A planet thought to orbit the star 40 Eridani A—famously known as Mr. Spock’s home planet, Vulcan, from “Star Trek”—turns out to be an illusion caused by the star’s own activity, according to a new study.
Astronomer Abigail Burrows of Dartmouth College, along with her team, has published a paper titled “The death of Vulcan: NEID reveals the planet candidate orbiting HD 26965 is stellar activity” in The Astronomical Journal.
HD 26965 is another name for 40 Eridani A.
In 2018, the possible discovery of a planet orbiting this star generated excitement, especially among “Star Trek” fans. However, doubts soon arose about its existence.
Now, precise measurements from a NASA-NSF instrument atop Kitt Peak in Arizona have shown that Vulcan is indeed just a part of science fiction.
There are two main methods for detecting exoplanets, which are planets orbiting other stars. The transit method, which observes the slight dimming of starlight as a planet crosses in front of its star, has led to most exoplanet discoveries.
The radial velocity method, which measures the star’s “wobble” caused by an orbiting planet’s gravitational pull, is also significant.
For large planets, the radial velocity method provides clear results. However, detecting smaller planets can be tricky. The scientists who initially reported the possible discovery of planet HD 26965 b (compared to the fictional Vulcan) noted it might just be stellar jitters.
They had detected a “super-Earth” in a 42-day orbit around a star 16 light-years away. The latest analysis, using high-precision radial velocity measurements unavailable in 2018, confirms their caution was justified.
The disappointing news for “Star Trek” fans comes from the NEID instrument at Kitt Peak National Observatory. NEID uses the Doppler effect to detect shifts in the light spectrum of a star, revealing its wobbling motion.
In this case, analyzing the supposed planet signal at different wavelengths of light from the star’s outer shell (photosphere) showed significant differences between individual measurements and the total signal.
This suggests that the planet signal is actually caused by activity on the star’s surface. It could be the result of convection (movement of hotter and cooler layers beneath the star’s surface) or surface features like spots and bright regions called plages. Both can affect a star’s radial velocity signals.
While this finding means that star 40 Eridani A does not have the planet Vulcan, it also demonstrates the capability of advanced radial velocity measurements to distinguish between real planets and stellar activity.
Interestingly, the “Star Trek” universe also anticipated the destruction of Vulcan. In the 2009 film “Star Trek,” a Romulan villain uses an artificial black hole to destroy Spock’s home world.
