A method to determine distances to molecular clouds using near-IR photometry

Abstract

<i>Aims. <i/>We aim to develop a method to determine distances to molecular clouds using <i>JHK<i/> near-infrared photometry.<i>Methods. <i/>The method is based on a technique that aids spectral classification of stars lying towards the fields containing the clouds into main sequence and giants. In this technique, the observed () and () colours are dereddened simultaneously using trial values of <i>A<i/><sub><i>V<i/><sub/> and a normal interstellar extinction law. The best fit of the dereddened colours to the intrinsic colours giving a minimum value of then yields the corresponding spectral type and <i>A<i/><sub><i>V<i/><sub/> for the star. The main sequence stars, thus classified, are then utilized in an <i>A<i/><sub><i>V<i/><sub/> versus distance plot to bracket the cloud distances.<i>Results. <i/>We applied the method to four clouds, L1517, Chamaeleon I, Lupus 3 and NGC 7023 and estimated their distances as , , and pc respectively, which are in good agreement with the previous distance estimations available in the literature.