Stellar contents and star formation in IRAS 18456-0223

Abstract

We use various analytical techniques to study Young Stellar Objects (YSOs) in an area of approximately 10'×10' in the IRAS 18456-0223 star-forming region. We use archival optical (Gaia DR3) and infrared (2MASS, UKIDSS, Spitzer, WISE, and Herschel) data and our optical spectroscopy of three bright stars for this purpose. We identify 89 YSOs (80 class II and 9 class I), based on their infrared properties. Our multiwavelength SED fits of select YSOs show that they have masses ∼0.1─7.2 M⊙ and are upto 4 Myr old. Our Minimum Spanning Tree (MST) analysis shows that these YSOs, situated at around 600 pc, form clusters with radial extent of order 0.5pc and mean surface densities ∼60pc-2. We compare UKIDSS and 2MASS data of the YSOs and find that some of them show variability. We constructed maps based on Herschel data which reveal multiple column density peaks (NH2∼1022cm-2) embedded in cold (Td∼10-13 K) filaments. Our near-infrared extinction map exhibits several high-AV peaks, some of which coincide with the sub-mm column density maxima. Using our optical spectra of three bright sources, we show that they are of A-K type. One star shows the Li I 6707 Å line, indicating its youth.