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.
When: 1 August 2017
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