{"id":918922,"date":"2026-07-11T00:16:01","date_gmt":"2026-07-11T05:16:01","guid":{"rendered":"https:\/\/newsycanuse.com\/index.php\/2026\/07\/11\/astronomers-discover-another-galaxy-seemingly-devoid-of-dark-matter\/"},"modified":"2026-07-11T00:16:01","modified_gmt":"2026-07-11T05:16:01","slug":"astronomers-discover-another-galaxy-seemingly-devoid-of-dark-matter","status":"publish","type":"post","link":"https:\/\/newsycanuse.com\/index.php\/2026\/07\/11\/astronomers-discover-another-galaxy-seemingly-devoid-of-dark-matter\/","title":{"rendered":"Astronomers discover another galaxy seemingly devoid of dark matter"},"content":{"rendered":"<div>\n<div>\n<p>A galaxy appears to be missing the invisible substance thought to hold such objects together, further challenging long-held assumptions about how galaxies form<\/p>\n<p>By <a href=\"http:\/\/www.scientificamerican.com\/author\/sam-macdonald\/\" data-click-position=\"authorlink\">Sam Macdonald<\/a> <span>edited by <a href=\"http:\/\/www.scientificamerican.com\/author\/claire-cameron\/\" data-click-position=\"authorlink\">Claire Cameron<\/a><\/span><\/p>\n<\/div>\n<div>\n<figure><img decoding=\"async\" src=\"https:\/\/static.scientificamerican.com\/dam\/asset\/58efc707-e715-4f4e-9370-db2647a31896\/D9.jpg?m=1781706801.592&#038;w=600\" alt=\"A close-up Hubble image of the galaxy DF9 is shown beneath a wider view of the surrounding NGC 1052 region.\"   fetchpriority=\"high\"><figcaption>\n<p>A close-up Hubble image of the galaxy DF9 is shown beneath a wider view of the surrounding NGC 1052 region.<\/p>\n<p>Credit: Keim et al.\/DECaLS\/HST<\/p>\n<\/figcaption><\/figure>\n<\/div>\n<\/div>\n<div data-click-position=\"inline-link\">\n<p class data-block=\"sciam\/paragraph\">NASA calls <a href=\"https:\/\/www.scientificamerican.com\/article\/what-is-dark-matter1\/\">dark matter<\/a> the glue that holds the universe together\u2014but the evidence is mounting that, at least in some galaxies, dark matter isn\u2019t so necessary. A new <a href=\"https:\/\/iopscience.iop.org\/article\/10.3847\/1538-4357\/ae6b8d\">study<\/a> led by astronomers at Yale University has identified a galaxy that appears to contain almost no dark matter at all. This is the third galaxy of its kind to be found\u2014<a href=\"https:\/\/www.scientificamerican.com\/article\/astronomers-boggle-at-a-distant-galaxy-devoid-of-dark-matter\/\">two other galaxies were previously discovered<\/a> to be devoid of the elusive adhesive.<\/p>\n<p class data-block=\"sciam\/paragraph\">This new galaxy, named DF9, was found lurking in the same thin chain of galaxies as the first two, called DF2 and DF4, although it is some 100 times dimmer. Using an instrument called the Keck Cosmic Web Imager, researchers measured the motions of stars within DF9 and used those motions to estimate its mass. The result suggests that this galaxy contains little, if any, dark matter.<\/p>\n<p class data-block=\"sciam\/paragraph\">Dark matter is notoriously difficult to detect because it doesn\u2019t interact with light. We can\u2019t see it directly, but scientists infer its presence from its gravitational effects. The process is a bit like tracking an invisible person by their footprints in the snow. Dark matter leaves \u201cfootprints\u201d in the motions of stars and galaxies, which often move as though they contain far more mass than we can see.<\/p>\n<hr>\n<h2>On supporting science journalism<\/h2>\n<p>If you&#8217;re enjoying this article, consider supporting our award-winning journalism by <a href=\"http:\/\/www.scientificamerican.com\/getsciam\/\">subscribing<\/a>. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.<\/p>\n<hr>\n<p class data-block=\"sciam\/paragraph\">That\u2019s how dark matter was detected in the first place: astronomers noticed that galaxies seemed to be carrying around a great deal of invisible baggage. Many scientists believe it is critical to the fabric of the universe, although some physicists disagree <a href=\"https:\/\/www.scientificamerican.com\/article\/is-dark-matter-real\/\">that it exists at all<\/a>.<\/p>\n<figure data-block=\"contentful\/image\"><iframe data-src=\"https:\/\/www.youtube.com\/embed\/gtFwbxrrCAY\" width=\"1280\" height=\"720\" loading=\"lazy\" allowfullscreen aria-label=\"Video player\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; picture-in-picture; web-share\"><\/iframe><\/figure>\n<p class data-block=\"sciam\/paragraph\">For those who do accept dark matter, galaxies like DF9 present a different puzzle: Why is the dark matter missing? One leading explanation is that these galaxies were forged in violent collisions between two much larger galaxies. In this scenario, the smashups were so violent that ordinary matter separated from dark matter, resulting in these dark-matter-devoid objects.<\/p>\n<p class data-block=\"sciam\/paragraph\">DF9 may be the latest piece of evidence from that ancient cosmic pileup.<\/p>\n<p class data-block=\"sciam\/paragraph\">\u201cAlmost every galaxy in the universe is dominated by dark matter. But DF2, DF4, and now DF9 appear to be extraordinary exceptions,\u201d said Michael Keim, a researcher and lead author of the study, in a <a href=\"https:\/\/keckobservatory.org\/df9\/\">statement<\/a>. \u201cThese findings provide some of the clearest evidence yet that these galaxies formed together in a violent event that separated ordinary matter from dark matter.\u201d<\/p>\n<p class data-block=\"sciam\/paragraph\">The new results could offer clues to the precise nature of what we think of as dark matter, pushing forward a more comprehensive understanding of the cosmos.<\/p>\n<p class data-block=\"sciam\/paragraph\">\u201cThe finding provides compelling evidence that dark matter behaves as a physical substance rather than the effect of an alternative theory of gravity, particularly at the dwarf-galaxy scale where those theories are most heavily debated,\u201d said Pieter van Dokkum, a study co-author and Yale astronomer, in the same statement.<\/p>\n<\/div>\n<section>\n<h2>It\u2019s Time to Stand Up for Science<\/h2>\n<p>If you enjoyed this article, I\u2019d like to ask for your support. <span>Scientific American<\/span> has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.<\/p>\n<p>I\u2019ve been a <span>Scientific American<\/span> subscriber since I was 12 years old, and it helped shape the way I look at the world. <span>SciAm <\/span>always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.<\/p>\n<p>If you <a href=\"http:\/\/www.scientificamerican.com\/getsciam\/\">subscribe to <span>Scientific American<\/span><\/a>, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.<\/p>\n<p>In return, you get essential news, <a href=\"http:\/\/www.scientificamerican.com\/podcasts\/\">captivating podcasts<\/a>, brilliant infographics, <a href=\"http:\/\/www.scientificamerican.com\/newsletters\/\">can&#8217;t-miss newsletters<\/a>, must-watch videos, <a href=\"http:\/\/www.scientificamerican.com\/games\/\">challenging games<\/a>, and the science world&#8217;s best writing and reporting. You can even <a href=\"http:\/\/www.scientificamerican.com\/getsciam\/gift\/\">gift someone a subscription<\/a>.<\/p>\n<p>There has never been a more important time for us to stand up and show why science matters. I hope you\u2019ll support us in that mission.<\/p>\n<\/section>\n<p> Elida Schildgen<br \/><a href=\"https:\/\/www.scientificamerican.com\/article\/astronomers-discover-another-galaxy-seemingly-devoid-of-dark-matter\/\" class=\"button purchase\" rel=\"nofollow noopener\" target=\"_blank\">Read More<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>A galaxy appears to be missing the invisible substance thought to hold such objects together, further challenging long-held assumptions about how galaxies form By Sam Macdonald edited by Claire Cameron A close-up Hubble image of the galaxy DF9 is shown beneath a wider view of the surrounding NGC 1052 region. Credit: Keim et al.\/DECaLS\/HST NASA<\/p>\n","protected":false},"author":1,"featured_media":918923,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22761,4301],"tags":[10920,10865],"class_list":["post-918922","post","type-post","status-publish","format-standard","has-post-thumbnail","category-astronomers","category-discover","tag-astronomers","tag-discover"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/newsycanuse.com\/index.php\/wp-json\/wp\/v2\/posts\/918922","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/newsycanuse.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/newsycanuse.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/newsycanuse.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/newsycanuse.com\/index.php\/wp-json\/wp\/v2\/comments?post=918922"}],"version-history":[{"count":0,"href":"https:\/\/newsycanuse.com\/index.php\/wp-json\/wp\/v2\/posts\/918922\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/newsycanuse.com\/index.php\/wp-json\/wp\/v2\/media\/918923"}],"wp:attachment":[{"href":"https:\/\/newsycanuse.com\/index.php\/wp-json\/wp\/v2\/media?parent=918922"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/newsycanuse.com\/index.php\/wp-json\/wp\/v2\/categories?post=918922"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/newsycanuse.com\/index.php\/wp-json\/wp\/v2\/tags?post=918922"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}