A DEAD STAR CREATES AN ENIGMATIC SHOCK WAVE

Awhite dwarf star and its Sun-like companion are defying the known laws of nature, providing a rare window into hidden physics.

Astronomers observed the white dwarf (the exposed core left behind following the death of a low-mass star) and its stellar companion using ESO’s Very Large Telescope. In doing so, they revealed a magnificent bow shock rippling through space like the wake of a ship.

The discovery left scientists stunned and confused, because these bow shocks are usually caused by material flowing out from the central star, but the white dwarf, designated RXJ0528+2838, displays no such outpouring. Nor does it display the surrounding disc of gas and dust that is typically required to fuel such outflows.

However, the bow shock implies a persistent outflow that has lasted for at least a millennium. While RXJ0528+2838 possesses a strong magnetic field that is stealing matter from its companion, this ‘engine’ alone cannot fully explain the nebula. The strength of a dwarf’s magnetic field would only keep the bow shock alive for a few hundred years.

This elusive structure challenges the standard picture of how matter moves and interacts in binary star systems. Astronomers hope that observations with the European Southern Observatory's forthcoming Extremely Large Telescope should be able to provide us with deeper insights. For now, though, the mysterious arc of RXJ0528+2838 remains a beautiful, unexplained beacon in the dark.

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www.eso.org/public/archives/releases/sciencepapers/eso2601/eso2601a.pdf