AAS 207th Meeting, 8-12 January 2006
Session 71 (WIYN) Open Clusters and Associations
Poster, Tuesday, 9:20am-6:30pm, January 10, 2006, Exhibit Hall

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[71.10] Self Consistent Isochrones with Flexible Chemistry: The Age, Metallicity, and He Content of NGC 6791

A. Dotter, B. Chaboyer (Dartmouth College), E. Baron (University of Oklahoma), J. W. Ferguson (Wichita State University), J. B. Jensen (Gemini Observatory), A. Sarajedini (University of Florida), T. von Hippel (University of Texas at Austin)

A new database of stellar evolution models, isochrones, and luminosity functions is being created for general use. The database has been designed to cover a wide range of chemical compositions. The stellar evolution models include opacities, equation of state calculations, and initial stellar models that account for each composition in a self consistent manner. To simplify and improve the models, surface boundary conditions, low temperature opacities, and color-effective temperature transformations have all been obtained from the PHOENIX model atmosphere code. As an example of the versatility of the new stellar evolution database, isochrones are compared to near-IR observations of NGC 6791. NGC 6791 is among the oldest open clusters in the Milky Way but, paradoxically, it is also among the most metal rich. The comparison is performed using isochrones with [Fe/H]= +0.2 and +0.4 and initial Helium mass fractions Y=0.27, 0.29, 0.31, and 0.35 in an attempt to constrain the age, metallicity, and He content of this unusual cluster. Additional comparisons of other clusters at different metallicities and in different photometric systems further emphasize the comprehensive nature of the new database. All outputs from this database, including stellar evolutionary tracks, isochrones, and luminosity functions, are available for download at http://stellar.dartmouth.edu/~models/.

If you would like more information about this abstract, please follow the link to http://stellar.dartmouth.edu/~models/. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

The author(s) of this abstract have provided an email address for comments about the abstract: aaron.l.dotter@dartmouth.edu

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