For the first time, astronomers have observed a white dwarf star ‘switching on and off’ in less than 30 minutes. The researchers, led by Durham University in the United Kingdom, announced on October 18 that they used NASA’s Transiting Exoplanet Survey Satellite (TESS) to observe the unusual phenomenon, which had previously only been observed over a period of days and months. The British university team observed the phenomenon in the solar system TW Pictoris, which is 1,400 light-years away from Earth, using TESS data.
University of Durham researchers said that the particular white dwarf which showed the phenomena is known to be “accreting, or feeding from an orbiting companion star. Our astronomers saw it lose brightness in 30 minutes, a process only previously seen in accreting white dwarfs over a period of several days to months.”
The official release elaborated on the incident, stating that the brightness of the accreting white dwarf is affected by the amount of material surrounding it, which it feeds on. Astronomers believe that what they have seen could be changes to the white dwarf’s surface magnetic field. Notably, when the mode is “on,” the white dwarf star normally “feeds off” the accretion disc before the system “suddenly and abruptly” turns “off” and the brightness decreases.
Why the system goes ‘off’?
The researchers also noted in the statement that when the system ‘abruptly’ turns ‘off,’ the magnetic field of the white dwarf star spins so fast that it hinders the amount of ‘food’ that the white dwarf star can receive. According to the astronomers, this is known as magnetic gating. The shortage of ‘food’ for the star leads to “semi-regular small increases in brightness seen by the astronomers. After some time, the system sporadically turns “on” again, and the brightness increases back to its original level.”
The full research paper has been published in the journal Nature Astronomy and the study was led by Dr Simone Scaringi in Durham University’s Centre for Extragalactic Astronomy. NASA’s TESS is normally used to spot planets outside of the solar system.
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