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Yale Astronomy

Spectroscopic Analysis


Planet Metalicities

We use Spectroscopy Made Easy (SME) (Valenti & Piskunov 1996) to generate synthetic spectra that match observations. There are many possible free parameters in the synthetic model, including effective temperature, elemental abundances, stellar rotation (vsini), and surface gravity. Using atomic line data that were tuned to the solar spectrum, we analyzed spectra for more than 1,000 stars on the California Planet Search program (Valenti & Fischer 2005) to derive a correlation between the presence of close-in gas giant planets and metallicity of the host star, shown in the figure above (Fischer & Valenti 2005).

The SME code and our atomic line lists are available on Jeff Valenti's web site at STScI.

SME Tutorial by K.L. Tah
New to spectral synthesis modeling using SME? This tutorial is great place to start exploring the power of this incredible software tool. Download the pdf and start SME from the IDL command line, and you’re ready to go.

Our catalog from "Stellar Properties of Cool Stars. SPOCS I" is searchable or available for download.

Using SPOCS I and parameter covariances, Takeda et al. (2008) used Bayesian analysis to calculate theoretical evolutionary tracks and derive supplementary stellar parameters: stellar masses, radii and ages. The data table from this paper, "Structure and Evolution of Nearby Stars with Planets II. Physical Properties of ~1,000 Cool Stars from the SPOCS Catalog," is available for download.

Related Papers

  1. Greaves, J.S., Fischer, D.A., Wyatt, M.C. 2006, Metallicity, debris discs and planets, MNRAS, 366, 283.
  2. Robinson, S.E., Laughlin, G., Bodenheimer, P., Fischer, D., 2006 Silicon and Nickel Enrichment in Planet Host Stars: Observations and Implications for the Core Accretion Theory of Planet Formation, ApJ 643, 484.
  3. Takeda, G., Ford, E., Sills, A., Rasio, F., Fischer, D., Valenti, J. 2006, Structures and Evolution of Nearby Stars with Planets II. Physical Properties of ~ 1,000 Cool Stars from the SPOCS Catalog, ApJS, 168, 297
  4. Fischer & Valenti 2005, Planet Metallicity Correlation, ApJ 622, 1102.
  5. Valenti, J. A., Fischer, D. A. 2005, Spectroscopic properties of cool stars (SPOCS). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs, ApJS 159, 141
  6. Valenti, J. A., Piskunov, N. 1996, Spectroscopy made easy: A new tool for fitting observations with synthetic spectra, A&AS, 118, 595