The chaotic childhoods of stars

Newborn stars live turbulent, unpredictable early lives before settling into the calm of adulthood (Aryabhatta Research Institute of Observational Sciences (ARIES). Stars are often thought of as steady, shining beacons in the night sky. But according to new research their earliest years are anything but calm.

The study examined over 22,000 Young Stellar Objects (YSOs), stars in their infancy, across massive star-forming regions of the Milky Way. These stellar nurseries, dense clouds of gas and dust, are chaotic environments where newborn stars draw in material under gravity, forming discs of gas that eventually ignite hydrogen fusion, marking the star’s birth.

The process over time

Using more than a decade of mid-infrared data from NASA’s WISE and NEOWISE missions, the researchers tracked how the brightness of these young stars fluctuates over time. What they found was a cosmic rollercoaster: some YSOs flicker unpredictably, others steadily dim or brighten, while a few fluctuate in regular cycles. These changes reveal the dynamic processes shaping the stars’ early development, from bursts of accretion, where the star pulls in material from its disc to the clearing of material in the inner disc.

About 26 percent of the stars studied exhibited detectable variability, most commonly in irregular patterns. Interestingly, while most variable stars became redder as they brightened, a notable number also became bluer, signaling complex interactions with their surrounding discs.

To aid future research, the team compiled a catalogue of over 5,800 variable YSOs, creating a publicly available resource for astronomers studying stellar formation, disc evolution, and accretion processes. Their findings offer an unprecedented window into the tumultuous “childhoods” of stars, a reminder that even the most luminous objects in the sky begin their lives in chaos.