Potentially Habitable Planet around Struve 2398 B…
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Potentially Habitable Planet around Struve 2398 B
https://en.wikipedia.org/wiki/Struve\_2398 https://en.wikipedia.org/wiki/Struve_2398
https://arxiv.org/abs/2601.22815
I overlooked this I think, since the Habitable Worlds Catolog hasn't been updated in 2 years, and this was found in 2025 (arxiv paper in January 2026). It's a very intriguing discovery though. And is now part of the list of the closest known exoplanets.
The star is a quarter the size and mass of the Sun, making it larger and brighter than Proxima Centauri (which is 12% of the mass). It's the secondary member of a binary red dwarf system. The primary is about a third the mass and size of the Sun, and they're separated by 63 AU. Both are flare stars, but I don't know exactly how much they flare. Though, I think this research is still relevant in that regard: https://academic.oup.com/mnras/article/507/2/1723/6339287?login=false&guestAccessKey= In that flares around convective red dwarfs happen at high latitudes, and would miss orbiting planets.
The binary pair is also much older than the Sun, about 8.7 billion years old.
Both systems have planetary systems, though both systems have only been found in the last few years. The primary star has 1 known planet so far, and the secondary star has 2, one confirmed, one unconfirmed.
The recently found potentially habitable exoplanet orbits the secondary member every 37.9 days at a distance of 0.139 AU, so it's likely tidally locked if it has a circular orbit (or in spin resonance like Mercury if it has an elliptical orbit).
Based on the star's luminosity and the planet's distance from the star, it receives a similar, but slightly higher amount of starlight as Mars receives compared to Earth (Flux of 0.47 vs 0.43).
The planet isn't known to transit, so the planet was found with radial velocity, with an estimated mass of 3.4 Earths. Unlike other recently found exoplanets in the habitable zone, with masses between 5-7 Earth masses (Like GJ 887d, GJ 3998d, 55 Cnc Bc), this is a relatively lower-mass Super-Earth. So it may be more likely to be rocky, though without a radius to figure out the density and bulk composition, that's unknown.
A radius of between 1.6-1.7 Earth's would give the planet a density similar to Mars (71%) or moderately less than Earth (83%), with a surface gravity 17-32% higher than Earth's.
#space
https://en.wikipedia.org/wiki/Struve\_2398 https://en.wikipedia.org/wiki/Struve_2398
https://arxiv.org/abs/2601.22815
I overlooked this I think, since the Habitable Worlds Catolog hasn't been updated in 2 years, and this was found in 2025 (arxiv paper in January 2026). It's a very intriguing discovery though. And is now part of the list of the closest known exoplanets.
The star is a quarter the size and mass of the Sun, making it larger and brighter than Proxima Centauri (which is 12% of the mass). It's the secondary member of a binary red dwarf system. The primary is about a third the mass and size of the Sun, and they're separated by 63 AU. Both are flare stars, but I don't know exactly how much they flare. Though, I think this research is still relevant in that regard: https://academic.oup.com/mnras/article/507/2/1723/6339287?login=false&guestAccessKey= In that flares around convective red dwarfs happen at high latitudes, and would miss orbiting planets.
The binary pair is also much older than the Sun, about 8.7 billion years old.
Both systems have planetary systems, though both systems have only been found in the last few years. The primary star has 1 known planet so far, and the secondary star has 2, one confirmed, one unconfirmed.
The recently found potentially habitable exoplanet orbits the secondary member every 37.9 days at a distance of 0.139 AU, so it's likely tidally locked if it has a circular orbit (or in spin resonance like Mercury if it has an elliptical orbit).
Based on the star's luminosity and the planet's distance from the star, it receives a similar, but slightly higher amount of starlight as Mars receives compared to Earth (Flux of 0.47 vs 0.43).
The planet isn't known to transit, so the planet was found with radial velocity, with an estimated mass of 3.4 Earths. Unlike other recently found exoplanets in the habitable zone, with masses between 5-7 Earth masses (Like GJ 887d, GJ 3998d, 55 Cnc Bc), this is a relatively lower-mass Super-Earth. So it may be more likely to be rocky, though without a radius to figure out the density and bulk composition, that's unknown.
A radius of between 1.6-1.7 Earth's would give the planet a density similar to Mars (71%) or moderately less than Earth (83%), with a surface gravity 17-32% higher than Earth's.
#space
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