Volunteers help discover record-breaking exoplanet in a binary star system

A team of astronomers and citizen scientists has discovered a record-breaking planet in the habitable zone of an unusual star system that includes two stars and possibly another world.

Planet TOI 4633 c, discovered by public scientists. Source: phys.org

Unique planetary system

Planet hunters spotted a planet similar to Neptune as it passed in front of its main star, temporarily dimming the star’s light, similar to a solar eclipse on Earth. This is what usually happens when scientists apply a method called transit. When the orbit of a celestial body lies between us and a star, it can be discovered even when it does not manifest itself in any way.

The new planet turned out to be a record for several reasons at once. Among all the transiting worlds, it is the furthest from its luminary: it takes 272 days to lap its star. In addition, the luminary is the brightest among those that have such a world in a habitable zone.

Further observations of the system revealed even more features. The star is also orbited by a still unconfirmed second planet with a 34-day orbit and possibly another luminary. The unique system provides valuable information for scientists who are trying to understand how planets form and remain in stable orbits in multiple systems. The researchers presented their discovery on April 30 in The Astrophysical Journal.

Star systems form when clouds of gas and dust begin to gather together. When two stars form side by side, they can form a pair. In this case, the probability of planet formation is halved. Therefore, the new system looks really interesting in this regard.

Help from volunteers

The newfound planet — officially named TOI 4633 c, but scientists named it Percival (after a character in the Harry Potter book series) — was first identified by citizen scientists sifting through data collected by NASA’s Transiting Exoplanet Survey Satellite (TESS). The Planet Hunters TESS program allows anyone with an Internet-connected computer to search for undiscovered planets in the data of this space telescope. 

Scientific volunteers, or citizen scientists, as they are also called, help professional astronomers sort through huge amounts of data that are too large for researchers to analyze on their own. To date, the project has allowed more than 43,000 volunteers from 90 countries to contribute to the creation of a catalog of about 25 million objects. Volunteers are especially valuable in the search for long-orbiting exoplanets, as they are difficult to identify using computers.

After 15 citizen scientists identified a possible planet, the professionals decided to take a closer look at it. Further investigation of the radial velocity of the star showed the possibility of the existence of a second world closer to the star.

What else is interesting about the new planet

Further studies of images and archival data have shown that what scientists initially thought was one star is actually two. They orbit so close to each other that it is almost impossible to see them separately from the Earth. However, archival observations of the system collected over the past 119 years have shown that it is indeed a pair of binary stars.

The new exoplanet has the second longest orbit among all the planets discovered using TESS data, and is one of five with orbits exceeding 100 days. Although scientists believe that this world is in a habitable zone, they would not recommend it as a destination for the next interstellar vacation.

TOI 4633 c has no solid surface, and its atmosphere probably consists of water vapor, hydrogen and methane. However, previous studies have shown that long-period planets are likely to have moons that may have a solid surface for the origin of life. 

A new study will help scientists make better predictions on the search for new exoplanets. After all, almost half of all sun-like stars are located in multi-star systems. 

According to phys.org

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