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Current Affairs

White dwarf switch on and off

Date: 26 October 2021 Tags: Space


A team of international astronomers recently observed a white dwarf lose its brightness in 30 minutes.



The loosing of brightness by a white dwarf is not new but it usually takes place over a period of several days to months.



  • A white dwarf is usually half the size of our Sun and has a surface gravity 100,000 times that of Earth.  Stars become white dwarf when it exhausts all its hydrogen energy.

  • Scientists have discovered many white dwarfs using the Hubble Space telescope and Transiting Exoplanet Survey Satellite (TESS).


The recent discovery

  • The phenomenon was observed by researchers using NASA’s Transiting Exoplanet Survey Satellite (TESS). 

  • The discovered white dwarf is part of binary system called TW Pictoris. In this system a star and a white dwarf orbit each other.

  • The closeness between planet and white dwarf allows material to be transferred from the planet to white dwarf. These materials form an accretion disk.

  • The binary system is about 1400 light years from Earth. The TW Pictoris is a part of Pictoris constellation.


The occurrence

  • The donor feeder material moves closer towards the white dwarf that helps it become brighter. Sometimes the donor system completely stops feeding the disc.

  • The accretion disk takes about 1-2 months to drain most of the material. The white dwarf is still bright during this period.

  • The darkness may have occurred due to a phenomenon known as magnetic gating during which magnetic field creates a barrier disrupting its energy to glow.



The study provides understanding of how black holes and neutron stars feed material from their nearby stars.