NOAO >   Observing Info >   Approved Programs >   2017B-0129

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Program Information for 2017B-0129


PI: Ricardo Salinas, Gemini Observatory, rsalinas@gemini.edu
Address: Gemini Observatory, Colina El Pino s/n, La Serena Chile

CoI: Carolina Salgado, Australian National U.
CoI: Gary Da Costa, Australian National U.

Title: Constraining the origin of globular cluster abundance anomalies with SMC intermediate-age clusters

Abstract: Understanding the origin of the observationally well-established abundance anomalies in globular cluster stars is a major unsolved problem in stellar populations. Crucial to its solution is discovering whether the anomalies are restricted solely to clusters that formed at the earliest epochs, or if they occur in younger but still massive star clusters. The SMC is the only nearby system hosting massive star clusters with ages between 6 and 11 Gyr, making it the ideal location to explore this question. We have obtained observations with VLT/FORS2 to investigate the distribution of CN and CH-band strengths in red giants in three massive SMC clusters with ages in this interval, seeking the anti-correlated bimodal band strength distributions characteristic of the abundance anomalies in Galactic globular clusters. However, because of possible envelope mixing on the RGB, a CN-CH anti-correlation is not sufficient in itself to indicate the presence of abundance anomalies. Here we seek GMOS-S time to provide crucial additional information by observing the SMC cluster stars at the sodium D-lines. If a positive Na, CN correlation is observed it will unambiguously establish the existence of the abundance anomaly phenomenom in these younger objects. If no Na abundance range is found, then it will strongly suggest that the abundance anomaly phenomenon is restricted to the formation of massive clusters at the earliest times, providing for the first time a definitive context for further investigations. DDT time provided usable data for NGC 339 (2 masks) and Lindsay 1 (1 mask). Here we seek time to complete the project: Lindsay 1(1 mask) and Kron 3(2 masks).

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2017B):  GEM-SQ/GMOSS -- 4.9hrs band 2 (GS-2017B-Q-57)


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NOAO >   Observing Info >   Approved Programs >   2017B-0129

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