2MASS Two-Color Interstellar Reddening Lines in the Inner Galaxy
  The slopes of interstellar reddening lines in the 2MASS J-H versus H-Ks
diagrams for 26 areas in the inner Galaxy (from Vulpecula to Centaurus) are
determined. For this aim we use the red-clump giants located inside and behind
spiral arms, or behind dense dust clouds of the Local arm. In most of the
investigated directions the ratio E(J-H)/E(H-K_s) is found to be between 1.9
and 2.0, taking the stars with the visual extinction less than 12 mag. The
stars with larger extinction deviate down from the reddening lines
corresponding to less reddened stars. Probably, this is related to the
curvature of reddening lines due to the band-width effect. However, some of the
deviating stars may be heavily reddened oxygen- and carbon-rich AGB stars
(giants of the latest M subclasses or N-type carbon stars), and
pre-main-sequence objects (YSOs).
