From jmc@phobos.caltech.edu Sat Jun 11 19:54:34 2005 Subject: FEPS cluster paper X-IMAPbase: 1121927350 1 Status: O X-Status: X-Keywords: X-UID: 1 As many of you know, Lynne and I are leading a paper to analyze the IRAC/MIPS/IRS-low data for the FEPS cluster sample. We have produced a rough outline, which you will find below. If you would like to participate in this paper, please send me an email and we will be sure to include you in any future discussions. Any comments/suggestions on the outline are of course welcome! John ******************************************************************************* Goal: Establish temporal evolution of dust disks around solar-type stars from 5 to 600 Myr based on the FEPS cluster sample. Deadline to submit paper: optimistic : end of August realistic goal : before PP V, in time to present a poster on the results I. Introduction --- Summarize historical efforts to establish temporal evolution of dust --- Will likely cover debris disks. Will wait and see how much to include primordial disks. IRAS : Backman PPIII ISO : Habing etal., Spangler etal., Decin etal, a few others Spitzer: Rieke etal., and a few cluster papers Submm : Carpenter etal, Liu, Wyatt --- Goal of FEPS --- Focus on solar-type stars to place our solar-system in context --- Clusters in this paper --- Clusters + field in subsequent work II. Sample a) Table 1: List of Clusters Cluster Ntot With IRAC With MIPS With IRS With All --------- ------ -------- --------- -------- -------- RCrA 7 7 7 7 7 Upper Sco 14 13 13 14 13 LCC 14 14 12 14 12 UCL 23 23 20 23 20 IC2602 5 0 0 5 0 Alpha Per 13 6 6 13 6 Pleiades 20 19 19 20 19 Hyades 22 6 14 22 5 QUESTION: How should we select the sample? The IRS will be the focus of the analysis, so we could just require that dataset. b) Adopted cluster ages, distances, uncertainties III. Observations and Data Reduction a) IRAC/IDP3 b) MIPS (24um - APEX???; 70um - IDP3 or APEX???) c) IRS low May not need MIPS 24um given the high quality of IRS low spectra. Definitely need MIPS 70um though. IV. SNR and Uncertainties Goal: Establish a high level of confidence in the data Distinguish between three points a) Signal to noise ratio (i.e. how well a source is detected) b) Internal uncertainty (i.e. how precise we can measure the photometry) c) Calibration uncertainty (i.e. how accurately we can measure the photometry) d) Kurucz model uncertainties Demonstate we can quantify each of these measures. a) Signal to noise ratio --- Define signal to noise ratio. Show histograms of the SNR for each band/wavelength??? b) Internal uncertainty --- Define internal uncertainty --- For IRAC, quantify internal uncertainty based on dispersion in irac colors. --- For MIPS, quantify internal uncertainty based on dispersion in irac-MIPS colors. c) Calibration uncertainty/Kurucz models --- Define relative to Kurucz model fits --- Not clear we can separate the two based on our data alone. V. Analysis a) Measure infrared excess relative to Kurucz models and/or colors We want more than just the Rieke plot. 1) Photometric bands 2) Spectra --> Plot excess vs. wavelength b) Disk properties 1) Derive teff from fit to IRS spectrm + photometry 2) Derive L_fir from spectrum 3) Establish lambda_onset which IR excess appears (-> Rinner) 4) Lir/L* vs. Tdust 5) Excesses/properties vs. age VI. Interpretation 1) Establish evolution relative to T Tauri stars Is Upper Sco sample different relative to T Tauri stars. has been establish already for IRAC data in Murray's paper, but not for 24um and 70um data. Not clear if T Tauri data exists yet for this comparison. 2) Diversity in disk properties (temp/radii, magnitude of excess) (Is sample big enough) 3) Comparison of evolution results to A-stars 4) Inside out vs. simultaneous disappearance and then reapparance at large radii 5) How common is our solar system? I am refluctant to include toy model in this paper until it is published. Use Dana's toy model for the solar system to overlay on above diagnostic plots. This will immediately indicate how the mean/median disk properties compare with our Solar System. This can be analyzed both as a function of age, or as an ensemble. Appendix: Kurucz model fitting details Potential issues to address: 1) Kurucz vs. empirical 2) binaries 3) variability *******************************************************************************