Three-year Hubble study of young stars offers new insights into their formation, evolution

The NASA/ESA Hubble Space Telescope has successfully concluded one of its most ambitious programs to date, the Ultraviolet Legacy Library of Young Stars as Essential Standards (ULLYSES), amassing critical data on nearly 500 stars over three years. This effort marks a significant milestone in understanding stellar formation, evolution, and their profound influence on galaxies.

ULLYSES provides unparalleled spectroscopic data, meticulously capturing the ultraviolet (UV) light spectra of stars. Given that ultraviolet light cannot penetrate Earth's atmosphere, Hubble's unique position in space makes it the sole observatory capable of conducting this type of research. The program meticulously studied 220 stars directly, while incorporating data on an additional 275 stars from Hubble's extensive archives, alongside contributions from the world's most advanced ground-based and X-ray space telescopes.

The collected spectra offer invaluable insights into these celestial bodies' temperature, chemical composition, and rotational dynamics. ULLYSES' focused on both the luminous, massive blue stars, known for their intense UV brightness and critical role in galactic evolution, and the less massive, young stars that, despite their cooler and redder appearance, play a crucial role in the development of planetary systems.

Massive blue stars, shining a million times brighter than the Sun, were observed in detail for their powerful stellar winds. These winds are essential in driving the evolution of galaxies and enriching them with elements crucial for life. Studying such massive stars in element-deficient galaxies offers a glimpse into the early universe, shedding light on the formation of the first stars and their impact on young galaxies.

On the other hand, the investigation of younger, less massive stars sheds light on the processes of mass accumulation from their surrounding disks of dust and gas. This stage of stellar evolution is critical for understanding the formation of planets and the conditions that might allow for habitability.