Determination of absorption by Q-method for JHK photometry in embedded clusters

Abstract

In this paper we describe the absorption determination by the Q-method for 2MASS photometry ($J$, $H$ and $K_S$ bands). Using the Pleiades and Praesepe stars, we determine the zero-reddening sequence for different values of the color excess ratios $E(J-H)/E(H-K_S)$. In this paper we consider a sequence consisting of two segments, that leads to an uncertainty in the determining of absorption - one value of the Q parameter corresponds to two values of the non-reddened color index. We propose a method to select a segment of the zero-reddening sequence for the main sequence stars of the cluster. The method is based on the difference in the position of stars of different segments in the cluster luminosity function. To test the proposed method, we simulate the luminosity functions of clusters with the non-uniform absorption distribution in the cluster region. With the typical absorption values in embedded clusters, about 10 % of stars are erroneously assigned, but in some cases this fraction can reach 20 %. Thus, despite the fact that irregular absorption distorts the distribution of stars of different segments on the cluster luminosity function, our method allows to separate stars with an error of no more than 20 %.

14 pages, 4 figures, to be published in Astrophysical Bulletin

References in corpus (9)

• Gaia Data Release 3: Summary of the content and survey properties
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• The Optical to Mid-Infrared Extinction Law Based on the APOGEE, Gaia DR2, Pan-STARRS1, SDSS, APASS, 2MASS and WISE Surveys
• An Analysis of the Shapes of Interstellar Extinction Curves. VI. The Near-IR Extinction Law
• The complex, variable near infrared extinction towards the Nuclear Bulge
• A search for counterparts to massive X-ray binaries using photometric catalogues
• A large scale extinction map of the Galactic Anticenter from 2MASS
• A Newly Recognized Very Young Supernova Remnant in M83
• On the assessment of the nature of open star clusters and the determination of their basic parameters with limited data