EX Hydrae: White Dwarf’s X-Ray Accretion Revealed by NASA

Scientists used Nasa’s IXPE to help understand magnetic fields in binary systems. 

Scientists using NASA’s Imaging X-ray Polarization Explorer (IXPE) examined EX Hydrae, a white dwarf located approximately 200 light-years away from the Earth (1,2,3). White dwarfs are Earth-sized stellar remnants formed after a star, roughly as large as the Sun, runs out of fuel and collapses (1,2). EX Hydrae is part of a binary system consisting of two stars, the white dwarf itself and a main-sequence companion star that fuses hydrogen to helium (1,2,3). EX Hydrae is classified as an intermediate polar, meaning the magnetic field is too weak to redirect all infalling matter directly to its magnetic poles, resulting in the formation of an accretion disk (1,2,4). This accretion disk is caused by Roche-lobe overflow, a process in which excess mass from the companion star’s Roche-lobe is excreted and captured by the gravitational field of the star (4). This material falls inward toward the white dwarf (1,4). While falling, the matter collides together, reaching temperatures estimated to be tens of millions Fahrenheit (1,4). This creates large gas columns that emit high-energy X-rays, whose intensity varies with the star’s rotation (1,2,4). Data collected by IXPE will help scientists better understand how other high-energy binary star systems function (1,2). 

Bibliography

1. Allen, M. (2026b, January 5). NASA’s IXPE Measures White Dwarf Star for First Time – NASA. NASA. https://www.nasa.gov/missions/ixpe/nasas-ixpe-measures-white-dwarf-star-for-first-time/ 
2. Allen, M. (2026a). A white dwarf’s cosmic feeding frenzy revealed by NASA. ScienceDaily. https://www.sciencedaily.com/releases/2026/01/260108190339.htm
3. NASA. (2024, May). Star Types – NASA Science. Science.nasa.gov; NASA. https://science.nasa.gov/universe/stars/types/ 
4. Mhlahlo, N., Buckley, D. A. H., Dhillon, V. S., Potter, S. B., Warner, B., & Woudt, P. A. (2007). Spectroscopic observations of the intermediate polar EX Hydrae in quiescence. Monthly Notices of the Royal Astronomical Society, 378(1), 211–220. https://doi.org/10.1111/j.1365-2966.2007.11762.x
5. Roche, P. (2024, January 11). What is an accretion disk and how does one form? Www.skyatnightmagazine.com. https://www.skyatnightmagazine.com/space-science/accretion-disk 

Image

1. https://www.nasa.gov/wp-content/uploads/2026/01/mit-polarized-dwarf-01-press-0.jpg