Astronomers Discover Exoplanet 6 Times Bigger Than Jupiter, Orbiting Twin Suns

Hyderabad: Astronomers have discovered a massive planet named HD 143811 b, outside our solar system, orbiting two stars about 500 light‑years away from Earth. The newly identified planet is a gas giant, six times heavier than Jupiter and takes 300 Earth years to complete one orbit around its twin suns.

According to research led by astronomers at the University of Exeter, the planet is extremely young, not more than 20 million years old. It has an extremely hot surface temperature, ranging above 700-degree Celsius.

Only a few planets have ever been found orbiting twin stars, and the HD 143811 b was detected using a method called Direct Imaging, which captures very sharp telescope photos by blocking the bright light of the stars to make the planet visible.

Dr Vito Squicciarini led this research, who is an astronomer from the Department of Physics and Astronomy, University of Exeter. This research was conducted by LESIA – Observatoire de Paris under the Coupling data and techniques for Breakthroughs in Exoplanetary systems exploration (COBREX) project.

COBREX is an astrophysics project, funded by the European Research Council and led by Dr Anne-Marie Lagrange. Since 2020, the team has been observing a large database of imagery, which was taken by two major observatories in Chile — the Very Large Telescope (VLT) and the Gemini South.

This database comes from the two biggest planet-hunting programs ever done:

• GPI survey: It studied 600 stars using Gemini South
• SHINE survey: It studied 400 stars using the VLT

Even though both observatories surveyed 1,000 stars in total, each observatory had found only one new exoplanet at the time.

“We know almost nothing about how planets form around binary stars,” says Dr Squicciarini. “Very few have been found orbiting binaries, especially giant ones like this, so our find is something quite rare.”

The researchers used a powerful computer algorithm called PACO to improve old telescope images. This algorithm removed noise and bright light from the stars, making the pictures clearer. With these “cleaned‑up” images, it becomes easier to spot faint objects like planets that might have been hiding in the background.

While going through these enhanced images, Dr Squicciarini and his team noticed a small object near the twin stars that hadn’t been seen before. Its position and appearance suggested that it might be a new exoplanet, which they later confirmed with additional observations.

“We could see a previously unidentified source close to the location of the two stars,” said Dr Squicciarini. “But we needed another observation to confirm that it was orbiting the two stars and not just a spurious, farther away source projected in that position by chance.”

He said, “So, we pitched for telescope time in Chile, and in July this year, we obtained further imagery. Within an hour, we had confirmed that it was indeed a new planet – the first to be found through the project.”

HD 143811 b: Characteristics

Dr Squicciarini mentioned that scientists already knew about HD 143811 b just by looking at its position and its shared characteristics with other gas giant planets.

The HD 143811 b is understood to be made almost entirely of hydrogen and helium. It is extremely hot with a temperature of around 730 degrees Celsius, and it is about six times heavier than Jupiter.

It orbits 80 astronomical units away from its twin stars, which is at a distance greater than Pluto. At such a distance, our planet Earth would take 300 Earth years to complete a single orbit.

HD 143811 b: Twin stars

The two stars—named HD 143811 A and HD 143811 B—are very close to each other and are a bit bigger than our Sun. They are also extremely young in cosmic terms, only about 20 million years old (our Sun is 4.6 billion years old).

As mentioned above, the HD 143811 b was discovered using the Direct Imaging technique to find the planet. This method was first used in 2004, which helped to discover over 50 exoplanets, out of the nearly 6,000 known exoplanets in total.

“The importance of this find is that it could help us establish a benchmark for how such planets are formed,” adds Dr Squicciarini. “And following on from this, the question is whether planets like the Earth could be found in this kind of system? We don’t yet know the answer to this because we need to understand more about the structure of the discs from which planets form when they’re in binary systems. Maybe in a few years, with more discoveries like this, we will be able to answer these fundamental questions.”