| Theoretical isochrones with extinction in the K band (2005) | |||||||||||||||
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| To appear PASP p Theoretical Isochrones with Extinction the Band Sungsoo Kim Donald Figer Myung Gyoon Lee and Seungkyung arXiv astro May ABSTRACT calculate theoretical isochrones consistent way for five filters the atmospheric window between and W and using the Padova stellar evolutionary models Girardi Even when displayed the same Vega magnitude system the near infrared colors the same isochrone can differ mag its bright end depending the filter present magnitude transformations between band filters function color from band filters Isochrones with extinction up mag are also presented find that care needed when comparing extinction values that are estimated using different filter sets the band particular when comparing those between atmospheric and space filter sets extinction values for space filters can error mag reduce this error introduce effective extinction slope for each filter set and isochrone model which describes the extinction behaviour isochrones the color magnitude diagram more correctly than the actual extinction law Our calculation also suggests that the extinction law implied the observations Rieke Rieke Paul for wavelengths between and bands better described power law function with exponent instead which commonly used with assumption that the transmission functions and filters are Dirac delta functions Subject headings Hertzsprung Russell diagram techniques photometric stars fundamental parameters infrared stars INTRODUCTION Deep near infrared stellar photom. We calculate theoretical isochrones, in a consistent way, for five filters in the atmospheric window between 1.9 µm and 2.5 µm, K, K′, Ks, F205W, and F222M, using the Padova stellar evolutionary models by Girardi et al. Even when displayed in the same Vega magnitude system, the near-infrared colors of the same isochrone can differ by up to 0.18 mag at its bright end, depending on the filter. We present magnitude transformations between K-band filters as a function of color from H & K band filters. Isochrones with extinction at K of up to 6 mag are also presented. We find that care is needed when comparing extinction values that are estimated using different filter sets in the K-band, in particular when comparing those between atmospheric and space filter sets: extinction values for space filters can be in error by up to 0.3 mag. To reduce this error, we introduce an “effective extinction slope” for each filter set and isochrone model, which describes the extinction behaviour of isochrones in the color-magnitude diagram more correctly than the actual extinction law. Our calculation also suggests that the extinction law implied by the observations of Rieke, Rieke, & Paul for wavelengths between H and K bands is better described by a power-law function with an exponent of 1.61, instead of 1.55, which is commonly used with an assumption that the transmission functions of H and K filters are Dirac delta functions. (Refer to PDF file for exact formulas).. This work was supported by the research fund from Kyung Hee University. S.S.K. was supported by the Astrophysical Research Center for the Structure and Evolution of the Cosmos (ARCSEC) of Korea Science and Engineering Foundation through the Science Research Center (SRC) program. M.G.L. was in part supported by the ABRL (R14-2002-058-01000-0) and the BK21 program. | |||||||||||||||
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