The Impact of Stellar Model Spectra in Disk Detection

Abstract: We present a study of the impact of different model groups in the detection of circumstellar debris disks. Almost all previous studies in this field have used Kurucz model spectra to predict the stellar contribution to the flux at the wavelength of observation thus determining the existence of a disk excess. Only recently have other model groups or families like Marcs and NextGen-Phoenix become available to the same extent. This study aims to determine whether the predicted stellar flux of a disk target can change with the choice of model family - can a disk excess be present in the use of one model family whilst being absent from another? A simple comparison of Kurucz model spectra with Mrcs and NextGen model spectra of identical stellar parameters was conducted and differences were present at near-infrared wavelengths. Model spectra often do not extend in wavelength to that of observation and therefore extrapolation of the spectrum is required. In extrapolation of model spectra to the Spitzer MIPS passbands, prediction of the stellar contribution differed by 5 % at 70mum for F, G and early K spectral types with differences increasing to 15% for early M dwarfs. Analysis of the Spitzer MIPS 24mum observations of 37 F, G and K solar-like stars in the Pleiades cluster was conducted. In using Kurucz model spectra, 7 disk excesses were detected while only 3 and 4 excesses were detected in using Marcs and NextGen-Phoenix model spectra respectively.