{"id":37291,"date":"2026-04-25T07:40:25","date_gmt":"2026-04-25T01:55:25","guid":{"rendered":"https:\/\/www.revoscience.com\/en\/?p=37291"},"modified":"2026-04-25T07:40:27","modified_gmt":"2026-04-25T01:55:27","slug":"alma-detects-first-semi-heavy-water-in-interstellar-comet-revealing-frigid-origins","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/alma-detects-first-semi-heavy-water-in-interstellar-comet-revealing-frigid-origins\/","title":{"rendered":"ALMA Detects First Semi-Heavy Water in Interstellar Comet, Revealing Frigid Origins"},"content":{"rendered":"\n

SANTIAGO <\/strong>\u2014 Astronomers using the Atacama Large Millimeter\/submillimeter Array (ALMA) in Chile have made the first-ever measurement of deuterated water, or semi-heavy water, in an interstellar object, detecting unusually high levels in comet 3I\/ATLAS.<\/p>\n\n\n\n

The study, led by University of Michigan PhD student Luis E. Salazar Manzano with assistant professor Teresa Paneque-Carre\u00f1o, found that the comet contains at least 30 times more semi-heavy water than comets in our Solar System, offering rare chemical clues to the frigid environment in which its home star system formed.<\/p>\n\n\n\n

\"\"
This artist\u2019s impression compares the semi-heavy water content of the interstellar comet 3I\/ATLAS (left) and Earth (right). Insets illustrate the relative abundance of deuterated water (HDO) molecules, showing that 3I\/ATLAS contains over 30 times more HDO than is found in Earth\u2019s oceans. This elevated ratio suggests the comet formed in an extremely cold environment, very different from the conditions that shaped our Solar System. Credit: NSF\/AUI\/NSF NRAO\/M.Weiss<\/sup><\/em><\/figcaption><\/figure>\n\n\n\n

\u201cOur new observations show that the conditions that led to the formation of our Solar System are much different from how planetary systems evolved in different parts of our Galaxy,\u201d Salazar Manzano said.<\/p>\n\n\n\n

Comets, often described as \u201cdirty snowballs,\u201d preserve frozen records of their birth environments. In Solar System comets, semi-heavy water molecules occur at a ratio of about one in 10,000 compared to ordinary water. In 3I\/ATLAS, the ratio is at least 30 times higher, exceeding levels found in Earth\u2019s oceans.<\/p>\n\n\n\n

Ordinary water itself was below ALMA\u2019s detection threshold, so the team inferred production rates indirectly by modeling methanol emissions. The elevated ratio points to an origin in temperatures below 30 Kelvin (minus 406 degrees Fahrenheit), conditions that enhance deuterium enrichment.<\/p>\n\n\n\n

Paneque-Carre\u00f1o noted ALMA\u2019s unique ability to observe near the Sun, allowing measurements just days after the comet\u2019s closest approach. \u201cMost instruments can\u2019t point toward the Sun, but radio telescopes like ALMA can,\u201d she said.<\/p>\n\n\n\n

Scientists say the findings carry cosmological significance, since hydrogen and deuterium abundances were set during the Big Bang. \u201cEach interstellar comet brings a little bit of its history, its fossils, from elsewhere,\u201d Paneque-Carre\u00f1o added. \u201cWith instruments like ALMA we can begin to understand the conditions of that place and compare them to our own.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

SANTIAGO \u2014 Astronomers using the Atacama Large Millimeter\/submillimeter Array (ALMA) in Chile have made the first-ever measurement of deuterated water, or semi-heavy water, in an interstellar object, detecting unusually high levels in comet 3I\/ATLAS.<\/p>\n","protected":false},"author":2,"featured_media":37292,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[20],"tags":[],"class_list":["post-37291","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-space-news"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet.webp",1500,1000,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-200x200.webp",200,200,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-675x450.webp",675,450,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-768x512.webp",750,500,true],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-1100x733.webp",750,500,true],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet.webp",1500,1000,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet.webp",1500,1000,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-1200x800.webp",1200,800,true],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-870x570.webp",870,570,true],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-600x900.webp",600,900,true],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-600x600.webp",600,600,true],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-760x490.webp",760,490,true],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-550x360.webp",550,360,true],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-95x65.webp",95,65,true],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-640x853.webp",640,853,true],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-96x96.webp",96,96,true],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/04\/interstellar-comet-150x100.webp",150,100,true]},"author_info":{"info":["RevoScience"]},"category_info":"Space\/ AstroPhysics<\/a>","tag_info":"Space\/ AstroPhysics","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/37291","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=37291"}],"version-history":[{"count":2,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/37291\/revisions"}],"predecessor-version":[{"id":37294,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/37291\/revisions\/37294"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/37292"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=37291"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=37291"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=37291"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}