{"id":9082,"date":"2024-01-11T11:54:13","date_gmt":"2024-01-11T16:54:13","guid":{"rendered":"https:\/\/spaceandplanetarynewswire.com\/?p=9082"},"modified":"2024-01-11T11:54:13","modified_gmt":"2024-01-11T16:54:13","slug":"stellar-paternity-tests-match-orphaned-stars-to-their-milky-way-origins","status":"publish","type":"post","link":"https:\/\/spaceandplanetarynewswire.com\/?p=9082","title":{"rendered":"\u2018Stellar Paternity Tests\u2019 Match Orphaned Stars to Their Milky Way Origins"},"content":{"rendered":"
Artist’s impression of Gaia mapping the stars of the Milky Way.<\/figcaption><\/figure>\n

In the chaotic environment of open star clusters, strong gravitational interactions between bodies can launch individual stars far outside the cluster, even outside our galaxy, the Milky Way. Now, for the first time researchers have mapped several of those stars, which exist outside the galaxy\u2019s disk, to the clusters of their origin using new data from the European Space Agency\u2019s Gaia Mission.<\/p>\n

Researchers from Lehigh University<\/u><\/a> presented the findings, \u201cStellar Paternity Tests: Matching High-Latitude B Stars to the Open Clusters of Their Birth,\u201d today in a press conference at the 243rd<\/sup> meeting of the American Astronomical Society (AAS) in New Orleans.<\/p>\n

\u201cThrough tracing them back in time to see where they originated, we are able to match 15 of them to the star clusters where they were born,\u201d said M. Virginia (Ginny) McSwain<\/u><\/a>, associate professor of physics, at Lehigh University. \u201cIf we can say with high confidence where some of these stars came from, we will know more about the history of the star clusters in the Milky Way.\u201d<\/p>\n

Most of the stars outside of the thin disk of the Milky Way, which includes the spiral arms with a thicker diameter at the center, are more than eight billion years old, forming early in the galaxy\u2019s history. Given their very old ages, it\u2019s not surprising they have traveled far from their birthplaces.<\/p>\n

Since nearly all of our galaxy\u2019s star formation occurs in the thin disk, hot B-type stars are rarely found outside this region. Yet a small number of these young stars \u2013 estimated at 10- to 100 million years old \u2013 are found at high altitudes above and below the disk, likely ejected from the clusters of their birth in the past few million years.<\/p>\n

\u201cHot stars don\u2019t often venture out of the disk, so when they do, they are noticeably out of place,\u201d said Brandon Schweers, a Lehigh University undergraduate student who provided key research on the project. \u201cThe \u2018parent\u2019 clusters probably ejected most of these B-type stars when close, three- or four- body gravitational interactions flung out a member of the cluster, sending them running away from the plane of the Milky Way.\u201d<\/p>\n

One star studied was flung out with a particularly high speed, so it may have been ejected during a supernova in a close binary star system, said Schweers, a senior studying astrophysics. Stars can even be flung out, only to swing back and be sling-shotted out again.<\/p>\n

While these \u201corphaned\u201d stars have been known for two decades, none had been mapped to their place of origin before, as quality data wasn\u2019t available to trace them to their beginnings. However, with the data from the Gaia Mission, the researchers were able to decipher the stars\u2019 motions in greater precision than was previously available.<\/p>\n

Using Trajectories to Trace Back Time<\/strong><\/p>\n

The Gaia Mission, launched in 2013, aims to survey more than one billion stars in the Milky Way and build a precise three-dimensional map of the galaxy. The data include unprecedented positional measurements for stars and radial velocity measurements for the brightest 150 million objects.<\/p>\n

Based on Gaia data released in 2022, Lehigh researchers traced the kinematic trajectories of 95 high-latitude B stars and about 1,400 known galactic open clusters to identify moments in the past when they may have intersected and an ejection could have occurred.<\/p>\n

\u201cUsing their 3-D positions and 3-D velocities through space, we were able to calculate the trajectories of each cluster and high-latitude star over the past 30 million years,\u201d McSwain said. They used the open-source Python galpy package for galactic dynamics analysis to model the gravitational field of the galaxy at each point.<\/p>\n

Once they identified potential matches, they compared each ejected star\u2019s color and brightness to the Hertzsprung-Russell (H-R) diagram, a color magnitude diagram, for each open cluster. An open cluster generally has thousands of stars of the same age and composition, at the same distance.<\/p>\n

\u201cThe shape of the H-R diagram is mostly dependent on the cluster\u2019s age, so we can tell if the ejected star has a similar age to its potential cluster siblings,\u201d McSwain said. Applying the H-R test narrowed down the list of potential matches further.<\/p>\n

Finally, they analyzed the core densities of each cluster that was a possible match. Clusters with higher density have more of the strong gravitational interactions between members that give them the most potential for ejecting stars.<\/p>\n

Paternity Tests Prove Positive<\/strong><\/p>\n

Combining these tools, the researchers confirmed positive paternity matches for 15 orphaned stars. That galactic genealogical tracing was what gave Schweers the idea for the presentation\u2019s title.<\/p>\n

\u201cWhen I reached the stage of comparing the color and brightness for the potential matches and discarding those that showed a poor correlation in the H-R diagrams, I felt as though I was comparing the \u2018DNA\u2019 of the orphaned stars and their potential siblings,\u201d Schweers said, reminding him of \u201cThe Maury Povich Show.\u201d \u201cI think everyone has heard the saying, \u2018You are not the father\u2019 that came from that show. For many of these clusters, I was essentially telling them they are not the parent of these orphaned stars, so I came up with the name \u2018Stellar Paternity Tests.\u2019\u201d<\/p>\n

Based on their trajectory calculations, the researchers estimate the ejections took place about 5- to 30- million years ago, \u201cflinging abandoned stars across the Milky Way at speeds of 30-220 kilometers\/second (67,000-490,000 miles\/hour) to their present locations,\u201d they wrote. \u201cOur results provide a measure of the ejection age for each orphaned star, providing new insight into the relative importance of dynamical vs. supernovae ejection in young open clusters.\u201d<\/p>\n

While they were able to match a number of the far-flung stars, some couldn\u2019t be traced back to the Milky Way\u2019s disk very plausibly, which may provide evidence for other unusual scenarios, they added. These might include rare star formation in molecular clouds high outside the disk, or they could be relics of past dwarf galaxies that merged with the Milky Way in the past.<\/p>\n

Undergraduate astrophysics student Christopher J. Aviles Bramer, who graduated in 2022, contributed to the research project, which was funded by Lehigh University. The AAS selected the Lehigh University findings to feature in the 2024 meeting\u2019s press conferences.<\/p>\n","protected":false},"excerpt":{"rendered":"

In the chaotic environment of open star clusters, strong gravitational interactions between bodies can launch individual stars far outside the cluster, even outside our galaxy, the Milky Way. Now, for the first time researchers have mapped several of those stars, which exist outside the galaxy\u2019s disk, to the clusters of their origin using new data…<\/p>\n","protected":false},"author":71,"featured_media":9083,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"fifu_image_url":"https:\/\/earimediaprodweb.azurewebsites.net\/Api\/v1\/Multimedia\/f3eb4b3e-f468-4b1c-b32b-70410d96be08\/Rendition\/low-res\/Content\/Public","fifu_image_alt":"\u2018Stellar Paternity Tests\u2019 Match Orphaned Stars to Their Milky Way Origins","footnotes":""},"categories":[207],"tags":[],"class_list":["post-9082","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research"],"_links":{"self":[{"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/posts\/9082","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/users\/71"}],"replies":[{"embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=9082"}],"version-history":[{"count":1,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/posts\/9082\/revisions"}],"predecessor-version":[{"id":9084,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/posts\/9082\/revisions\/9084"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/media\/9083"}],"wp:attachment":[{"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=9082"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=9082"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=9082"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}