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Researchers from the Aryabhatta Research Institute of Observational Sciences (ARIES) in Nainital analysed a decade’s worth of data from NASA’s WISE and NEOWISE missions to examine the early lives of young stellar objects (YSOs). By studying light curves of more than 22,000 stars, they classified variability patterns and revealed the turbulent processes that occur as stars are born.
Background
Young stellar objects are newly formed stars that have not yet begun stable hydrogen fusion in their cores. They form deep within dense molecular clouds when gravity causes gas and dust to collapse into a protostar surrounded by a rotating disc. Over time the protostar accretes material from the disc and eventually ignites nuclear fusion, entering the main sequence of the Hertzsprung–Russell diagram. This embryonic stage can last a few million years and is marked by dramatic brightness variations.
Key insights from the study
- Long‑term monitoring: Using infrared data from WISE/NEOWISE, scientists tracked light curves of over 22,000 YSOs in star‑forming regions like Orion and Perseus for ten years.
- Six variability categories: The team identified six distinct types of brightness changes — linear, curved, periodic, burst, drop and irregular. These patterns reflect phenomena such as unstable mass accretion, variable extinction and stellar rotation.
- Evidence of turbulent birth: Sudden bursts and dips in brightness show that material spiralling onto the star is often clumpy, leading to irregular accretion episodes. The study underscores that early stellar lives are far more dynamic than previously thought.
Why study YSOs?
- Understanding star formation: Observing YSOs helps astronomers unravel how stars gather mass, shed angular momentum and clear their surrounding envelopes.
- Clues to planet formation: The discs around young stars are the birthplaces of planets. Studying disc evolution and variability provides insight into how planetary systems like our own Solar System emerge.
Source: PIB