Michael Schirber in Space.com:
In a reversal of roles, a planet has gravitationally bullied its star to rotate in step with the planet’s orbit. The star’s behavior is similar to that of our Moon, which turns just fast enough to keep one face always pointing at the Earth.
It is unusual, however, to see the larger body – in this case a star 1.4 times the mass of the Sun – being tidally locked by a smaller body.
“This is truly a stellar story of ‘tail wags dog,’” said Jaymie Matthews of the University of British Columbia at the annual meeting of the Canadian Astronomical Society in Montreal last week.