Context A team of astronomers, using NASA’s Transiting Exoplanet Survey Satellite (TESS) have reported a unique phenomenon in a white dwarf about 1,400 light years from Earth.
They saw the white dwarf lose its brightness in 30 minutes.
About white dwarf
A white dwarf is what stars like the Sun become after they have exhausted their nuclear fuel.
Near the end of its nuclear burning stage, this type of star expels most of its outer material, creating a planetary nebula.
Only the hot core of the star remains.
This core becomes a very hot white dwarf, with a temperature exceeding 100,000 Kelvin.
The white dwarf cools down over the next billion years or so.
A pulsating white dwarf is a white dwarf star whose luminosity varies due to non-radial gravity wave pulsations within itself.
It’s switch on and off mode
As per scientists,in this system the donor star in orbit around the white dwarf keeps feeding the accretion disk.
An accretion disk is a structure formed by diffuse material in orbital motion around a massive central body. The central body is typically a star.
As the accretion disk material slowly sinks closer towards the white dwarf it generally becomes brighter(on mode).
During the ‘on’ mode, the white dwarf feeds off the accretion disk as it normally would.
Suddenly and abruptly the system turns ‘off’ and its brightness plummets.
When this happens the magnetic field is spinning so rapidly that a centrifugal barrier stops the fuel from the accretion disk constantly falling on to the white dwarf.
The new discovery will help the astronomers understand the physics behind accretion – how black holes and neutron stars feed material from their nearby stars.
About Transiting Exoplanet Survey Satellite (TESS)
TESS is a space telescope for NASA’s Explorers program, designed to search for exoplanets using the transit method in an area 400 times larger than that covered by the Kepler mission.
It was launched in 2018 by Falcon rocket system.
Using the Hubble Space telescope and TESS, astronomers have identified several white dwarfs over the years.
