{"id":224410,"date":"2026-01-09T04:19:11","date_gmt":"2026-01-09T04:19:11","guid":{"rendered":"https:\/\/www.newsbeep.com\/nz\/224410\/"},"modified":"2026-01-09T04:19:11","modified_gmt":"2026-01-09T04:19:11","slug":"animal-life-unlikely-around-a-third-of-stars-in-the-galaxy-study-says","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/nz\/224410\/","title":{"rendered":"Animal life unlikely around a third of stars in the galaxy, study says"},"content":{"rendered":"

\t\t\tBack to Article List\t\t<\/p>\n

\n\t\t\t\tWhile late M-stars are the easiest places to find Earth-sized planets, a new study suggests they are biological dead ends where animal life may never find enough fuel to evolve.\t\t\t<\/p>\n

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\n\t\t\t\t\t\tThis illustration depicts the TRAPPIST-1 system from the vantage point of TRAPPIST-1f, showcasing seven Earth-like planets orbiting the late M-star TRAPPIST-1. According to a new study, stars like TRAPPIST-1 cannot support animal life. Credit: NASA\t\t\t\t\t<\/p>\n

A recent study suggests that late M-stars, despite their abundance in the galaxy and potential for hosting detectable Earth-like planets, are unlikely to support the emergence of complex animal life.
\nThis limitation stems from a fundamental mismatch between the stellar emission spectrum of late M-stars and the specific Photosynthetically Active Radiation (PAR, 400-700 nm) required for oxygenic photosynthesis, a critical process for atmospheric oxygen accumulation.
\nSimulations indicate that key biological events on Earth, such as the Great Oxidation Event and the Cambrian Explosion, would require timescales far exceeding the expected lifespan of planets orbiting late M-stars due to insufficient PAR.
\nConsequently, ecosystems on such planets would likely be dominated by organisms utilizing non-oxygenic photosynthesis, which can thrive on the abundant longer-wavelength light, thus precluding the widespread oxygen accumulation necessary for complex, animal metabolisms.<\/p>\n

Humans are captivated by the idea of finding life elsewhere in the universe \u2013 and even more by the idea that life, if found, might resemble the complex, animal life here on Earth. One of the easiest places to look for Earth-like planets that could potentially be home to animal life is in the orbits of M-stars, the most prevalent stars in our galaxy. However, according to a new study<\/a> posted to the ArXiv preprint server, a specific subset of these \u2014 the smallest and coolest known as late M-stars \u2014 are not capable of developing animal life.<\/p>\n

The problem, as Bill Welsh, astronomer at San Diego State University and study co-author, explained in a Jan. 7 press conference<\/a> at the 247th meeting of the American Astronomical Society, is a fundamental mismatch between the light these stars emit and the light animal life needs to produce oxygen. If the study\u2019s findings are true, the hunt for extraterrestrial animal life just got a lot harder, as late M-stars yield the most detectable Earth-like planets and make up 35 percent of all stars in the galaxy.<\/p>\n

Welsh and Joseph Soliz, study co-author, conducted a deceptively simple thought experiment. Instead of guessing what the alien biology of a world orbiting TRAPPIST-1 might be like, they asked a different, yet related question: \u201cWhat would happen if we put Earth in orbit around TRAPPIST-1?\u201d<\/p>\n

On Earth, the \u201cBig Bang of biology,\u201d as Welsh called it, was the Cambrian Explosion, a flood of complex animal life that happened about 500 million years ago. That explosion was only possible because of a long build-up of oxygen known as the \u201cGreat Oxidation Event\u201d (GOE) \u2014 the critical period roughly 2.3 billion years ago when oxygen first began to accumulate in Earth\u2019s atmosphere. This process started 2.5 billion years before the GOE with the evolution of oxygenic photosynthesis, which began releasing an increased amount of oxygen into Earth\u2019s atmosphere.<\/p>\n

Oxygen is the best fuel source for complex, animal life. Organisms with aerobic (oxygen-based) metabolisms generate energy far more efficiently than organisms with anaerobic metabolisms.\u201cOxygen is a very reactive molecule,\u201d Welsh explained. \u201cOxygen provides roughly a factor of 16 times more energy if you use oxygen in your metabolism than if you don\u2019t,\u201d he continued. This efficiency creates an abundance of spare energy that a lifeform can use to develop \u201cshells and appendages and all kinds of things that animals need.\u201d Welsh said. Without oxygen, scientists believe life is limited to what Welsh described as \u201csmall sub-centimeter type life.\u201d<\/p>\n

But oxygenic photosynthesis is also a picky eater. It requires Photosynthetically Active Radiation (PAR) \u2014 light in the 400- to 700-nanometer range. On Earth, our Sun provides a feast of these photons. Around a late M-star like TRAPPIST-1, however, it\u2019s more famine than feast. TRAPPIST-1 provides hardly any photons in this range. Instead, the star\u2019s energy is focused almost entirely above the 800-nanometer range.<\/p>\n

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This graph compares the amount and wavelength of light reaching modern Earth, ancient Earth, and the exoplanet TRAPPIST-1e. The green shaded area marks the specific light ranges required for oxygenic photosynthesis, and the red shaded area marks non-oxygen-producing photosynthesis. Credit: Soliz, J. J., & Welsh, W. F. (2026). https:\/\/arxiv.org\/abs\/2601.02548v1<\/p>\n

In the dim, red glow of TRAPPIST-1, a hypothetical Earth would receive less than one percent of the PAR photons it gets from our Sun. According to the study, the GOE that took 700 million years on Earth would take 63 billion years on an Earth orbiting TRAPPIST-1. And a Cambrian Explosion would take a staggering 235 billion years.<\/p>\n

\u201cWhat happens 100 billion years from now is a whole heck of a lot of speculation,\u201d Welsh said at the press conference. \u201cWe\u2019re limited to the Big Bang and in that time scale, we don\u2019t expect such planets to harbor life.\u201d<\/p>\n

But there is a second, perhaps more decisive blow to our hopes for alien neighbors. While oxygen-producers are starved for light on late M-stars, another group of organisms is enjoying a free lunch. Non-oxygenic photosynthesis \u2014 the kind used by less complex organisms \u2014 is far less picky. It can harvest the photons that M-stars produce in abundance.<\/p>\n

\u201cNon-oxygenic microbes will have a huge advantage,\u201d Welsh said at the press conference. \u201cThey\u2019re probably going to dominate the ecosystem.\u201d<\/p>\n

\u201cWe expect that there will be life on these stars for sure, but it might look like \u2026 purple bacteria living in a sulfur pool, just scratching out an existence,\u201d Welsh tells Astronomy. Without oxygen, he explains, it is unlikely we will ever find anything advanced enough to talk back. \u201cIt\u2019s kind of a bummer because we\u2019re talking about something like 35 percent of all stars in the galaxy.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"Back to Article List While late M-stars are the easiest places to find Earth-sized planets, a new study…\n","protected":false},"author":2,"featured_media":224411,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[134326,21035,12487,111,139,69,147],"class_list":{"0":"post-224410","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-alien-life","9":"tag-astrobiology","10":"tag-exoplanets","11":"tag-new-zealand","12":"tag-newzealand","13":"tag-nz","14":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/224410","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=224410"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/224410\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/224411"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=224410"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=224410"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=224410"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}