{"id":346,"date":"2018-04-24T23:59:02","date_gmt":"2018-04-24T23:59:02","guid":{"rendered":"http:\/\/astro3d.org.au\/?p=346"},"modified":"2020-07-22T11:23:13","modified_gmt":"2020-07-22T01:23:13","slug":"milky-way-stars-kicked-out-by-invading-galaxy","status":"publish","type":"post","link":"https:\/\/astro3d.org.au\/milky-way-stars-kicked-out-by-invading-galaxy\/","title":{"rendered":"Milky way stars kicked out by invading galaxy"},"content":{"rendered":"\n<p>The outer \u201chalo\u201d region of the Milky Way contains the vast majority of the mass of the Galaxy. Unlike the Galaxy\u2019s spiral arms, which contain bright stars, the halo is mostly dark, but they do contain some globular clusters of stars, some of the oldest stars in the Milky Way.<\/p>\n\n\n<p>These stars are generally thought to be ghosts of dwarf galaxies past, long ago torn into shreds after encounters with our more massive galaxy. Now, new research involving ASTRO 3D researcher Dr Luca Casagrande, shows that some of these stars might not be dwarf remnants at all \u2013 they might have come from the Milky Way\u2019s own disk. The question then becomes: how did they travel all the way from the disk out into the stellar halo?<\/p>\n\n\n<p>The researchers found the chemical composition of two outlying groups of stars, A13 and Triangulum-Andromeda, which are about 14,000 light years above and below the plane of the Milky Way, closely matched the stars in our galaxy.<\/p>\n\n\n<p><em>\u201cWe think these stars were evicted through a tidal interaction of the Milky Way and a dwarf galaxy,\u201d<\/em> said Dr Casagrande, an ARC Future Fellow at the ANU Research School of Astronomy and Astrophysics. Tidal interactions between galaxies involve the gravitational field of each galaxy distorting the other \u2013such interactions can change, sometimes dramatically, the form and structure of the galaxies involved.<\/p>\n\n\n<p><em>\u201cThese findings are very exciting, as they indicate that the Milky Way Galaxy\u2019s disk as a whole can oscillate because of tidal interaction and it\u2019s dynamics are significantly more complex than previously thought.\u201d<\/em><\/p>\n\n\n<p>Dr Casagrande measured the temperature of the stars involved in the study, which enabled the team\u2019s analysis of stellar distances and chemical compositions. He used the infrared flux method, a technique regarded as one of the most reliable to measure temperature in stars.<\/p>\n\n\n<p>ANU and research institutions in Germany, the United States, Spain, the United Kingdom and South Korea supported the study, which was led by the Max Planck Institute for Astronomy in Germany. The research was published in <a href=\"https:\/\/www.nature.com\/articles\/nature25490?sf183489611=1\">Nature<\/a>.<\/p>\n\n\n<p>Large galaxy clusters are the most massive structures in the Universe, comprising 10,000\u2019s of galaxies. As predicted by Einstein, their large mass causes them to act as efficient \u201dcosmic telescopes\u201d (called gravitational lenses), amplifying and boosting the size and brightness of distant galaxies which serendipitously lie behind them. The gains can be up to 50x, allowing us to study the processes of galaxy formation in galaxies at a level of detail that would otherwise have to wait a decade.<\/p>\n\n\n<p>ASTRO 3D researchers have been able, for the first time, to look back 11 billion years, to directly witness the formation of the first, primitive spiral arms of a galaxy. Dr Tiantian Yuan and collaborators observed a gravitationally lensed spiral galaxy at redshift z = 2.54.<\/p>\n\n\n<p>It is the most ancient spiral galaxy discovered and the second kinematically confirmed spiral at z &gt; 2.<\/p>\n\n\n<p>The galaxy, known as A1689B11, existing 11 billion years in the past, just 2.6 billion years after the Big Bang. At this time in the Universe formation, spiral galaxies are exceptionally rare and this one is forming stars 20 times faster than galaxies today \u2014 as fast as other young galaxies of similar masses in the early Universe. However, unlike other galaxies of the same epoch, A1689B11 has a very cool and thin disc, rotating with very little turbulence, which has never been seen before at this stage of the Universe.<\/p>\n\n\n<p>The ASTRO 3D researchers used a powerful technique that combines gravitational lensing with the Nearinfrared Integral Field Spectrography (NIFS) on the Gemini North telescope in Hawai\u2019I to verify the vintage and spiral nature of the galaxy.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The outer \u201chalo\u201d region of the Milky Way contains the [&hellip;]<\/p>\n","protected":false},"author":109,"featured_media":281,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[18,2,7],"tags":[],"coauthors":[],"class_list":["post-346","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-galah","category-news","category-science"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v23.8 - 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Expertise in strategic planning, financial and human resource management, and development of education and outreach programs.\",\"sameAs\":[\"https:\/\/www.linkedin.com\/in\/ingrid-mccarthy-0707\",\"https:\/\/x.com\/ingidefygravity\"],\"url\":\"https:\/\/astro3d.org.au\/member\/ingridmccarthy\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Milky way stars kicked out by invading galaxy - ASTRO 3D","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/astro3d.org.au\/milky-way-stars-kicked-out-by-invading-galaxy\/","og_locale":"en_US","og_type":"article","og_title":"Milky way stars kicked out by invading galaxy - ASTRO 3D","og_description":"The outer \u201chalo\u201d region of the Milky Way contains the [&hellip;]","og_url":"https:\/\/astro3d.org.au\/milky-way-stars-kicked-out-by-invading-galaxy\/","og_site_name":"ASTRO 3D","article_published_time":"2018-04-24T23:59:02+00:00","article_modified_time":"2020-07-22T01:23:13+00:00","og_image":[{"width":920,"height":518,"url":"https:\/\/astro3d.org.au\/wp-content\/uploads\/2019\/07\/3D-artists-impression-of-MW_A13-and-Triangulum-Andromeda.jpg","type":"image\/jpeg"}],"author":"Ingrid McCarthy","twitter_card":"summary_large_image","twitter_creator":"@ingidefygravity","twitter_misc":{"Written by":"Ingrid McCarthy","Est. reading time":"3 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/astro3d.org.au\/milky-way-stars-kicked-out-by-invading-galaxy\/","url":"https:\/\/astro3d.org.au\/milky-way-stars-kicked-out-by-invading-galaxy\/","name":"Milky way stars kicked out by invading galaxy - ASTRO 3D","isPartOf":{"@id":"https:\/\/astro3d.org.au\/#website"},"primaryImageOfPage":{"@id":"https:\/\/astro3d.org.au\/milky-way-stars-kicked-out-by-invading-galaxy\/#primaryimage"},"image":{"@id":"https:\/\/astro3d.org.au\/milky-way-stars-kicked-out-by-invading-galaxy\/#primaryimage"},"thumbnailUrl":"https:\/\/astro3d.org.au\/wp-content\/uploads\/2019\/07\/3D-artists-impression-of-MW_A13-and-Triangulum-Andromeda.jpg","datePublished":"2018-04-24T23:59:02+00:00","dateModified":"2020-07-22T01:23:13+00:00","author":{"@id":"https:\/\/astro3d.org.au\/#\/schema\/person\/e70741e6a8b0262812909d3a5c044ea3"},"breadcrumb":{"@id":"https:\/\/astro3d.org.au\/milky-way-stars-kicked-out-by-invading-galaxy\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/astro3d.org.au\/milky-way-stars-kicked-out-by-invading-galaxy\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/astro3d.org.au\/milky-way-stars-kicked-out-by-invading-galaxy\/#primaryimage","url":"https:\/\/astro3d.org.au\/wp-content\/uploads\/2019\/07\/3D-artists-impression-of-MW_A13-and-Triangulum-Andromeda.jpg","contentUrl":"https:\/\/astro3d.org.au\/wp-content\/uploads\/2019\/07\/3D-artists-impression-of-MW_A13-and-Triangulum-Andromeda.jpg","width":920,"height":518},{"@type":"BreadcrumbList","@id":"https:\/\/astro3d.org.au\/milky-way-stars-kicked-out-by-invading-galaxy\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/astro3d.org.au\/"},{"@type":"ListItem","position":2,"name":"Milky way stars kicked out by invading galaxy"}]},{"@type":"WebSite","@id":"https:\/\/astro3d.org.au\/#website","url":"https:\/\/astro3d.org.au\/","name":"ASTRO 3D","description":"Unlocking the Universe - Inspiring the Future","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/astro3d.org.au\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Person","@id":"https:\/\/astro3d.org.au\/#\/schema\/person\/e70741e6a8b0262812909d3a5c044ea3","name":"Ingrid McCarthy","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/astro3d.org.au\/#\/schema\/person\/image\/53153e70ba21b7b09415ce9b2c444760","url":"https:\/\/astro3d.org.au\/wp-content\/uploads\/2020\/10\/ingrid-2020-for-web-e1663898129738-150x150.jpg","contentUrl":"https:\/\/astro3d.org.au\/wp-content\/uploads\/2020\/10\/ingrid-2020-for-web-e1663898129738-150x150.jpg","caption":"Ingrid McCarthy"},"description":"STEM management professional with over 25 years of experience leading science communication, education and resource management teams across government and private sectors. 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