doi.org/10.1016/j.xinn.2026.101265
Credibility: 989
#Stellar Flare
The search for life beyond Earth has always focused on planets orbiting stars similar to our Sun, known as G-type stars
However, in recent years, scientists have begun to look more closely at lower-mass stars, called K-type and M-type stars. These stars are smaller, cooler, and live much longer than the Sun – while the Sun has a lifespan of about 4.5 billion years, K-type stars can last from 15 to 70 billion years, and M-type stars between 100 billion and up to 14 trillion years. Furthermore, they represent about 70% of all stars in the Milky Way, making them very interesting targets for the search for habitable exoplanets.
The habitable zone is the region around a star where conditions allow for the existence of liquid water on the surface of a planet. In the case of smaller stars, this zone (called the liquid water habitable zone) is much closer to the star than in our Solar System. But there is another important concept: the ultraviolet (UV) habitable zone, which considers ultraviolet radiation capable of favoring chemical reactions that can give rise to life, such as the formation of RNA precursors – the basic building blocks of this molecule essential for life as we know it.
A new study by Chinese researchers, published in the journal The Innovation, has made an important contribution by refining the definition of this UV zone. Using detailed models and calculations, the team analyzed how stellar eruptions – called flares – can influence this region. These explosions on the surface of stars release a large amount of energy and UV radiation, which could expand or adjust the boundaries of the zone where prebiotic chemistry (the first steps towards life) becomes more likely.Scientists applied their models to nine confirmed or candidate exoplanets orbiting K- and M-type stars. These include Kepler-1540 b (a Neptune-like planet), KOI-7703.01, KOI-8047.01, Kepler-155 c, KOI-5879.01, Kepler-1512 b, Kepler-438 b, KOI-7706.01, and KOI-8012.01. Most of these worlds are rocky, making them more promising for harboring Earth-like conditions.
The results showed that around low-mass stars, the habitable zones of liquid water and UV radiation can overlap. This means that, at certain distances, a planet could simultaneously have both possible liquid water and sufficient UV radiation to stimulate chemical reactions important for the emergence of life. Of the nine planets studied, three – KOI-8012.01, KOI-8047.01, and KOI-7703.01 – orbit precisely within this overlapping region, making them particularly interesting candidates.
The researchers emphasize that further observations are still needed to confirm the actual habitability of some of these planets, such as Kepler-1540 b, Kepler-438 b, and Kepler-155 c, especially to better understand the temperatures on their surfaces. They also note that assessing the habitability of individual planets remains a challenge, both from an astrobiological and observational point of view. Even so, cataloging planets that fit into different types of habitable zones helps to better understand where life is most likely to arise.A classic example of an M-type star system is TRAPPIST-1, which has seven rocky planets orbiting very close to its star, with periods between 1 and 12 days. Three of them are within the traditional habitable zone, but the system presents challenges: the planets are likely tidally locked (always showing the same face to the star), and the star is quite active, emitting flares and intense radiation. Therefore, the possible habitability of these worlds still raises many questions.
Overall, the study reinforces that stellar flares are not only a problem for life – they can also be allies, providing the UV radiation necessary for essential chemical processes on planets around smaller, longer-lived stars. As new observations and models are developed, scientists hope to further refine these concepts and more accurately identify the worlds that deserve special attention in the search for extraterrestrial life.
Science advances step by step, and each new study like this helps us better understand the conditions that make a planet truly habitable. The future of exoplanet discoveries around small stars promises to be fascinating. (approximately 3,450 characters including spaces)
Published in 04/23/2026 05h27
Text adapted by AI (Grok) and translated via Google API in the English version. Images from public image libraries or credits in the caption. Information about DOI, author and institution can be found in the body of the article.
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