Abstract
White dwarfs represent the last stage of evolution of stars with mass less than about eight times that of the Sun and, like other stars, are often found in binaries1,2. If the orbital period of the binary is short enough, energy losses from gravitational-wave radiation can shrink the orbit until the two white dwarfs come into contact and merge3. Depending on the component masses, the merger can lead to a supernova of type Ia or result in a massive white dwarf4. In the latter case, the white dwarf remnant is expected to be highly magnetized5,6 because of the strong magnetic dynamo that should arise during the merger, and be rapidly spinning from the conservation of the orbital angular momentum7. Here we report observations of a white dwarf, ZTF J190132.9+145808.7, that exhibits these properties, but to an extreme: a rotation period of 6.94 minutes, a magnetic field ranging between 600 megagauss and 900 megagauss over its surface, and a stellar radius of 2140−230+160 kilometres, only slightly larger than the radius of the Moon. Such a small radius implies that the star’s mass is close to the maximum white dwarf mass, or Chandrasekhar mass. ZTF J190132.9+145808.7 is likely to be cooling through the Urca processes (neutrino emission from electron capture on sodium) because of the high densities reached in its core.
| Original language | English |
|---|---|
| Pages (from-to) | 39-42 |
| Number of pages | 4 |
| Journal | Nature |
| Volume | 595 |
| Issue number | 7865 |
| DOIs | |
| State | Published - 1 Jul 2021 |
| Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2021, The Author(s), under exclusive licence to Springer Nature Limited.
Funding
This work is based on observations obtained with the Samuel Oschin 48-inch telescope and the Palomar Observatory 60-inch telescope as part of the ZTF project. ZTF is supported by the NSF under grant no. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by Caltech Optical Observatories, IPAC and the University of Washington. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA. This work has made use of data from the European Space Agency (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/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen’s University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, NASA under grant no. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, NSF grant no. AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. This work was supported by the Natural Sciences and Engineering Research Council of Canada. Acknowledgements The authors thank S.-C. Leung and S. Phinney for discussions, and N. Reindl and M. Kilic for comments. I.C. is a Sherman Fairchild Fellow at Caltech and thanks the Burke Institute at Caltech for supporting her research. J.F. acknowledges support through an Innovator Grant from the Rose Hills Foundation, and the Sloan Foundation through grant FG-2018-10515. K.B.B. thanks NASA and the Heising Simons Foundation for supporting his research. J.S. is supported by the A. F. Morrison Fellowship in Lick Observatory and by the US National Science Foundation (NSF) through grant ACI-1663688.
| Funders | Funder number |
|---|---|
| Deutsches Elektronen-Synchrotron and Humboldt University | |
| Heising Simons Foundation | |
| IPAC | |
| Max Planck Institute for Astronomy | |
| Max Planck Institute for Extraterrestrial Physics | |
| National Central University of Taiwan | |
| Pan-STARRS Project Office | |
| Weizmann Institute for Science | |
| National Science Foundation | ACI-1663688, AST-1440341 |
| National Aeronautics and Space Administration | AST-1238877, NNX08AR22G |
| Alfred P. Sloan Foundation | FG-2018-10515 |
| Gordon and Betty Moore Foundation | |
| Lawrence Berkeley National Laboratory | |
| University of Wisconsin-Milwaukee | |
| California Institute of Technology | |
| University of Washington | |
| Johns Hopkins University | |
| University of Maryland | |
| University of Hawai'i | |
| Los Alamos National Laboratory | |
| Smithsonian Astrophysical Observatory | |
| Space Telescope Science Institute | |
| Rose Hills Foundation | |
| Natural Sciences and Engineering Research Council of Canada | |
| University of Edinburgh | |
| Queen's University Belfast | |
| Durham University | |
| Max-Planck-Gesellschaft | |
| Eötvös Loránd Tudományegyetem |