Skip to main content

Astronomers spot a new planet orbiting our neighboring star

At just over four light-years away, the low-mass star Proxima Centauri is practically next door to us, cosmically speaking. It is known to host two exoplanets, but recent research using the European Southern Observatory’s Very Large Telescope (ESO’s VLT) has shown that these two planets may have a baby brother, in the form of one of the lightest exoplanets ever found.

The newly discovered planet, called Proxima d, orbits extremely close to its star at just 2.5 million miles away — less than one-tenth of the distance between Mercury and the sun. It is so close that it takes just five days to complete an orbit, meaning it is too close to be in the habitable zone (where liquid water could be present on its surface).

This artist’s impression shows a close-up view of Proxima d, a planet candidate recently found orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System.
This artist’s impression shows a close-up view of Proxima d, a planet candidate recently found orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. ESO/L. Calçada

The planet is just a quarter of Earth’s mass, making it extremely light by exoplanet standards. “The discovery shows that our closest stellar neighbor seems to be packed with interesting new worlds, within reach of further study and future exploration,” said lead author of the study João Faria in a statement.

The tiny mass of the exoplanet made it hard to spot, so after initial observations with the ESO’s 3.6-meter telescope, the researchers turned to the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) instrument on the VLT. “After obtaining new observations, we were able to confirm this signal as a new planet candidate,” Faria says. “I was excited by the challenge of detecting such a small signal and, by doing so, discovering an exoplanet so close to Earth.”

Many exoplanets are discovered using the transit method, in which astronomers look for small dips in the brightness of a star caused when a planet passes between the star and us. But this exoplanet was discovered using a different method called the radial velocity technique, looking for tiny wobbles in the movements of a star caused by the gravity of a passing planet. Because the gravitational wobble caused by a light planet like Proxima d is so small, traditionally the radial velocity method has been used primarily to search for larger planets.

“This achievement is extremely important,” said Pedro Figueira, ESPRESSO instrument scientist at ESO in Chile. “It shows that the radial velocity technique has the potential to unveil a population of light planets, like our own, that are expected to be the most abundant in our galaxy and that can potentially host life as we know it.”

The research is published in the journal Astronomy & Astrophysics.

Editors' Recommendations

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
Astronomers discover extremely hot exoplanet with ‘lava hemisphere’
Like Kepler-10 b, illustrated above, the exoplanet HD 63433 d is a small, rocky planet in a tight orbit of its star. HD 63433 d is the smallest confirmed exoplanet younger than 500 million years old. It's also the closest discovered Earth-sized planet this young, at about 400 million years old.

Astronomers have discovered an Earth-sized exoplanet with an unusually extreme climate where one half of the planet is thought to be covered in lava. The planet HD 63433 d is tidally locked, meaning one side of it always faces its star while the other half always faces out into space, creating a huge difference in temperatures between the planet's two faces.

Like Kepler-10 b, illustrated above, the exoplanet HD 63433 d is a small, rocky planet in a tight orbit of its star. HD 63433 d is the smallest confirmed exoplanet younger than 500 million years old.  NASA/Ames/JPL-Caltech/T. Pyle

Read more
James Webb spots tiniest known brown dwarf in stunning star cluster
The central portion of the star cluster IC 348. Astronomers combed the cluster in search of tiny, free-floating brown dwarfs.

A new image from the James Webb Space Telescope shows a stunning view of a star cluster that contains some of the smallest brown dwarfs ever identified. A brown dwarf, also sometimes known as a failed star, is an object halfway between a star and a planet -- too big to be a planet but not large enough to sustain the nuclear fusion that defines a star.

It may sound surprising, but the definition of when something stops being a planet and starts being a star is, in fact, a little unclear. Brown dwarfs differ from planets in that they form like stars do, collapsing due to gravity, but they don't sustain fusion, and their size can be comparable to large planets. Researchers study brown dwarfs to learn about what makes the difference between these two classes of objects.

Read more
Astronomers spot rare star system with six planets in geometric formation
Orbital geometry of HD110067: Tracing a link between two neighbour planets at regular time intervals along their orbits, creates a pattern unique to each couple. The six planets of the HD110067 system together create a mesmerising geometric pattern due to their resonance-chain.

Astronomers have discovered a rare star system in which six planets orbit around one star in an elaborate geometrical pattern due to a phenomenon called orbital resonance. Using both NASA's Transiting Exoplanet Survey Satellite (TESS) and the European Space Agency's (ESA) CHaracterising ExOPlanet Satellite (CHEOPS), the researchers have built up a picture of the beautiful, but complex HD110067 system, located 100 light-years away.

The six planets of the system orbit in a pattern whereby one planet completes three orbits while another does two, and one completes six orbits while another does one, and another does four orbits while another does three, and so one. The six planets form what is called a "resonant chain" where each is in resonance with the planets next to it.

Read more