Physics and Astronomy Faculty Publications and Presentations
Document Type
Article
Publication Date
1-4-2025
Abstract
Using archival Hubble Space Telescope observations, we report the discovery of four variable low-mass white dwarfs (WDs; 0.18 M⊙ ≤ M ≤ 0.5 M⊙) in the globular cluster NGC 6397. One source exhibits a periodic optical modulation of 5.21 ± 0.02 hr, 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 ∼0.11 to 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.
Recommended Citation
Marcano, Manuel Pichardo, Liliana E. Rivera Sandoval, Thomas J. Maccarone, Rene D. Rohrmann, Leandro G. Althaus, Craig O. Heinke, Diogo Belloni, and Arash Bahramian. "A second candidate magnetic helium core white dwarf and 3 other variable white dwarfs in the globular cluster NGC 6397." The Astrophysical Journal 979, no. 2 (2025): 167. https://doi.org/10.3847/1538-4357/ada144
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Publication Title
The Astrophysical Journal
DOI
10.3847/1538-4357/ada144
Comments
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