Historic discovery, Sun's Core rotates four times faster than its surface
The researchers made the calculations using 16 years of observations from an instrument called GOLF (Global Oscillations at Low Frequency) on a spacecraft called Solar and Heliospheric Observatory (SOHO).
A team of researchers have recently made a historic discovery of solar seismic waves which reveals that Sun's core is rotating four times faster than its surface. The study was published by NASA on 1 August 2017 in Astronomy & Astrophysics journal.
The researchers made the calculations using 16 years of observations from an instrument called GOLF (Global Oscillations at Low Frequency) on a spacecraft called Solar and Heliospheric Observatory (SOHO). SOHO is a joint project of the European Space Agency (ESA) and NASA.
The method was developed by a team of researchers led by astronomer Eric Fossat.
How was the discovery made?
• The solar physicists use 'Helioseismology' to probe the solar interior by studying sound waves reverberating through it.
• The continuous convection of solar material beneath the surface of the Sun constantly generates higher frequency waves or pressure waves (p-waves).
• These sound waves are easily detected as the sound waves boom through the upper layers of the Sun.
• These waves pass very quickly through deeper layers and are therefore not sensitive to the Sun's core rotation.
• On the contrary, Gravity Waves (g-waves) that represent oscillations of the solar interior have no clear signature at the surface.
• Scientists have been searching for these mysterious g-waves in Sun for over 40 years, but their efforts were futile.
• However, by applying various analytical and statistical techniques on the data collected by SOHO's dedicated GOLF, a regular imprint of the g-modes on the p-modes was revealed.
• On the basis of the signature of the g-waves, scientists determined that the g-waves are shaking the structure of the sun’s core.
• The signature of the imprinted g-waves suggested that the inner core of the Sun is rotating once every week, nearly four times faster than the observed surface and intermediate layers.