Zirconium, barium, lanthanum, and europium abundances in open clusters
We present an analysis of the s-process elements Zr, Ba, and La and the r-process element Eu in a sample of 50 stars in 19 open clusters. Stellar abundances of each element are based on measures of a minimum of two lines per species via both equivalent width and spectrum synthesis techniques. We inv...
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| Format: | Article |
| Language: | en_US |
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IOP Publishing
2015
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| Online Access: | http://hdl.handle.net/1721.1/92728 https://orcid.org/0000-0001-7727-1640 |
| _version_ | 1826197053175234560 |
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| author | Friel, Eileen D. Jacobson, Heather |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Friel, Eileen D. Jacobson, Heather |
| author_sort | Friel, Eileen D. |
| collection | MIT |
| description | We present an analysis of the s-process elements Zr, Ba, and La and the r-process element Eu in a sample of 50 stars in 19 open clusters. Stellar abundances of each element are based on measures of a minimum of two lines per species via both equivalent width and spectrum synthesis techniques. We investigate cluster mean neutron-capture abundance trends as a function of cluster age and location in the Milky Way disk and compare them to results found in other studies in the literature. We find a statistically significant trend of increasing cluster [Ba/Fe] as a function of decreasing cluster age, in agreement with recent findings for other open cluster samples, supporting the increased importance of low-mass asymptotic giant branch stars to the generation of s-process elements. However, the other s-process elements, [La/Fe] and [Zr/Fe], do not show similar dependences, in contrast to theoretical expectations and the limited observational data from other studies. Conversely, cluster [Eu/Fe] ratios show a slight increase with increasing cluster age, although with marginal statistical significance. Ratios of [s/r]-process abundances, [Ba/Eu] and [La/Eu], however, show more clearly the increasing efficiency of s-process relative to r-process enrichment in open cluster chemical evolution, with significant increases among younger clusters. Last, cluster neutron-capture element abundances appear to be independent of Galactocentric distance. We conclude that a homogeneous analysis of a larger sample of open clusters is needed to resolve the apparent discrepant conclusions between different studies regarding s-process element abundance trends with age to better inform models of galactic chemical evolution. |
| first_indexed | 2024-09-23T10:42:04Z |
| format | Article |
| id | mit-1721.1/92728 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T10:42:04Z |
| publishDate | 2015 |
| publisher | IOP Publishing |
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| spelling | mit-1721.1/927282022-09-30T22:20:32Z Zirconium, barium, lanthanum, and europium abundances in open clusters Friel, Eileen D. Jacobson, Heather Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research Jacobson, Heather We present an analysis of the s-process elements Zr, Ba, and La and the r-process element Eu in a sample of 50 stars in 19 open clusters. Stellar abundances of each element are based on measures of a minimum of two lines per species via both equivalent width and spectrum synthesis techniques. We investigate cluster mean neutron-capture abundance trends as a function of cluster age and location in the Milky Way disk and compare them to results found in other studies in the literature. We find a statistically significant trend of increasing cluster [Ba/Fe] as a function of decreasing cluster age, in agreement with recent findings for other open cluster samples, supporting the increased importance of low-mass asymptotic giant branch stars to the generation of s-process elements. However, the other s-process elements, [La/Fe] and [Zr/Fe], do not show similar dependences, in contrast to theoretical expectations and the limited observational data from other studies. Conversely, cluster [Eu/Fe] ratios show a slight increase with increasing cluster age, although with marginal statistical significance. Ratios of [s/r]-process abundances, [Ba/Eu] and [La/Eu], however, show more clearly the increasing efficiency of s-process relative to r-process enrichment in open cluster chemical evolution, with significant increases among younger clusters. Last, cluster neutron-capture element abundances appear to be independent of Galactocentric distance. We conclude that a homogeneous analysis of a larger sample of open clusters is needed to resolve the apparent discrepant conclusions between different studies regarding s-process element abundance trends with age to better inform models of galactic chemical evolution. National Science Foundation (U.S.). Astronomy and Astrophysics Postdoctoral Fellowship (Award AST-0901919) 2015-01-07T16:29:39Z 2015-01-07T16:29:39Z 2013-03 2013-02 Article http://purl.org/eprint/type/JournalArticle 0004-6256 1538-3881 http://hdl.handle.net/1721.1/92728 Jacobson, Heather R., and Eileen D. Friel. “Zirconium, Barium, Lanthanum, and Europium Abundances in Open Clusters.” The Astronomical Journal 145, no. 4 (March 14, 2013): 107. © 2013 The American Astronomical Society https://orcid.org/0000-0001-7727-1640 en_US http://dx.doi.org/10.1088/0004-6256/145/4/107 Astronomical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf IOP Publishing American Astronomical Society |
| spellingShingle | Friel, Eileen D. Jacobson, Heather Zirconium, barium, lanthanum, and europium abundances in open clusters |
| title | Zirconium, barium, lanthanum, and europium abundances in open clusters |
| title_full | Zirconium, barium, lanthanum, and europium abundances in open clusters |
| title_fullStr | Zirconium, barium, lanthanum, and europium abundances in open clusters |
| title_full_unstemmed | Zirconium, barium, lanthanum, and europium abundances in open clusters |
| title_short | Zirconium, barium, lanthanum, and europium abundances in open clusters |
| title_sort | zirconium barium lanthanum and europium abundances in open clusters |
| url | http://hdl.handle.net/1721.1/92728 https://orcid.org/0000-0001-7727-1640 |
| work_keys_str_mv | AT frieleileend zirconiumbariumlanthanumandeuropiumabundancesinopenclusters AT jacobsonheather zirconiumbariumlanthanumandeuropiumabundancesinopenclusters |