White dwarf switch on and offDate: 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 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.