The James Webb Space Telescope (JWST), a cutting-edge instrument in space exploration, has recently shed light on the mysteries of young stellar objects (YSOs) within the NGC 346 open cluster. Published on April 24 and available on the arXiv preprint server, the study conducted by an international team of astronomers presents invaluable insights into the properties and characteristics of YSO populations within this dynamic cluster.
Young stellar objects represent stars in their early evolutionary stages, including protostars and pre-main sequence (PMS) stars. Typically found in dense molecular clusters teeming with molecular gas and interstellar particles, these YSOs are pivotal in understanding star formation processes.
NGC 346, situated approximately 202,000 light years from Earth, stands as a beacon of stellar activity within the Small Magellanic Cloud (SMC). As a young open cluster, NGC 346 offers a rich tapestry of stellar populations, ranging from massive, evolved stars to the intriguing low-mass YSOs.
Led by Nolan Habel from NASA's Jet Propulsion Laboratory (JPL), the team utilized JWST's advanced Near Infrared Camera (NIRCam) and MidInfrared Instrument (MIRI) to delve into the intricate stellar makeup of NGC 346, with a keen focus on its YSO constituents.
The study commenced with the detection of an impressive 203,891 unique sources within NGC 346 using JWST's NIRCam and MIRI. Subsequently, the researchers meticulously pinpointed 196 YSOs and PMS stars from this dataset, ensuring a high level of confidence suitable for in-depth spectroscopic investigations.
Noteworthy findings include the identification of 833 objects within NGC 346 exhibiting substantial mid-infrared excess. These objects, closely associated with regions rich in diffuse dust and gas, strongly indicate their YSO nature, adding layers to our understanding of star formation dynamics.
Employing spectral energy distribution (SED) fitting techniques, the team scrutinized 77 sources, ultimately classifying 23 of them as young stellar objects with definitive characteristics. These 23 YSOs display a diverse range of sizes, spanning from 0.14 to 82.32 solar radii, alongside masses ranging from 0.95 to 4.15 solar masses. Bolometric temperatures of these objects vary widely, from 2,051 to 17,930 K, showcasing the dynamic nature of YSOs within NGC 346.
Of particular interest is CN202153, the least massive extragalactic YSO identified thus far, emphasizing the unique nature of NGC 346 within the cosmic landscape. The researchers advocate for future near-infrared spectroscopic studies with JWST to unravel the intricacies and properties of the identified 23 YSOs, paving the way for deeper insights into star formation processes within NGC 346 and beyond.