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Dr. Galin Borisov from the Institute of Astronomy at BAS<\/em> has<\/em> participated in the observations <\/em>of<\/em> an international team of astronomers with the 2<\/em>-meter<\/em> telescope of NAO Rozhen.<\/em><\/p>\n Astronomers have discovered that the interstellar comet 3I\/ATLAS (C\/2025 N1)<\/strong> reflects sunlight in a completely new way. Using some of the most powerful telescopes in the world – the Very Large Telescope (ESO)<\/strong> in Chile, the Nordic Optical Telescope (ORM)<\/strong> in Las Palmas (Spain) and the 2-meter telescope at NAO-Rozhen,<\/strong> an international team has found that the comet’s dust exhibits the largest negative polarization<\/strong> ever observed in a comet or asteroid – a discovery that could change our current ideas about small bodies coming from other star systems.<\/p>\n The results, published in The Astrophysical Journal Letters,<\/em> show that the dust of 3I\/ATLAS is a mixture of dark and icy particles<\/strong> similar to those in distant trans-Neptunian objects. Discovered in 2025, 3I\/ATLAS is only the third known interstellar object<\/strong> after 1I\/\u02bbOumuamua and 2I\/Borisov.<\/p>\n Researchers believe this comet may represent an entirely new class of interstellar bodies<\/strong> that reveal how planetary systems form and evolve in other parts of the Galaxy. Upcoming observations around and beyond perihelion will confirm these extraordinary results.<\/p>\n Scientists have observed how sunlight reflected off the comet’s dust and ice creates an unusually strong \u201c<\/strong>negative polarization<\/strong>\u201d<\/strong> signal. \u201cThe polarization signature of 3I\/ATLAS is unlike anything we have seen before,\u201d Dr. Zuri Gray of the University of Helsinki,<\/strong> lead author of the study says. \u201cIt shows a deep and narrow negative polarization – stronger than that of any known comet – suggesting that its dust and ice have completely unknown properties.“<\/p>\n A mysterious messenger from another star system?<\/strong><\/p>\n 3I\/ATLAS is only the third interstellar object<\/strong> discovered so far – after 1I\/\u02bbOumuamua (2017) and 2I\/Borisov (2019). Unlike its predecessors, which had resembled an asteroid and a regular comet, 3I\/ATLAS appears to be a completely new type of interstellar object.<\/strong><\/p>\n Polarimetric data show that light reflected by 3I\/ATLAS is highly polarized in a direction parallel to the scattering plane, <\/strong>a phenomenon known as \u201c<\/strong>negative polarization<\/strong>\u201d<\/strong>.<\/strong> The measured value reaches 2.7% at a phase angle of only 7\u00b0,<\/strong> with an inverse angle of 17\u00b0<\/strong> – a combination not seen in other objects in the Solar system.<\/p>\n Traces of water and unusual dust<\/strong><\/p>\n Spectroscopic observations by other teams have already shown that 3I\/ATLAS has a reddish hue<\/strong> and contains water and carbon dioxide<\/strong> even at large distances from the Sun. The new polarimetric data confirm this and lead to the suggestion that the comet’s dust is a mixture of dark and icy grains<\/strong> similar to those found on distant trans-Neptunian objects.<\/strong><\/p>\n \u201cThis object seems to combine properties of icy bodies from the outer Solar system and of completely alien material from another star,\u201d Dr<\/strong>.<\/strong> Stefano Bagnulo<\/strong> from the Armagh Observatory<\/strong> (UK) explains. \u201cIts characteristics call into question our models for the composition of comet dust.\u201d<\/p>\n A look at galactic diversity<\/strong><\/p>\n Since interstellar visitors like 3I\/ATLAS only pass through our system once, astronomers have limited time to make observations. According to the team, this discovery shows that the diversity of interstellar bodies is much greater<\/strong> than previously thought.<\/p>\n \u201c3I\/ATLAS pushes the boundaries of our knowledge of interstellar objects,\u201d Dr<\/strong>.<\/strong> Galin Borisov from the Institute of Astronomy with the National Astronomical Observatory at BAS<\/strong> says. \u201cIt may represent an entirely new class of small bodies formed under different conditions in other planetary systems.\u201d<\/p>\n Next steps<\/strong><\/p>\n The team will continue observations of 3I\/ATLAS as it approaches the Sun. It is hoped that the new data will help clarify how its coma evolves and whether the unusual polarization behavior persists over time.<\/p>\n The Bulgarian contribution is supported by project No. K\u03a0-06-H88\/5 (December 2024) \u201cPhysical properties and chemical composition of asteroids and comets – a key to deepen knowledge of the origin and evolution of the Solar system\u201d, funded by the Bulgarian National Science Fund. NAO Rozhen is a complex of the National Roadmap for Research Infrastructure 2020-2027 (RACIO project), financially coordinated by the Ministry of Education and Science of the Republic of Bulgaria.<\/p>\n \u00a0[\/fusion_text][\/fusion_builder_column][\/fusion_builder_row][\/fusion_builder_container]<\/p>\n","protected":false},"excerpt":{"rendered":" Dr. Galin Borisov from the Institute of Astronomy at BAS has participated in the observations of an international team of astronomers with the 2-meter telescope of NAO Rozhen. Astronomers have discovered that the interstellar comet 3I\/ATLAS (C\/2025 N1) reflects sunlight in a completely new way. Using some of the most powerful telescopes in the world – the Very Large Telescope (ESO) in Chile, the Nordic Optical Telescope (ORM) in Las Palmas (Spain) and the 2-meter telescope at NAO-Rozhen, an international team has found that the comet’s dust exhibits the largest negative polarization ever observed in a comet or asteroid – a discovery that could change our current ideas about small bodies coming from other star systems. The results, published in The Astrophysical Journal […]<\/a><\/p>\n","protected":false},"author":15,"featured_media":59597,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1479],"tags":[],"_links":{"self":[{"href":"https:\/\/www.bas.bg\/index.php?rest_route=\/wp\/v2\/posts\/59610"}],"collection":[{"href":"https:\/\/www.bas.bg\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bas.bg\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bas.bg\/index.php?rest_route=\/wp\/v2\/users\/15"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bas.bg\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=59610"}],"version-history":[{"count":3,"href":"https:\/\/www.bas.bg\/index.php?rest_route=\/wp\/v2\/posts\/59610\/revisions"}],"predecessor-version":[{"id":59616,"href":"https:\/\/www.bas.bg\/index.php?rest_route=\/wp\/v2\/posts\/59610\/revisions\/59616"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bas.bg\/index.php?rest_route=\/wp\/v2\/media\/59597"}],"wp:attachment":[{"href":"https:\/\/www.bas.bg\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=59610"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bas.bg\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=59610"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bas.bg\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=59610"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}<\/a><\/p>\n