Theoretical Isochrones with Extinction in the K Band . II . J – K versus K
نویسندگان
چکیده
We calculate theoretical isochrones in a consistent way for five filter pairs near the J and K band atmospheric windows (J–K, J–K , J–Ks, F110W–F205W, and F110W– F222M) using the Padova stellar evolutionary models of Girardi et al. We present magnitude transformations between various K-band filters as a function of color. Isochrones with extinction of up to 6 mag in the K band are also presented. As found for the filter pairs composed of H & K band filters, we find that the reddened isochrones of different filter pairs behave as if they follow different extinction laws, and that the extinction curves of Hubble Space Telescope NICMOS filter pairs in the color-magnitude diagram are considerably nonlinear. Because of these problems, extinction values estimated with NICMOS filters can be in error by up to 1.3 mag. Our calculation suggests that the extinction law implied by the observations of Rieke et al for wavelengths between the J and K bands is better described by a power-law function with an exponent of 1.66 instead of 1.59, which is commonly used with an assumption that the transmission functions of J and K filters are Dirac delta functions. Subject headings: Hertzsprung-Russell diagram — techniques: photometric — stars: fundamental parameters — infrared: stars
منابع مشابه
Theoretical Isochrones with Extinction in the K-Band
We calculate theoretical isochrones, in a consistent way, for five filters in the atmospheric window between 1.9μm and 2.5μm, 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 p...
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