Abstract:
Extinction correction is essential for studying the intrinsic properties of celestial objects within and beyond the Milky Way. With Gaia achieving photometric precision at the level of one thousand, higher accuracy in extinction correction is now demanded. Thanks to precise atmospheric parameters of LAMOST and with the “star-pair” technique, we have obtained high-precision (errors ~0.01-0.03 mag) multi-band reddening measurements from the FUV to the mid-IR and extinction curves for millions of stars, leading to significant advancements in precise reddening correction of the Milky Way dust.
Firstly, we quantified the “bandwidth effects” of extinction and established an empirical relationship between reddening coefficients, temperature, and extinction, effectively resolving inconsistencies reported in previous studies. Secondly, we mapped the 2D distribution of the dust property parameter Rv across the Milky Way. For the first time, we observed that Rv values inside molecular clouds are lower than in surrounding regions, attributing this to the partial protection of small dust grains within translucent clouds from destructive processes.
Recently, by combining Gaia XP spectra, we directly measured the mean extinction curve of the Milky Way using approximately 370,000 high-quality spectra. This effort not only confirmed several known intermediate-scale structures in the extinction curve but also identified a new one. These structures exhibit correlations with the extinction magnitude, Rv, and diffuse interstellar bands (DIBs).
