ANKARA
A global team of astronomers led by a Turkish scientist has discovered four new exoplanets, one of which lies within the inner edge of its star’s habitable zone and may have an atmosphere, 90 light-years away from home.
The findings from Turkish PhD candidate Selcuk Yalcinkaya’s doctoral thesis on the “discovery and validation of four super-Earth to Neptune-sized planets around M dwarfs” were published in the October 2025 issue of Astronomy & Astrophysics, one of the world’s most prestigious publications in its field.
Yalcinkaya, who is working as a research assistant of astronomy and space sciences at Ankara University, had received a grant from the Turkish Scientific and Technological Research Institution (Tubitak) under its “International Research Fellowship Program for PhD Students,” as he conducted part of his work at the Belgium-based University of Liege.
Yalcinkaya’s research, conducted by a team of global astronomers including a Nobel laureate, leveraged “the transit and radial velocity methods,” commonly used in planet discovery.
The discoveries -- two orbiting the small, cool star TOI-5799 and one each around TOI-1743 and TOI-6223 -- were made using data from the AU Kreiken Observatory and the Turkish National Observatory.
One of the exoplanets found orbiting the “TOI-5799,” namely the “TOI-5799c,” was found to be within the star’s habitable zone, albeit 90 light-years away from Earth.
Yalcinkaya told Anadolu that the planets his team discovered were previously identified as exoplanet candidates after observations on the TESS Space Telescope.
The telescope monitors transit signals over a 30-day period in space, while researchers on Earth use observatory telescopes to identify which star in the region is emitting the signal and determine whether it originates from that star or another nearby one.
“One of the planets we discovered, the ‘TOI-6223b,’ is the size of Neptune but very close to its own star, which is why it’s called a hot Neptune,” he said. “While it has a radius similar to that of Neptune’s, we need to look at what gases are present in its atmosphere.”
“Meanwhile, the other one, the ‘TOI-1743b,’ is a super-Earth -- it is about 70% larger than our planet and it is terrestrial,” he noted. “It probably can’t retain volatile gases in its atmosphere -- it is also very close to its star and therefore hot.”
Yalcinkaya said the TOI-5799 system stands out as one of the stars hosting two of the newly discovered exoplanets -- TOI-5799b and TOI-5799c -- both about 70% larger than Earth and likely terrestrial.
While TOI-5799b orbits close to its star and is therefore hot, TOI-5799c lies within the star’s habitable zone and completes an orbit every 14 days.
“The exoplanet is at a distance where water could potentially exist as liquid due to its surface temperature of around 63 degrees Celsius (145.4 degrees F), but the atmosphere could change things a bit as we don’t know what kind of atmosphere it has,” he said. “It could be much hotter than expected or colder -- we don’t know yet.
“If there’s life there, there may be some bio-signs in its atmosphere -- we can observe this in the future to see if there’s life there or not,” he noted. “Life may exist on many planets, but if there’s life in the ‘TOI-5799c,’ it is possible to find out.”
Ozgur Basturk, a professor of astronomy and space sciences at Ankara University and also the article’s supervisor, told Anadolu that the observations were made using nearly 20 telescopes worldwide -- from Chile to Türkiye and from Mexico to the Canary Islands.
“The ‘TOI-5799c’ is a planet in the habitable zone but this does not necessarily mean that life exists there,” he said.
“We need to find out if it has an atmosphere -- this is what Yalcinkaya wishes to research next,” he noted.
Basturk stated that the James Webb Space Telescope can be used to observe the transits of the exoplanet to see if it features any signs of life in its atmosphere.
“There are no terrestrial planets with atmospheres, but this one, the ‘TOI-5799c,’ is among the few candidates,” he added.