2MASS Two-color Interstellar Reddening Line in the Direction of the North America and Pelican Nebulae and the Cyg OB2 Association

TL;DR

This study determines the interstellar reddening line slope in the near-infrared color-color diagram for specific celestial regions, revealing a higher ratio than typically assumed, which impacts understanding of dust extinction.

Contribution

The paper provides a new measurement of the reddening line slope in the J-H vs. H-Ks diagram for the North America and Pelican nebulae, Cyg OB2, and related dust clouds, using 2MASS data and spectral classifications.

Findings

E(J-H)/E(H-Ks) ratio is 2.0, higher than the typical 1.7-1.8.

The ratio varies across different spectral groups.

Results improve understanding of interstellar dust properties.

Abstract

The slope of the interstellar reddening line in the J-H vs. H-Ks diagram of the 2MASS survey in the direction of the North America and Pelican nebulae, the L935 dust cloud and the Cyg OB2 association is determined. The MK types were either classified by C. J. Corbally or collected from the literature. The ratio E(J-H)/E(H-Ks) = 2.0 is obtained by taking the average for the four groups of spectral classes: O3--B1, B2--B6, B7--B9.5 and red clump giants. The obtained ratio is larger than the `typical' value, 1.7-1.8.