A second candidate magnetic helium core white dwarf and 3 other variable white dwarfs in the globular cluster NGC 6397
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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866915067055833088 |
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| author | Marcano, Manuel Pichardo Sandoval, Liliana E. Rivera Maccarone, Thomas J. Rohrmann, Rene D. Althaus, Leandro G. Heinke, Craig O. Belloni, Diogo Bahramian, Arash |
| author_facet | Marcano, Manuel Pichardo Sandoval, Liliana E. Rivera Maccarone, Thomas J. Rohrmann, Rene D. Althaus, Leandro G. Heinke, Craig O. Belloni, Diogo Bahramian, Arash |
| contents | Using archival Hubble Space Telescope observations, we report the discovery of four variable low-mass white dwarfs ($0.18 \, M_\odot \leq M \leq 0.5 \,M_\odot$) in the globular cluster NGC 6397. One source exhibits a periodic optical modulation of $5.21 \pm 0.02$ hours, which we interpret as potentially due to the rotation of a magnetic helium core WD (He WD). This makes this candidate the second magnetic He WD in NGC 6397, and one of the few He WDs with a measured rotation period. The other three candidates show aperiodic variability, with a change in magnitude ranging from $\sim 0.11-0.6$. These discoveries highlight the importance of high-cadence photometric surveys in dense stellar environments. Follow-up spectroscopic observations are needed to confirm the nature of the variability of these systems. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2412_12375 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | A second candidate magnetic helium core white dwarf and 3 other variable white dwarfs in the globular cluster NGC 6397 Marcano, Manuel Pichardo Sandoval, Liliana E. Rivera Maccarone, Thomas J. Rohrmann, Rene D. Althaus, Leandro G. Heinke, Craig O. Belloni, Diogo Bahramian, Arash Solar and Stellar Astrophysics Astrophysics of Galaxies High Energy Astrophysical Phenomena Using archival Hubble Space Telescope observations, we report the discovery of four variable low-mass white dwarfs ($0.18 \, M_\odot \leq M \leq 0.5 \,M_\odot$) in the globular cluster NGC 6397. One source exhibits a periodic optical modulation of $5.21 \pm 0.02$ hours, which we interpret as potentially due to the rotation of a magnetic helium core WD (He WD). This makes this candidate the second magnetic He WD in NGC 6397, and one of the few He WDs with a measured rotation period. The other three candidates show aperiodic variability, with a change in magnitude ranging from $\sim 0.11-0.6$. These discoveries highlight the importance of high-cadence photometric surveys in dense stellar environments. Follow-up spectroscopic observations are needed to confirm the nature of the variability of these systems. |
| title | A second candidate magnetic helium core white dwarf and 3 other variable white dwarfs in the globular cluster NGC 6397 |
| topic | Solar and Stellar Astrophysics Astrophysics of Galaxies High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2412.12375 |