UPSC Articles
Pulsating White Dwarf
Part of: Prelims and GS III – Sci and Tech
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.
