IISc simulations explore how magnetic white dwarfs could exceed the Chandrasekhar limit

Computer models by Indian Institute of Science researchers suggest strong magnetic fields could support a white dwarf of about 2.4 solar masses, but this remains a simulation result rather than an observed star.

For a white dwarf without strong rotation or magnetism, the standard upper mass limit is about 1.4 times the Sun’s mass. In one model described by the researchers, a magnetised carbon-oxygen white dwarf reached about 2.4 solar masses. This is a theoretical scenario, not a confirmed mass measurement of an observed star.

The team tracked stellar evolution from the main sequence to the white-dwarf stage using STARS, a stellar-evolution code developed at the University of Cambridge. They added magnetic-field effects and white-dwarf cooling, then modelled a binary system in which the compact star gains matter from a companion.

In the simulations, accumulating matter made the white dwarf denser and caused it to contract, strengthening its magnetic field. The model indicates that the field supplies additional internal pressure, helping the star resist its own gravity and support more mass. The resulting limit depends on the field configuration and other conditions.

The study was conducted by a team including Zenia Zuraiq and Banibrata Mukhopadhyay. Its findings were published in The Astrophysical Journal Letters and are consistent with the team’s arXiv preprint, which describes models of magnetised white dwarfs and says the revised mass limits depend on field geometry, accretion and cooling rates. The authors connect such objects with some unusually bright Type Ia supernovae, but their possible existence does not mean that all supernovae of this class form this way.