An artist’s concept of the previously proposed possible planet, HD 26965 b – is often compared to the fictional “Vulcan” in the Star Trek universe. Credit: JPL-Caltech
New research refutes the existence of Vulcan, a planet thought to orbit around 40 Eridani A, attributing the detected signals to the surface activity of the star.
The planet thought to orbit the star 40 Eridani A — the host of Mr. Spock’s fictional home planet, Vulcan, in the “Star Trek” universe — is actually a type of astronomical illusion caused by the pulsations and tremors of the star itself. That’s according to a new study published in Astronomical magazine.
The initial excitement and doubts that followed
The possible detection of a planet orbiting the star made famous by Star Trek caused excitement and a lot of attention when it was announced in 2018. Just five years later, the planet appeared to be on shaky ground when other researchers questioned whether it was even there. Now, precise measurements using a OUR– The NSF instrument, installed a few years ago on top of Kitt Peak in Arizona, seems to have returned the planet Vulcan even more definitively to the realm of science fiction.
Exoplanet detection methods
Two methods for discovering exoplanets—planets orbiting other stars—dominate all others in the ongoing search for strange new worlds. The transit method, observing the tiny dip in starlight as a planet crosses the face of its star, is responsible for the vast majority of detections. But the “radial velocity” method also garnered a healthy share exoplanet discoveries. This method is especially important for systems with planets that, from Earth’s point of view, do not intersect the faces of their stars. By tracking subtle shifts in starlight, scientists can measure “wobbles” in the star itself, as the gravity of orbiting planets pulls it to one side and then the other. For very large planets, the radial velocity signal generally leads to unequivocal planet detection. But not so big planets can be problematic.
Questioning the existence of Vulcan
Even the scientists who made the original, possible detection of the planet HD 26965 b – almost immediately compared to the fictional Vulcan – warned that it could turn out to be a messy stellar tremor masquerading as a planet. They reported evidence of a “super-Earth” – larger than Earth, smaller than Neptune – in a 42-day orbit around a Sun-like star about 16 light-years away. The new analysis, which uses high-precision radial velocity measurements not yet available in 2018, confirms that caution about the potential discovery was justified.
The NEID instrument clarifies doubts
Bad news for Star Trek fans comes from an instrument known as NEID, a recent addition to the National Observatory’s Kitt Peak telescope complex. NEID, like other radial velocity instruments, relies on the “Doppler” effect: shifts in a star’s light spectrum that reveal its wobbly motions. In this case, analyzing the planet’s supposed signal at different wavelengths of light, emitted from different levels of the star’s outer shell or photosphere, revealed significant differences between the individual wavelength measurements—their Doppler shifts—and the total signal when all were combined. This means, in all likelihood, that the planet’s signal is actually a flickering of something on the star’s surface that coincides with the 42-day rotation—perhaps a swirling of warmer and cooler layers beneath the star’s surface, called convection, combined with features of the star’s surface such as spots and ” plage”, which are bright, active regions. Both can change the star’s radial velocity signals.
Potential for future discoveries
Although the new discovery deprives the star 40 Eridani A of its possible Vulcan planet, at least for now, the news isn’t all bad. Demonstration of such fine-tuned radial velocity measurements promises to make sharper observational distinctions between real planets and the jitters and rattles on the surfaces of distant stars.
Even the destruction of Vulcan was predicted in the Star Trek universe. Vulcan was first identified as Spock’s home planet in the original 1960s television series. But in the 2009 film, “Star Trek,” a Romulan villain named Nero uses an artificial black hole destroy Spock’s home world.
A scientific team led by Dartmouth College astronomer Abigail Burrows, formerly of NASA’s Jet Propulsion Laboratory, published a paper describing the new result, “Death of Vulcan: NEID reveals planet candidate orbiting HD 26965 is stellar activity,” in Astronomical magazine in May 2024 (Note: HD 26965 is an alternate designation for the star, 40 Eridani A.)
Reference: “Vulcan’s Death: NEID Reveals Planet Candidate Orbiting HD 26965 Stellar Activity*” by Abigail Burrows, Samuel Halverson, Jared C. Siegel, Christian Gilbertson, Jacob Luhn, Jennifer Burt, Chad F. Bender, Arpita Roy , Ryan C. Terrien, Selma Vangstein, Suvrath Mahadevan, Jason T. Wright, Paul Robertson, Eric B. Ford, Gumundur Stefánsson, Joe P. Ninan, Cullen H. Blake, Michael W. McElwain, Christian Schwab, and Jinglin Zhao, April 26 in 2024, Astronomical magazine.
DOI: 10.3847/1538-3881/ad34d5