For the first time in history, astronomers observe the white dwarf switch on and off. Here’s everything you need to know about the degenerate dwarf.
Astronomers observe a unique phenomenon
Also called the degenerate dwarf, the white dwarfs are stars that have burned up all the hydrogen. Hence, it is the star’s stellar core portion composed of electron-degenerate matter. It is highly dense with a mass comparable to that of the Sun. However, its volume is as small as the Earth. Thanks to a planet-hunting satellite, researchers had the chance of observing the star which was on and off. According to researchers, the remnant is feeding or accreting from its companion star. And, as it accretes, it becomes brighter.
What did the astronomers see? They had the chance to witness the brightness go down in just 30 minutes. However, previously the phenomenon was known to occur in them for several days or months. Researchers believe that something is interfering with the degenerate dwarf’s food supply. After all, the brightness of an accreting star has effects from the source it feeds on.
More on the white dwarf
According to the researchers from Durham University, this will help in understanding the physics behind accretion. After all objects like the black holes, neutron stars, and white dwarfs feed on neighboring stars. This particular star was located in TW Pictoris, 1,400 light-years away. The phenomenon, observed using NASA’s Transiting Exoplanet Survey Satellite (Tess). TW Pictoris consists of a white dwarf which feeds from an accretion disc in its surrounding. Fuelled by helium and hydrogen in the smaller companion star.
During the ON mode, the star normally feeds off the accretion disc, just like it usually does. However, the OFF mode is abrupt. Astronomers observed that the dwarf’s brightness plummeted quickly. Moreover, during this time, the amount of fuel is regulated through the ‘magnetic gating’ mechanism. “The brightness variations seen in accreting white dwarfs are generally relatively slow, occurring on timescales of days to months,” said Dr. Simone Scaringi. Dr. Scaringin is the lead author from Durham University’s Center for Extragalactic Astronomy.
“It appears to be switching on and off. is a previously unrecognized phenomenon and because we can draw comparisons with similar behavior in the much smaller neutron stars it could be an important step in helping us to better understand the process of how other accreting objects feed on the material that surrounds them and the important role of magnetic fields in this process,” he added.