{"id":38772,"date":"2025-07-22T09:30:27","date_gmt":"2025-07-22T07:30:27","guid":{"rendered":"https:\/\/karmaka.de\/?p=38772"},"modified":"2025-07-22T09:30:28","modified_gmt":"2025-07-22T07:30:28","slug":"spectroscopic-characterization-of-interstellar-object-3i-atlas-water-ice-in-the-coma","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=38772","title":{"rendered":"Spectroscopic Characterization of Interstellar Object 3I\/ATLAS: Water Ice in the Coma<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Bin Yang, Karen J. Meech, Michael Connelley, Jacqueline V. Keane<\/p>\n\n\n\n<p>submitted to ApJL<\/p>\n\n\n\n<p><a href=\"https:\/\/arxiv.org\/pdf\/2507.14916\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;We present optical and near-infrared spectroscopy of the interstellar object 3I\/ATLAS, obtained with Gemini-S\/GMOS and NASA IRTF\/SpeX on 2025 July 5 and July 14. The optical spectrum shows a red slope of approximately 10% per 1000 angstroms between 0.5 and 0.8 microns, closely resembling that of typical D-type asteroids. At longer wavelengths, the near-infrared spectrum flattens significantly to approximately 3% per 1000 angstroms from 0.9 to 1.5 microns, consistent with the spectral behavior of large water ice grains in the coma. Spectral modeling with an areal mixture of 70% Tagish Lake meteorite and 30% 10-micron-sized water ice successfully reproduces both the overall continuum and the broad absorption feature near 2.0 microns. The 1.5-micron water ice band, however, is not detected, likely due to the limited signal-to-noise of the IRTF data and dilution by refractory materials. The ~30% ice fraction should be interpreted as an approximate, order-of-magnitude estimate of the coma composition. The agreement between the GMOS and SpeX spectra, taken nine days apart, suggests short-term stability in the coma&#8217;s optical properties. Our observations reveal that 3I\/ATLAS is an active interstellar comet containing abundant water ice, with a dust composition more similar to D-type asteroids than to ultrared trans-Neptunian objects.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Bin Yang, Karen J. Meech, Michael Connelley, Jacqueline V. Keane submitted to ApJL PDF (OPEN ACCESS) &#8220;We present optical and near-infrared spectroscopy of the interstellar object 3I\/ATLAS, obtained with Gemini-S\/GMOS and NASA IRTF\/SpeX on 2025&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[179,3424,130,81],"tags":[6913,6919,1870,2859,5006,6033,3137,6259,2018],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/38772"}],"collection":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=38772"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/38772\/revisions"}],"predecessor-version":[{"id":38773,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/38772\/revisions\/38773"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=38772"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=38772"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=38772"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}