Probing Abundance Variations Among Multiple Stellar Populations in the Metal-poor Globular Cluster NGC 2298 Using Gemini-South/GHOST
Studying the abundances in metal-poor globular clusters is crucial for understanding the formation of the Galaxy and the nucleosynthesis processes in the early Universe. We observed 13 red-giant stars from the metal-poor globular cluster NGC 2298 using the newly commissioned GHOST spectrograph at Ge...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-3881/add52a |
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| author | Avrajit Bandyopadhyay Rana Ezzeddine Vinicius M. Placco Anna Frebel David S Aguado Ian U. Roederer |
| author_facet | Avrajit Bandyopadhyay Rana Ezzeddine Vinicius M. Placco Anna Frebel David S Aguado Ian U. Roederer |
| author_sort | Avrajit Bandyopadhyay |
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| description | Studying the abundances in metal-poor globular clusters is crucial for understanding the formation of the Galaxy and the nucleosynthesis processes in the early Universe. We observed 13 red-giant stars from the metal-poor globular cluster NGC 2298 using the newly commissioned GHOST spectrograph at Gemini South. We derived stellar parameters and abundances for 36 species across 32 elements, including 16 neutron-capture elements. We find that the stars exhibit chemical anomalies among the light elements, allowing us to classify them into first generation (eight stars) and second generation (five stars). We derive a mean cluster metallicity of [Fe/H] = −1.98 ± 0.10 with no significant variation among cluster members. Most α - and Fe-peak elements display low star-to-star abundance dispersion, with notable exceptions for Sc, Ni, and Zn for which the dispersions in Sc vary significantly between stars from different generations to 2 σ levels. Similarly, among the neutron-capture elements, we observed considerable differences in dispersion for Sr and Eu among the first and second generation stars to 2 σ levels. We also confirm an intrinsic scatter beyond observational uncertainties for several elements using a maximum likelihood approach among stars from different generations. Additionally, we note an increase in [Sr/Eu] and [Ba/Eu] with [Mg/Fe] in first-generation stars indicating correlations between the productions of light r process and Mg. We find the universal r -process pattern, but with larger dispersions in the main r process than the limited- r elements. These differences in abundance dispersion, among first- and second-generation stars in NGC 2298, suggest complex and inhomogeneous early chemical enrichment processes, driven by contributions from multiple nucleosynthetic events, including massive stars and rare r -process events. |
| format | Article |
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| issn | 1538-3881 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astronomical Journal |
| spelling | doaj-art-7bbf277532d34fad96bc49e0b84d31b62025-08-20T02:07:56ZengIOP PublishingThe Astronomical Journal1538-38812025-01-0117013710.3847/1538-3881/add52aProbing Abundance Variations Among Multiple Stellar Populations in the Metal-poor Globular Cluster NGC 2298 Using Gemini-South/GHOSTAvrajit Bandyopadhyay0https://orcid.org/0000-0002-8304-5444Rana Ezzeddine1https://orcid.org/0000-0002-8504-8470Vinicius M. Placco2https://orcid.org/0000-0003-4479-1265Anna Frebel3https://orcid.org/0000-0002-2139-7145David S Aguado4https://orcid.org/0000-0001-5200-3973Ian U. Roederer5https://orcid.org/0000-0001-5107-8930Department of Astronomy, University of Florida , Bryant Space Science Center, Gainesville, FL 32611, USA ; abandyopadhyay@ufl.edu; Joint Institute for Nuclear Astrophysics—Center for Evolution of the Elements , USADepartment of Astronomy, University of Florida , Bryant Space Science Center, Gainesville, FL 32611, USA ; abandyopadhyay@ufl.edu; Joint Institute for Nuclear Astrophysics—Center for Evolution of the Elements , USAJoint Institute for Nuclear Astrophysics—Center for Evolution of the Elements , USA; NSF NOIRLab , Tucson, AZ 85719, USAJoint Institute for Nuclear Astrophysics—Center for Evolution of the Elements , USA; Department of Physics & Kavli Institute for Astrophysics and Space Research , Massachusetts Institute of Technology, Cambridge, MA 02139, USAInstituto de Astrofísica de Canarias , Vía Láctea, 38205 La Laguna, Tenerife, Spain; Universidad de La Laguna , Departamento de Astrofísica, E-38206 La Laguna, Tenerife, SpainJoint Institute for Nuclear Astrophysics—Center for Evolution of the Elements , USA; Department of Physics, North Carolina State University , Raleigh, NC 27695, USAStudying the abundances in metal-poor globular clusters is crucial for understanding the formation of the Galaxy and the nucleosynthesis processes in the early Universe. We observed 13 red-giant stars from the metal-poor globular cluster NGC 2298 using the newly commissioned GHOST spectrograph at Gemini South. We derived stellar parameters and abundances for 36 species across 32 elements, including 16 neutron-capture elements. We find that the stars exhibit chemical anomalies among the light elements, allowing us to classify them into first generation (eight stars) and second generation (five stars). We derive a mean cluster metallicity of [Fe/H] = −1.98 ± 0.10 with no significant variation among cluster members. Most α - and Fe-peak elements display low star-to-star abundance dispersion, with notable exceptions for Sc, Ni, and Zn for which the dispersions in Sc vary significantly between stars from different generations to 2 σ levels. Similarly, among the neutron-capture elements, we observed considerable differences in dispersion for Sr and Eu among the first and second generation stars to 2 σ levels. We also confirm an intrinsic scatter beyond observational uncertainties for several elements using a maximum likelihood approach among stars from different generations. Additionally, we note an increase in [Sr/Eu] and [Ba/Eu] with [Mg/Fe] in first-generation stars indicating correlations between the productions of light r process and Mg. We find the universal r -process pattern, but with larger dispersions in the main r process than the limited- r elements. These differences in abundance dispersion, among first- and second-generation stars in NGC 2298, suggest complex and inhomogeneous early chemical enrichment processes, driven by contributions from multiple nucleosynthetic events, including massive stars and rare r -process events.https://doi.org/10.3847/1538-3881/add52aStellar abundancesChemical abundancesGlobular star clustersStellar nucleosynthesisChemically peculiar starsPopulation II stars |
| spellingShingle | Avrajit Bandyopadhyay Rana Ezzeddine Vinicius M. Placco Anna Frebel David S Aguado Ian U. Roederer Probing Abundance Variations Among Multiple Stellar Populations in the Metal-poor Globular Cluster NGC 2298 Using Gemini-South/GHOST The Astronomical Journal Stellar abundances Chemical abundances Globular star clusters Stellar nucleosynthesis Chemically peculiar stars Population II stars |
| title | Probing Abundance Variations Among Multiple Stellar Populations in the Metal-poor Globular Cluster NGC 2298 Using Gemini-South/GHOST |
| title_full | Probing Abundance Variations Among Multiple Stellar Populations in the Metal-poor Globular Cluster NGC 2298 Using Gemini-South/GHOST |
| title_fullStr | Probing Abundance Variations Among Multiple Stellar Populations in the Metal-poor Globular Cluster NGC 2298 Using Gemini-South/GHOST |
| title_full_unstemmed | Probing Abundance Variations Among Multiple Stellar Populations in the Metal-poor Globular Cluster NGC 2298 Using Gemini-South/GHOST |
| title_short | Probing Abundance Variations Among Multiple Stellar Populations in the Metal-poor Globular Cluster NGC 2298 Using Gemini-South/GHOST |
| title_sort | probing abundance variations among multiple stellar populations in the metal poor globular cluster ngc 2298 using gemini south ghost |
| topic | Stellar abundances Chemical abundances Globular star clusters Stellar nucleosynthesis Chemically peculiar stars Population II stars |
| url | https://doi.org/10.3847/1538-3881/add52a |
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