Abstract
In this paper, we describe the absorption determination with the \(Q\) -method for the 2MASS photometry ( \(J\) , \(H\) , and \(K_{S}\) bands).Using the Pleiades and Praesepe stars, we determine thezero-reddening sequence for different values of the color excessratios \(E(J-H)/E(H-K_{S})\) . In this paper, we consider a sequenceconsisting of two segments, that leads to an uncertainty in thedetermining of absorption—one value of the \(Q\) parametercorresponds to two values of the non-reddened color index. Wepropose a method to select a segment of the zero-reddeningsequence for the main sequence stars of the cluster. The method isbased on the difference in the position of stars of differentsegments in the cluster luminosity function. To test the proposedmethod, we simulate the luminosity functions of clusters with thenon-uniform absorption distribution in the cluster region. Withthe typical absorption values in embedded clusters, about 10 \(\%\) of stars are erroneously assigned, but in some cases this fractioncan reach 20 \(\%\) . Thus, despite the fact that irregular absorptiondistorts the distribution of stars of different segments on thecluster luminosity function, our method allows one to separatestars with an error of no more than 20 \(\%\) .
