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Sun’s Core Rotates 4 Times Faster than Its Surface

S u m m a r y :
The sun’s core rotates four times faster than its surface, says a new study published in the journal Astronomy and Astrophysics. These findings might reveal further data about the formation of our star.

A Relic from the Sun’s Distant Past

An international team of astronomers might have changed the way we’d think about the rotation of the sun. It has long been assumed that the sun’s core rotates at roughly the same speed as its surface. However, the former appears to be moving 4 times faster. This finding comes with further implications concerning the formation of the sun: the study authors believe that the core rotation dates back to the time when the sun was forming 4.6 billion years ago.

The sun and its core. Photo credits: Newton Science Magazine.

“The most likely explanation is that this core rotation is left over from the period when the sun formed, some 4.6 billion years ago,” says co-author Roger Ulrich from UCLA. “It’s a surprise, and exciting to think we might have uncovered a relic of what the sun was like when it first formed.”

How The Sun Formed

More importantly, the new finding might help scientists understand how the sun formed. According to Ulrich, post sun-formation, the solar wind might have caused the rotation of the sun’s outer part to decelerate.

The core rotation is also thought to have consequences on sunspots.

Solar Acoustic Waves

Ulrich and his team started off with acoustic waves in the atmosphere of the sun. Some of these waves are known to enter the sun’s core where they interact with gravity waves. The latter have a sloshing motion, and they were detected in the solar core when the investigators studied the surface acoustic waves.

Using 16 years of observation from the GOLF (Global Oscillations at Low Frequency) equipment found on a spacecraft called SoHO (the Solar and Heliospheric Observatory), the team also calculated the time it takes for an acoustic wave to go from the solar surface into the solar core, and back again. This trip into and out of the sun appears to be affected by the sloshing movement of the gravity waves.

This marks the first time that the faster solar core rotation has been measured; otherwise, previous studies have hinted at the rotation thereof to be more rapid than the surface’s without ever quantifying it.

Solar Core Temperature

Another finding entails another difference: the solar core has a temperature of 15.7 million Kelvin while that of the surface is only around 5,800 Kelvin.


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