REVISION OF STELLAR INTRINSIC COLORS IN THE INFRARED BY SPECTROSCOPIC SURVEYS

Abstract

Intrinsic colors of normal stars are derived in the popularly used infrared bands involving the Two Micron All-Sky Survey/ JHK S , Wide-field Infrared Survey Explorer , Spitzer /IRAC, and AKARI /S9W filters. Based on three spectroscopic surveys—LAMOST, RAVE, and APOGEE, stars are classified into groups of giants and dwarfs, as well as metal-normal and metal-poor stars. An empirical analytical relation of the intrinsic color is obtained with stellar effective temperature for each group of stars after the zero-reddening stars are selected from the blue edge in the versus diagram. It is found that metallicity has little effect on the infrared colors. In the near-infrared bands, our results agree with previous work. In addition, the color indexes and , which are taken as constant to calculate interstellar extinction, are discussed. The intrinsic colors of M-type stars are derived separately due to the lack of accurate measurement of their effective temperature.