They thought they had discovered Spock’s planet, Vulcan, and then they noticed something strange

The scientists who announced the initial discovery also warned that it might not be a new planet at all.
Star Trek fans have already noticed that scientific discoveries and stories from the popular franchise are often intertwined. For example, Mr. Spock’s fictitious home planet, Vulcan, orbits the real star 40 Eridani A. However, scientists have long thought that a planet actually orbits the star, at least that’s what their instruments have shown.

However, a study published in The Astronomical Journal revealed that what scientists thought was a planet was actually an illusion. More specifically, an astronomical illusion caused by the pulsations and tremors of the star itself.

Scientists discovered for the first time in 2018 that about 40 Eridani A could orbit a planet. But a closer analysis of that data called into question the existence of that planet. Because it appears that precise measurements by the NASA-NSF instrument, installed a few years ago on Kitt Peak in Arizona, have “erased” that planet from orbit.

As they explain in their paper, scientists use two methods when discovering exoplanets (planets orbiting other stars). The transit method, in which they observe the light of a star and note when it declines and based on that they can conclude if something has passed in front of that star. Similar to when you pass in front of a lamp and momentarily reduce the visible part of the light.

There is another method, the radial velocity method, which is particularly important for systems with planets that, from Earth’s point of view, do not intersect the faces of their stars. Using this method, scientists track subtle shifts in starlight, a measure of the “wobble” in the star itself, as the orbiting planet’s gravity pulls it to one side and then the other.

For very large planets, the radial velocity signal generally leads to unambiguous planet detection. But the problem is with the smaller planets.
The scientists who announced the initial discovery also warned that it might not be a new planet at all. They pointed out that it is possible that the “super-Earth”, later nicknamed Vulcan, is not a planet at all, but an erratic star flicker masquerading as a planet. New analysis shows they were right to remain skeptical.

Analysis of data from Kitt Peak National Observatory’s NEID instrument showed that, in all likelihood, the planet’s signal is actually a flickering of something on the star’s surface that coincides with its 42-day rotation. Scientists can’t know exactly what it is, but they speculate that it may be the swirling of warmer and cooler layers beneath the star’s surface, called convection, combined with the star’s surface features like spots and “plagues,” which are bright, active regions. Both events can change the star’s radial velocity signals.