White Dwarf Merger Remnants: The DAQ Subclass
Four years after the discovery of a unique DAQ white dwarf with a hydrogen-dominated and carbon-rich atmosphere, we report the discovery of four new DAQ white dwarfs, including two that were not recognized properly in the literature. We find all five DAQs in a relatively narrow mass and temperature...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2024-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad3440 |
| _version_ | 1797202807405674496 |
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| author | Mukremin Kilic Pierre Bergeron Simon Blouin Gracyn Jewett Warren R. Brown Adam Moss |
| author_facet | Mukremin Kilic Pierre Bergeron Simon Blouin Gracyn Jewett Warren R. Brown Adam Moss |
| author_sort | Mukremin Kilic |
| collection | DOAJ |
| description | Four years after the discovery of a unique DAQ white dwarf with a hydrogen-dominated and carbon-rich atmosphere, we report the discovery of four new DAQ white dwarfs, including two that were not recognized properly in the literature. We find all five DAQs in a relatively narrow mass and temperature range of M = 1.14–1.19 M _⊙ and T _eff = 13,000–17,000 K. In addition, at least two show photometric variations due to rapid rotation with ≈10 minute periods. All five are also kinematically old, but appear photometrically young, with estimated cooling ages of about 1 Gyr based on standard cooling tracks, and their masses are roughly twice the mass of the most common white dwarfs in the solar neighborhood. These characteristics are smoking gun signatures of white dwarf merger remnants. Comparing the DAQ sample with warm DQ white dwarfs, we demonstrate that there is a range of hydrogen abundances among the warm DQ population and that the distinction between DAQ and warm DQ white dwarfs is superficial. We discuss the potential evolutionary channels for the emergence of the DAQ subclass, suggesting that DAQ white dwarfs are trapped on the crystallization sequence and may remain there for a significant fraction of the Hubble time. |
| first_indexed | 2024-04-24T08:09:18Z |
| format | Article |
| id | doaj.art-4fd55103899849bfb22c2e58f86a5852 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-04-24T08:09:18Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-4fd55103899849bfb22c2e58f86a58522024-04-17T08:21:17ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01965215910.3847/1538-4357/ad3440White Dwarf Merger Remnants: The DAQ SubclassMukremin Kilic0https://orcid.org/0000-0001-6098-2235Pierre Bergeron1https://orcid.org/0000-0003-2368-345XSimon Blouin2https://orcid.org/0000-0002-9632-1436Gracyn Jewett3https://orcid.org/0009-0009-9105-7865Warren R. Brown4https://orcid.org/0000-0002-4462-2341Adam Moss5https://orcid.org/0000-0001-7143-0890Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma , 440 W. Brooks Street, Norman, OK 73019, USADépartement de Physique, Université de Montréal , C.P. 6128, Succ. Centre-Ville, Montréal, QC, H3C 3J7, CanadaDepartment of Physics and Astronomy, University of Victoria , Victoria, BC, V8W 2Y2, CanadaHomer L. Dodge Department of Physics and Astronomy, University of Oklahoma , 440 W. Brooks Street, Norman, OK 73019, USACenter for Astrophysics , Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USAHomer L. Dodge Department of Physics and Astronomy, University of Oklahoma , 440 W. Brooks Street, Norman, OK 73019, USAFour years after the discovery of a unique DAQ white dwarf with a hydrogen-dominated and carbon-rich atmosphere, we report the discovery of four new DAQ white dwarfs, including two that were not recognized properly in the literature. We find all five DAQs in a relatively narrow mass and temperature range of M = 1.14–1.19 M _⊙ and T _eff = 13,000–17,000 K. In addition, at least two show photometric variations due to rapid rotation with ≈10 minute periods. All five are also kinematically old, but appear photometrically young, with estimated cooling ages of about 1 Gyr based on standard cooling tracks, and their masses are roughly twice the mass of the most common white dwarfs in the solar neighborhood. These characteristics are smoking gun signatures of white dwarf merger remnants. Comparing the DAQ sample with warm DQ white dwarfs, we demonstrate that there is a range of hydrogen abundances among the warm DQ population and that the distinction between DAQ and warm DQ white dwarfs is superficial. We discuss the potential evolutionary channels for the emergence of the DAQ subclass, suggesting that DAQ white dwarfs are trapped on the crystallization sequence and may remain there for a significant fraction of the Hubble time.https://doi.org/10.3847/1538-4357/ad3440White dwarf starsAtmospheric compositionStellar evolutionary typesStellar mergersDQ stars |
| spellingShingle | Mukremin Kilic Pierre Bergeron Simon Blouin Gracyn Jewett Warren R. Brown Adam Moss White Dwarf Merger Remnants: The DAQ Subclass The Astrophysical Journal White dwarf stars Atmospheric composition Stellar evolutionary types Stellar mergers DQ stars |
| title | White Dwarf Merger Remnants: The DAQ Subclass |
| title_full | White Dwarf Merger Remnants: The DAQ Subclass |
| title_fullStr | White Dwarf Merger Remnants: The DAQ Subclass |
| title_full_unstemmed | White Dwarf Merger Remnants: The DAQ Subclass |
| title_short | White Dwarf Merger Remnants: The DAQ Subclass |
| title_sort | white dwarf merger remnants the daq subclass |
| topic | White dwarf stars Atmospheric composition Stellar evolutionary types Stellar mergers DQ stars |
| url | https://doi.org/10.3847/1538-4357/ad3440 |
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