A second candidate magnetic helium core white dwarf and 3 other variable white dwarfs in the globular cluster NGC 6397

Autor:	Marcano, Manuel Pichardo, Sandoval, Liliana E. Rivera, Maccarone, Thomas J., Rohrmann, Rene D., Althaus, Leandro G., Heinke, Craig O., Belloni, Diogo, Bahramian, Arash
Rok vydání:	2024
Předmět:	Astrophysics - Solar and Stellar Astrophysics Astrophysics - Astrophysics of Galaxies Astrophysics - High Energy Astrophysical Phenomena
Druh dokumentu:	Working Paper
Popis:	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. Comment: Accepted for publication in ApJ
Databáze:	arXiv
Externí odkaz:	http://arxiv.org/abs/2412.12375 Zobrazit plný text záznamu View this record from Arxiv