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Physics and Astronomy Guy Worthey

Guy Worthey

Research Interests

  • Stellar populations in external galaxies
  • Observational cosmology and galaxy formation
  • Theoretical models of stellar populations

The Dial-a-model page
allows the user to concoct their own population mix and view the results. Based on the Worthey 1994, ApJS, 95, 107 models.

The Lick/IDS system link
gives help (advice and data) for those wanting to measure Lick indices in their own spectra.

Coming soon: The Lick2 index system . . .

Recent papers:

The Observability of Abundance Ratio Effects in Dynamically Hot Stellar Systems, by J. Serven, Guy Worthey, and Michael M. Briley, ApJ, submitted.
Manuscript:, serven.pdf.
Readable version of Tables 2 and 3:, table23.pdf, and plain text version table23.txt.

Related to this paper are the data tables associated with Houdashelt et al. 2002, BAAS 201, 14.05, who computed the same synthetic Lick/IDS indices as Tripicco & Bell 1995, but with (1) the WO97 Balmer indices added, (2) TiO line lists added, and (3) a [C/M] enhancement of only 0.15 dex to avoid the nonlinear effects of having the C/O ratio approach unity. These tables have not been published in a journal, but they are valid, useful calculations that should be freely shared. Here they are, smoothed to the WO97 variable resolution, in ascii format.
Cool Dwarf
MS Turnoff Star

M31’s Heavy Element Distribution and Outer Disk, by G. Worthey, A. Espana, Lauren A. MacArthur, and Stephane Courteau. Astrophysical Journal, submitted. Manuscript: , m31.pdf

Balmer and Metal Feature Absorption Gradients in M32, by G. Worthey, 2004, Astronomical Journal, 128, 2826.
+ Preprint (one column, big figures, 23 pages): [ps], or

+ Preprint (two columns, small figures, 16 pages): [ps], or

Extra plots: H beta versus metals.eps, H delta A versus metals.eps, H gamma A versus metals.eps, H delta F versus metals.eps, H gamma F versus metals.eps, Table of all index measurements (text), Table of smoothed index measurements (text version of Table 1), Table of smoothed index measurements (text version of Table 2).

The Mg-sigma Relation and the Genesis of Early-Type Galaxies, by G. Worthey & M. Collobert. 2003 Astrophysical Journal vol. 586, p. 17. Resource Page: (manuscript, big figures, extra figures).

The Metal Abundances of NGC 188 and NGC 6791 from Low Resolution Spectra, by G. Worthey & Kelly J. Jowett, 2003 PASP, vol. 115, p. 96. Download the manuscript ( or paper.pdf) and the data in Table 1 ( or data.pdf).

Guy Worthey

Associate Professor of Physics

Office: Webster Physical Sciences 948C
Phone: (509) 335-4994
Fax: (509) 335-7816
E-mail: gworthey at

Research: Astrophysics, Observation Cosmology, Stellar Populations

WebsiteJewett Observatory, WSU Planetarium