AAS 197, January 2001
Session 44. Observations and Analysis of Stellar Atmospheres
Display, Tuesday, January 9, 2001, 9:30am-7:00pm, Exhibit Hall

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[44.06] Mu Leo and NGC 6791: A Statistical Appraisal of Metallicities

B. J. Taylor (Brigham Young University)

Recently, Smith & Ruck (2000, A&A 356, 570) have published a new high-dispersion analysis of \mu Leo. Their result is +0.29 ±0.03 dex, and they conclude that it is superior to a counterpart from Castro et al. (1996, AJ 111, 2439). Smith & Ruck also consider a statistical analysis by Taylor (1999, A&A 344, 655) of 15 published \mu Leo metallicities. Taylor found that the \mu Leo metallicity is not known to exceed +0.2 dex at 95% confidence. Smith & Ruck maintain that Taylor's deduction is no longer applicable.

Taylor's analysis has now been updated to include data from Smith & Ruck and Takeda et al. (1998, PASJ 50, 97). The results of Taylor's analysis are essentially unchanged. The mean value of [Fe/H] for \mu Leo is now ~+0.23 ± 0.025 dex.

Peterson & Green (1998, BAAS 30, 897) have noted that the spectrum of \mu Leo resembles those of red horizontal-branch stars in NGC 6791. This similarity is appraised by applying statistical analysis to other published results. It is found that the low-resolution metallicities of Friel & Janes (1993, A&A 267, 75) for hot and cool giants in NGC 6791 do not differ at 95% overall confidence. Moreover, if E(B-V) ~0.15 mag for NGC 6791, the collected Friel-Janes results do not differ at 95% confidence from high-disperson counterparts for the star 2-17 (Peterson & Green 1998, ApJ 502, L39). At present, collected high-dispersion and low-resolution results permit cluster metallicities in the range 0.2-0.5 dex. A color-magnitude analysis by Chaboyer et al. (1999, AJ 117, 1360) does not narrow this range because it does not satisfy statistical norms. It appears that the recent conclusion that the cluster metallicity is +0.4 dex is prematurely decisive.

This research has been supported by the BYU College of Physical and Mathematical Sciences.

The author(s) of this abstract have provided an email address for comments about the abstract: taylorb@physc3.byu.edu

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