite faces

Ilaria Caiazzo¹, Kevin B Burdge^{2

3}, Pier-Emmanuel Tremblay⁴, James Fuller⁵, Lilia Ferrario⁶, Boris T Gänsicke⁴, J J Hermes⁷, Jeremy Heyl⁸, Adela Kawka⁹, S R Kulkarni⁵, Thomas R Marsh⁴, Przemek Mróz¹⁰, Thomas A Prince⁵, Harvey B Richer⁸, Antonio C Rodriguez⁵, Jan van Roestel^{5

11}, Zachary P Vanderbosch⁵, Stéphane Vennes⁶, Dayal Wickramasinghe⁶, Vikram S Dhillon^{12

13}, Stuart P Littlefair¹², James Munday⁴, Ingrid Pelisoli⁴, Daniel Perley¹⁴, Eric C Bellm¹⁵, Elmé Breedt¹⁶, Alex J Brown¹², Richard Dekany¹⁷, Andrew Drake⁵, Martin J Dyer¹², Matthew J Graham⁵, Matthew J Green¹⁸, Russ R Laher¹⁹, Paul Kerry¹², Steven G Parsons¹², Reed L Riddle⁵, Ben Rusholme¹⁹, Dave I Sahman¹²

Affiliations

¹ Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA, USA. ilariac@caltech.edu.
² Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
³ Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA, USA.
⁴ Department of Physics, University of Warwick, Coventry, UK.
⁵ Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA, USA.
⁶ Mathematical Sciences Institute, The Australian National University, Canberra, Australian Capital Territory, Australia.
⁷ Department of Astronomy and Institute for Astrophysical Research, Boston University, Boston, MA, USA.
⁸ Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada.
⁹ International Centre for Radio Astronomy Research, Curtin University, Perth, Western Australia, Australia.
¹⁰ Astronomical Observatory, University of Warsaw, Warsaw, Poland.
¹¹ Anton Pannekoek Institute, University of Amsterdam, Amsterdam, The Netherlands.
¹² Department of Physics and Astronomy, University of Sheffield, Sheffield, UK.
¹³ Instituto de Astrofísica de Canarias, La Laguna, Spain.
¹⁴ Astrophysics Research Institute, Liverpool John Moores University, Liverpool, UK.
¹⁵ Department of Astronomy, University of Washington, Seattle, WA, USA.
¹⁶ Institute of Astronomy, University of Cambridge, Cambridge, UK.
¹⁷ Caltech Optical Observatories, California Institute of Technology, Pasadena, CA, USA.
¹⁸ Department of Astrophysics, School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel.
¹⁹ IPAC, California Institute of Technology, Pasadena, CA, USA.

PMID: 37468630
DOI: 10.1038/s41586-023-06171-9

Free article

A rotating white dwarf shows different compositions on its opposite faces

Ilaria Caiazzo et al. Nature. 2023 Aug.

Free article

. 2023 Aug;620(7972):61-66.

doi: 10.1038/s41586-023-06171-9. Epub 2023 Jul 19.

Authors

Affiliations

¹ Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA, USA. ilariac@caltech.edu.
² Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
³ Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA, USA.
⁴ Department of Physics, University of Warwick, Coventry, UK.
⁵ Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA, USA.
⁶ Mathematical Sciences Institute, The Australian National University, Canberra, Australian Capital Territory, Australia.
⁷ Department of Astronomy and Institute for Astrophysical Research, Boston University, Boston, MA, USA.
⁸ Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada.
⁹ International Centre for Radio Astronomy Research, Curtin University, Perth, Western Australia, Australia.
¹⁰ Astronomical Observatory, University of Warsaw, Warsaw, Poland.
¹¹ Anton Pannekoek Institute, University of Amsterdam, Amsterdam, The Netherlands.
¹² Department of Physics and Astronomy, University of Sheffield, Sheffield, UK.
¹³ Instituto de Astrofísica de Canarias, La Laguna, Spain.
¹⁴ Astrophysics Research Institute, Liverpool John Moores University, Liverpool, UK.
¹⁵ Department of Astronomy, University of Washington, Seattle, WA, USA.
¹⁶ Institute of Astronomy, University of Cambridge, Cambridge, UK.
¹⁷ Caltech Optical Observatories, California Institute of Technology, Pasadena, CA, USA.
¹⁸ Department of Astrophysics, School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel.
¹⁹ IPAC, California Institute of Technology, Pasadena, CA, USA.

PMID: 37468630
DOI: 10.1038/s41586-023-06171-9

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 cools³, 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.

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Bédard A. Bédard A. Astrophys Space Sci. 2024;369(4):43. doi: 10.1007/s10509-024-04307-5. Epub 2024 Apr 26. Astrophys Space Sci. 2024. PMID: 38681903 Free PMC article. Review.

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[1] Schatzman, E. White Dwarfs (North-Holland Publishing Co., 1958).

[2] Schatzman, E. White Dwarfs (North-Holland Publishing Co., 1958).

[3] Paquette, C., Pelletier, C., Fontaine, G. & Michaud, G. Diffusion in white dwarfs: new results and comparative study. Astrophys. J. Suppl. Ser. 61, 197 (1986). - DOI

[4] Paquette, C., Pelletier, C., Fontaine, G. & Michaud, G. Diffusion in white dwarfs: new results and comparative study. Astrophys. J. Suppl. Ser. 61, 197 (1986). - DOI

[5] Fontaine, G. & Wesemael, F. Recent advances in the theory of white dwarf spectral evolution. In IAU Colloquium 95: Second Conference on Faint Blue Stars (eds Philip, A. G. D. et al.) 319–326 (IAU, 1987).

[6] Fontaine, G. & Wesemael, F. Recent advances in the theory of white dwarf spectral evolution. In IAU Colloquium 95: Second Conference on Faint Blue Stars (eds Philip, A. G. D. et al.) 319–326 (IAU, 1987).

[7] Green, R. F., Schmidt, M. & Liebert, J. The Palomar–Green catalog of ultraviolet-excess stellar objects. Astrophys. J. Suppl. Ser. 61, 305 (1986). - DOI

[8] Green, R. F., Schmidt, M. & Liebert, J. The Palomar–Green catalog of ultraviolet-excess stellar objects. Astrophys. J. Suppl. Ser. 61, 305 (1986). - DOI

[9] Liebert, J. et al. Temperatures for hot and pulsating DB white dwarfs obtained with the IUE Observatory. Astrophys. J. 309, 241 (1986). - DOI

[10] Liebert, J. et al. Temperatures for hot and pulsating DB white dwarfs obtained with the IUE Observatory. Astrophys. J. 309, 241 (1986). - DOI

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A rotating white dwarf shows different compositions on its opposite faces

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A rotating white dwarf shows different compositions on its opposite faces

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Abstract

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