The discovery of a possible planet orbiting the star 40 Eridani A in 2018 caused a stir among fans of Star Treksince in that universe fictitious, a world called “Vulcan” was located at those same coordinates, just 16 light years from Earth. That was the character’s home Spockbelonging to the science fiction franchise that began in the 1960s. But today, thanks to advanced technology capable of detecting fluctuations in the radial velocity and brightness of distant stars, scientists determined that the candidate planet HD 26965 b It’s actually an illusion caused by variations in the activity of the star.
A team led by Dartmouth College astronomer Abigail Burrows published a study detailing the measurements and methods used to determine that the “Vulcan”-like planet does not exist. They analyzed data through NASA’s NEID spectrometer, which has a great capacity for measuring radial velocity.
In order to discover new exoplanetsthat is, worlds that are outside the solar system, different behaviors of the stars are observed through the analysis of the variations in brightness. On the one hand, the method of transitused by the TESS space telescope, through which the light of a star is studied and light patterns are detected. intensity reduction of its glow, which happens when a possible planet is orbiting and passes between the star and the observer.
The other alternative is the method of radial velocitywhich consists of examining certain movements of the star caused by the gravitational effect exerted by the planet, or possible planet, that orbits it. Following this “wobble” The brightness of the star appears to change color when it moves away from the observer, becoming more reddish, and when it approaches, adopting a blue tone. This happens due to the change in the perception of the wavelength of light, called “Doppler effect”. In this way the orbital period and mass of the planet can also be known.
This was the method that a group of scientists used in 2018 to propose to HD 26965 b as a candidate. The characteristics attributed to this false planet were that it was a “super Earth”, larger than Earth and smaller than Neptune, and that it had an orbit of 42 days around its star, as commented by NASA in an article.
Already in 2018, the astronomers who found the candidate warned that it could be the result of a “disorderly” activity of 40 Eridani A. This star is located approximately 16 light years from Earth and is the center of a triple star system also composed of the stars 40 Eridani B and C.
At that time there were no instruments with the capacity that NEID has, which began operating in the year 2022, to detect radial velocity based on the Doppler effect. This spectrograph can analyze data from the different outer layers of the star, and thanks to this the experts detected different values between the combination of all the signals and the individual wavelength measurements resulting from the movement of the star.
“That means that, in all likelihood, the signal from the planet is actually the flicker of something on the star’s surface that coincides with a 42-day rotation; perhaps the churning of hotter and colder layers beneath the star’s surface, called convection, combined with stellar surface features. as stains and “pests”which are bright and active regions,” they explain from NASA.
Therefore, 40 Eridani A finally It does not have any planets in orbit, at least until proven otherwise. The research that led to the classification of HD 26965 b as “false positive planet” demonstrates the great abilities that the advanced space technology to capture data from stellar variations and movements, which means that scientists are managing to determine characteristics of planets, stars and entire systems with more precision than ever.
