| Title: |
A half ring of ionized circumstellar material trapped in the magnetosphere of a white dwarf merger remnant |
| Authors: |
Cristea, Andrei-Alexandru; Caiazzo, Ilaria; Cunningham, Tim; Raymond, John C.; Vennes, Stephane; Kawka, Adela; Desai, Aayush A; Miller, David R.; Hermes, J. J.; Fuller, Jim; Heyl, Jeremy; van Roestel, Jan; Burdge, Kevin B.; Rodriguez, Antonio C.; Pelisoli, Ingrid; Gänsicke, Boris T.; Szkody, Paula; Kenyon, Scott J.; Vanderbosch, Zach; Drake, Andrew; Ferrario, Lilia; Wickramasinghe, Dayal; Karambelkar, Viraj R.; Justham, Stephen; Pakmor, Ruediger; El-Badry, Kareem; Prince, Thomas; Kulkarni, S. R.; Graham, Matthew J.; Masci, Frank J.; Groom, Steven L.; Purdum, Josiah; Dekany, Richard; Bellm, Eric C. |
| Source: |
Cristea A-A, Caiazzo I, Cunningham T, et al. A half ring of ionized circumstellar material trapped in the magnetosphere of a white dwarf merger remnant. Astronomy & Astrophysics . 2026;706. doi: 10.1051/0004-6361/202556432 |
| Publisher Information: |
EDP Sciences |
| Publication Year: |
2026 |
| Collection: |
IST Austria Research Explorer (Institute of Science and Technology) |
| Subject Terms: |
ddc:520 |
| Description: |
Many white dwarfs are observed in compact double white dwarf binaries, and through the emission of gravitational waves, a large fraction are destined to merge. The merger remnants that do not explode in a Type Ia supernova are expected to initially be rapidly rotating and highly magnetized. In this work, we present our discovery of the variable white dwarf ZTF J200832.79+444939.67, hereafter ZTF J2008+4449, as a likely merger remnant showing signs of circumstellar material without a stellar or substellar companion. The nature of ZTF J2008+4449 as a merger remnant is supported by its physical properties: it is hot (35 500 ± 300 K) and massive (1.12 ± 0.03 M ⊙ ), rapidly rotating with a period of ≈6.6 minutes, and likely possesses exceptionally strong magnetic fields (∼400−600 MG) at its surface. Remarkably, we detect a significant period derivative of (1.80 ± 0.09)×10 −12 s/s, indicating that the white dwarf is spinning down, and a soft X-ray emission that is inconsistent with photospheric emission. As the presence of a mass-transferring stellar or brown dwarf companion is excluded by infrared photometry, the detected spin-down and X-ray emission could be tell-tale signs of a magnetically driven wind or of interaction with circumstellar material, possibly originating from the fallback of gravitationally bound merger ejecta or from the tidal disruption of a planetary object. We also detect Balmer emission, which requires the presence of ionized hydrogen in the vicinity of the white dwarf, showing Doppler shifts as high as ≈2000 km s −1 . The unusual variability of the Balmer emission on the spin period of the white dwarf is consistent with the trapping of a half ring of ionized gas in the magnetosphere of the white dwarf. |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| ISSN: |
0004-6361; 1432-0746 |
| Relation: |
info:eu-repo/semantics/altIdentifier/issn/0004-6361; info:eu-repo/semantics/altIdentifier/e-issn/1432-0746 |
| Availability: |
https://research-explorer.ista.ac.at/record/21274; https://research-explorer.ista.ac.at/download/21274/21350 |
| Rights: |
info:eu-repo/semantics/openAccess |
| Accession Number: |
edsbas.9B51BFE1 |
| Database: |
BASE |