The Interstellar Reddening Law within 3kpc from the Sun

摘要

We have investigated the interstellar reddening law of young open clusters within 3kpc from the Sun using optical, near-IR 2MASS, and Spitzer IRAC data. The total-to-selective extinction ratio Ry of 162 young open clusters (log t_(age) ? 7.3) listed in the open cluster database WEBDA were determined from their color excess ratios. The young open clusters in the Sgr-Car arm show a relatively high value (R_v ≈ 3.2), those in the Per arm and in the Cygnus region have a smaller value (R_v ≈ 2.9), and those in the Moh-CMa regions have a nearly normal value (R_v ≈ 3.1).