{"id":38698,"date":"2025-07-08T10:43:05","date_gmt":"2025-07-08T08:43:05","guid":{"rendered":"https:\/\/karmaka.de\/?p=38698"},"modified":"2025-07-08T10:43:06","modified_gmt":"2025-07-08T08:43:06","slug":"interstellar-comet-3i-atlas-discovery-and-physical-description","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=38698","title":{"rendered":"Interstellar comet 3I\/ATLAS: discovery and physical description<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Bryce T. Bolin, Matthew Belyakov, Christoffer Fremling, Matthew J. Graham, Candace L. Gray, Carl Ingebretsen, Gracyn Jewett, Mukremin Kilic, Carey M. Lisse, Diana Roderick, Ahmed. M. Abdelaziz, Laura-May Abron, Michael W. Coughlin, Eslam Elhosseiny, Cheng-Han Hsieh, Martin Ma\u0161ek, Mona Molham, Ali Takey, Keith S. Noll, Ian Wong<\/p>\n\n\n\n<p>Preprint 8 July 2025, submitted to MNRAS<\/p>\n\n\n\n<p><a href=\"https:\/\/arxiv.org\/pdf\/2507.05252\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;We describe the physical characteristics of interstellar comet 3I\\ATLAS, discovered on 2025 July 1 by the Asteroid Terrestrial-impact Last Alert System. The comet has eccentricity, \ud835\udc52 \u2243 6.08 and velocity at infinity, v\u221e \u2243 57 km\/s, indicating an interstellar origin. We obtained g, r, i photometry with the Palomar 200-inch Next Generation Palomar Spectrograph on 2025 July 3. We measured colour indices g-r = 0.43\u00b10.02 mag, r-i = 0.16\u00b10.02 mag, and g-i = 0.59\u00b10.03 mag and a spectral slope of 1.3\u00b10.9%\/100 nm. We calculate the dust cross-section within 10,000 km of the comet to be 230.0\u00b15.2 km2, assuming an albedo of 0.10. The FWHM of 3I\\ATLAS&#8217;s detection is \u223c2.2 arcsec as measured in our r-band images and has A(0\u25e6)f\ud835\udf0c of 287.2\u00b12.8 cm. Finally, we use the sunward extent of the coma to constrain the dust ejection speed, finding that \u03bcm-scale to mm-scale particles have \u223c0.01-1 m\/s, implying the comet&#8217;s dust mass-loss rate is \u223c0.1 &#8211; 1.0 kg\/s.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Bryce T. Bolin, Matthew Belyakov, Christoffer Fremling, Matthew J. Graham, Candace L. Gray, Carl Ingebretsen, Gracyn Jewett, Mukremin Kilic, Carey M. Lisse, Diana Roderick, Ahmed. M. Abdelaziz, Laura-May Abron, Michael W. Coughlin, Eslam Elhosseiny, Cheng-Han&#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],"tags":[6913,1870,6033],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/38698"}],"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=38698"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/38698\/revisions"}],"predecessor-version":[{"id":38699,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/38698\/revisions\/38699"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=38698"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=38698"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=38698"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}