Astronomers Discover Sub-Earth Planet Orbiting Closest Single Star to Our Sun

This artist’s impression shows Barnard b, a sub-Earth-mass planet that was discovered orbiting Barnard’s star. Its signal was detected with the ESPRESSO instrument on ESO’s Very Large Telescope (VLT), and astronomers were able to confirm it with data from other instruments. An earlier promising detection in 2018 around the same star could not be confirmed by these data. On this newly discovered exoplanet, which has at least half the mass of Venus but is too hot to support liquid water, a year lasts just over three Earth days.

This artist’s impression shows Barnard b, a sub-Earth-mass planet that was discovered orbiting Barnard’s star. Its signal was detected with the ESPRESSO instrument on ESO’s Very Large Telescope (VLT), and astronomers were able to confirm it with data from other instruments. An earlier promising detection in 2018 around the same star could not be confirmed by these data. On this newly discovered exoplanet, which has at least half the mass of Venus but is too hot to support liquid water, a year lasts just over three Earth days.

Scientists have detected a new exoplanet orbiting Barnard’s star, the closest single star to our solar system, using the European Southern Observatory’s Very Large Telescope (ESO’s VLT).

Summary: A team of astronomers has discovered a sub-Earth mass planet orbiting Barnard’s star, located just six light-years away, with a year lasting only 3.15 Earth days.

Estimated reading time: 6 minutes

In a significant advancement for exoplanet research, astronomers using ESO’s Very Large Telescope (VLT) have discovered a new planet orbiting Barnard’s star, the closest single star to our Sun. This finding, published in the journal Astronomy & Astrophysics, not only expands our understanding of planetary systems in our cosmic neighborhood but also demonstrates the increasing precision of exoplanet detection techniques.

Barnard’s star, located a mere six light-years away, has long been a prime target in the search for exoplanets due to its proximity and characteristics. This discovery marks a crucial step forward in our exploration of potentially habitable worlds beyond our solar system.

A Sub-Earth Planet in a Swift Orbit

The newly discovered exoplanet, named Barnard b, is remarkable for several reasons:

  1. Mass: It has at least half the mass of Venus, making it one of the lowest-mass exoplanets known to date.
  2. Orbital period: A year on Barnard b lasts just 3.15 Earth days.
  3. Temperature: Despite its close orbit, the planet’s surface temperature is estimated to be around 125°C.

Lead author Jonay González Hernández from the Instituto de Astrofísica de Canarias in Spain explains: “Barnard b is one of the lowest-mass exoplanets known and one of the few known with a mass less than that of Earth. But the planet is too close to the host star, closer than the habitable zone.”

A Long Journey to Discovery

The path to this discovery has been a long one. Despite a promising detection in 2018, no planet orbiting Barnard’s star had been confirmed until now. The research team’s persistence over five years of observations with ESO’s VLT finally paid off.

“Even if it took a long time, we were always confident that we could find something,” says González Hernández. The team focused their search on signals from possible exoplanets within the habitable or temperate zone of Barnard’s star – the range where liquid water can exist on a planet’s surface.

Technological Precision and Future Prospects

The discovery was made possible by ESPRESSO, a highly precise instrument designed to measure the wobble of a star caused by the gravitational pull of orbiting planets. This technique, known as the radial velocity method, allows astronomers to infer the presence of planets by detecting minute changes in a star’s motion.

The research team’s findings were confirmed using data from other specialized exoplanet hunting instruments: HARPS at ESO’s La Silla Observatory, HARPS-N, and CARMENES. Interestingly, the new data do not support the existence of the exoplanet reported in 2018, highlighting the importance of continued observations and data verification in exoplanet research.

More Planets on the Horizon?

In addition to the confirmed planet, the international team found hints of three more exoplanet candidates orbiting Barnard’s star. These potential planets will require additional observations with ESPRESSO to be confirmed.

Co-author Alejandro Suárez Mascareño, also from the Instituto de Astrofísica de Canarias, notes the significance of this discovery in the broader context of exoplanet research: “The discovery of this planet, along with other previous discoveries such as Proxima b and d, shows that our cosmic backyard is full of low-mass planets.”

The Future of Exoplanet Research

This discovery sets the stage for even more exciting developments in the field of exoplanet research. ESO’s Extremely Large Telescope (ELT), currently under construction, is poised to revolutionize our ability to detect and study small, rocky planets in the temperate zones around nearby stars.

The ELT’s ANDES instrument will enable researchers to detect more of these small, rocky planets in the temperate zone around nearby stars, beyond the reach of current telescopes. Moreover, it will allow scientists to study the composition of their atmospheres, bringing us closer to answering questions about the potential for life beyond our solar system.

As our tools and techniques for exoplanet detection continue to improve, discoveries like Barnard b remind us that the universe is full of surprises, waiting to be uncovered in our cosmic neighborhood.

Quiz: Test Your Knowledge on the New Exoplanet Discovery

  1. How far is Barnard’s star from our solar system? a) 4 light-years b) 6 light-years c) 10 light-years d) 20 light-years
  2. What is the orbital period of the newly discovered planet Barnard b? a) 3.15 Earth days b) 3.15 Earth months c) 3.15 Earth years d) 31.5 Earth days
  3. What instrument was used to make this discovery? a) Hubble Space Telescope b) James Webb Space Telescope c) ESPRESSO on ESO’s Very Large Telescope d) Kepler Space Telescope

Answer Key:

  1. b) 6 light-years
  2. a) 3.15 Earth days
  3. c) ESPRESSO on ESO’s Very Large Telescope

Further Reading

  1. Original research paper: “A sub-Earth-mass planet orbiting Barnard’s star” – https://www.aanda.org/10.1051/0004-6361/202451311
  2. European Southern Observatory (ESO) website: https://www.eso.org
  3. ESPRESSO instrument information: https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/espresso/

Glossary of Terms

  1. Exoplanet: A planet that orbits a star other than the Sun.
  2. Radial Velocity Method: A technique for detecting exoplanets by measuring the small wobbles in a star’s motion caused by the gravitational pull of orbiting planets.
  3. Habitable Zone: The range of distances from a star where liquid water could exist on the surface of an orbiting planet.
  4. ESPRESSO: Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, the instrument used to make this discovery.
  5. Very Large Telescope (VLT): An array of four large telescopes operated by the European Southern Observatory in Chile.
  6. Sub-Earth: A planet with a mass lower than that of Earth.

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