Mr. Spock’s Planet Vulcan Found

This artist’s illustration shows the newly-found super-Earth orbiting 40 Eridani A. University of Florida

Sometimes science fiction anticipates scientific discovery. That exactly what happened when the Dharma Planet Survey uncovered a new super-Earth orbiting 40 Eridani A 16 light years away. Does the name faintly ring a bell? Star Trek fans will remember this as the location of Mr. Spock’s fictional planet Vulcan.

Led by Jian Ge of the University of Florida, a team of scientists used the Dharma Endowment Foundation Telescope (DEFT), a 50-inch telescope located atop Mt. Lemmon in southern Arizona, to pry it from the glare of its host star. They discovered it by measuring the a minute but cyclic change in the star’s speed caused the gravitational tug of the planet. You can read about their discovery paper here.

The “Vulcan” planet was discovered using the radial velocity method. As an unseen planet revolves around its parent star, its gravitational pull tugs the star first toward the Earth, causing the light it emits to appear bluer (blue squiggles) and then away, which causes the light to redden slightly. ESO

The planet is roughly twice the size of Earth but 8.5 times as massive and orbits every 42 days just inside the star’s optimal habitable zone. Intriguingly, that jives with characteristics of the fictional Vulcan — closer to its host star and hence hotter than Earth and more massive with a stronger gravitational pull. It’s said that Vulcans are about three times stronger than humans because of having to deal with the extra gravitational onus.

40 Eridani A first showed up in the literature as Vulcan’s home star in the 1968 publication Star Trek 2 by James Blish and Star Trek Maps (1980). Years later, Star Trek creator Gene Roddenberry along with Sallie Baliunas, Robert Donahue, and George Nassiopoulos of the Harvard-Smithsonian Center for Astrophysics, confirmed the identification of 40 Eridani A as Vulcan’s host star in a letter to Sky & Telescope magazine.

40 Eridani is 4th magnitude triple star visible with the naked eye from suburban and rurals areas in the constellation Eridanus west of Orion the Hunter. The primary star of the trio, 40 Eridani A, is accompanied by a planet twice the size of the Earth. The chart above shows the sky at around 5:30 a.m. local time in mid-late September facing south. Stellarium

40 Eridani A is an orange-colored star slightly cooler and slightly less massive than our Sun but approximately the same age, 5.6 billion years old. It even has a 10.1-year magnetic cycle much like the sun’s 11.6-year sunspot cycle. In that sense, it’s old enough and similar enough to the sun to be an ideal host star for an advanced civilization, according to Ge. Just to be clear, that part is still science fiction.

The 40 Eridani star system with its three diverse stellar types. DSS2/blue

Unlike the sun, the star has two fainter companions visible in a small telescope, 40 Eridani B and C, all three of which make a beautiful sight in a small telescope. You can get up before dawn and track down this triple wonder located west of Orion or wait until it eases it way into the evening sky in November. If you could see the star from the newly discovered planet, named 40 Eridani b, which orbits the primary star, you’d look around to see the two companion stars, one pink and the other pure white, beaming brightly from different parts of the sky. B is a white dwarf only 1½ times the size of the Earth and C a red dwarf a third the size of our sun. Here’s what they look like in a telescope.

The system is so fascinating in its own right that it’s hard not to raise an eyebrow and pronounce the discovery only logical.