Emily Chan
A nearby star is the fastest-rotating one that astronomers have seen so far, at a latitude of about 40 degrees.
The rotation rate of the V889 Herculis is significantly different from that of the Sun and anything else experts would expect. The observation can help researchers better understand the Sun’s activity and overall stellar behavior.
It has been known that the Sun rotates the fastest at the equator. The Sun slows down at higher latitudes and is at its slowest in the polar regions.
However, V889 Herculis has defied all these expectations. Astronomers at the University of Helsinki detected a very surprising pattern in this star by looking at its star spots.
Star spots can provide information on movement in different latitudes. The activity is then used to estimate the rotational profile of stars. V889 Herculis rotates the fastest at a latitude of about 40 degrees and rotates more slowly in both the equator and polar regions.
No other star has been found to follow such a pattern. The rotational profile has not even been predicted in computer simulations.
“We applied a newly developed statistical technique to the data of a familiar star that has been studied at the University of Helsinki for years. We did not expect to see such anomalies in stellar rotation. The anomalies in the rotational profile of V889 Herculis indicate that our understanding of stellar dynamics and magnetic dynamos are insufficient,” said researcher Mikko Tuomi.
The researchers used the same technique to estimate the rotational profile of a second star, LQ Hydrae, which is 20 percent less massive than the Sun and the same age as V889 Herculis.
Its rotation appeared to turn at the same rate from the equator to the poles, indicating that the differences are very slight and cannot be detected.
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