A planet once believed to orbit the star 40 Eridani A—home to the fictional planet Vulcan from the Star Trek universe—is actually an astronomical illusion caused by the star’s own pulses and tremors, according to a new study.

The potential discovery of a planet orbiting a star made famous by Star Trek caused excitement and garnered significant attention when announced in 2018. However, just five years later, the existence of the planet was in question as researchers debated its reality.

Now, precise measurements using a NASA-NSF instrument installed a few years ago atop Kitt Peak in Arizona have definitively relegated the planet Vulcan back to the realm of science fiction.

Two primary methods for detecting exoplanets—planets that orbit other stars—dominate the ongoing search for strange new worlds. The transit method, which observes the slight dimming of starlight when a planet crosses in front of its star, is responsible for the majority of detections.

However, the radial velocity method has also led to a significant number of exoplanet discoveries. This method is particularly important for systems with planets that do not cross their stars’ faces from Earth’s viewpoint. By tracking subtle changes in starlight, scientists can measure “wobbles” in the star itself, as the gravity of an orbiting planet pulls it in different directions. For very large planets, radial velocity signals usually lead to unambiguous detections. But smaller planets can pose problems.

Even the scientists who originally reported the possible detection of the planet HD 26965 b—quickly likened to the fictional Vulcan—cautioned that it might turn out to be chaotic stellar tremors masquerading as a planet.

They reported evidence of a “super-Earth”—larger than Earth but smaller than Neptune—in a 42-day orbit around a Sun-like star about 16 light-years away. The new analysis, using high-precision radial velocity measurements that weren’t available in 2018, confirms that caution about the possible discovery was warranted.

The disappointing news for Star Trek fans comes from an instrument known as NEID, a recent addition to the telescope complex at Kitt Peak National Observatory. NEID, like other radial velocity instruments, relies on the “Doppler effect”: changes in the spectrum of a star’s light that reveal its wobbles.

In this case, breaking down the supposed planetary signal into various light wavelengths emitted from different levels of the star’s outer layer, or photosphere, revealed significant differences between individual wavelength measurements—their Doppler shifts—and the total signal when all were combined. This means that, in all likelihood, the planetary signal is actually the flicker of something on the star’s surface that coincides with a 42-day rotation—perhaps the churning of hotter and cooler layers beneath the star’s surface, called convection, combined with stellar surface features like spots and bright active regions. Both can alter a star’s radial velocity signals.

While the new finding, at least for now, deprives the star 40 Eridani A of its possible planet Vulcan, the news is not entirely bad. The demonstration of such finely tuned radial velocity measurements offers the promise of making sharper observational distinctions between real planets and the tremors and shakes on the surfaces of distant stars.

Even the destruction of Vulcan has been foreshadowed in the Star Trek universe. Vulcan was first identified as Spock’s home planet in the original 1960s television series. However, in the 2009 Star Trek movie, a Romulan villain named Nero uses an artificial black hole to blow up Spock’s homeworld.

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