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For over thirty years, the Hubble Space Telescope has been making groundbreaking discoveries that help us better comprehend the universe. Recently, a team of scientists and engineers conducted one of the largest and most ambitious Hubble programs ever executed. They gathered data on nearly 500 stars over a span of three years, resulting in new insights into the formation, evolution, and impact of stars on their surroundings.
In December 2023, astronomers completed the ULLYSES (Ultraviolet Legacy Library of Young Stars as Essential Standards) survey. It provides a comprehensive spectroscopic dataset in ultraviolet light. Since UV light can only be observed from space, Hubble is the only active telescope capable of conducting this research. The obtained dataset is expected to be valuable for decades to come.
The ULLYSES team conducted a study on 220 stars and combined their observations with data from the Hubble archive on 275 additional stars. The program also included information from some of the world’s largest and most powerful ground-based telescopes and X-ray space telescopes. The ULLYSES dataset contains stellar spectra that provide information about each star’s temperature, chemical composition, and rotation.
What are we seeing?
ULLYSES is a program that analyzes two types of stars: super-hot, massive, blue stars and young stars that are less massive than our Sun. The blue stars are incredibly bright and emit ultraviolet light that Hubble can detect. Their strong winds shape galaxy evolution and supply galaxies with elements necessary for life. These elements are created through nuclear fusion and then released into space as the star dies. ULLYSES is focused on blue stars found in nearby galaxies that lack elements heavier than helium and hydrogen, which were prevalent in the early universe.
The young stars that are less massive than the Sun emit high-energy radiation, including ultraviolet light and X-rays, while they are still growing. They gain mass by collecting material from the disks of dust and gas surrounding them that form planets. The Hubble spectra provide essential information about the process by which young stars gain mass and the amount of energy released into the surrounding planet-forming disk and nearby environment. The ultraviolet light emitted by young stars affects the formation of planets and their habitability. The target stars in this category are located in nearby star-forming regions within our Milky Way galaxy.
Credits: NASA, ESA, STScI
Julia Roman-Duval, Implementation Team Lead for ULLYSES at the Space Telescope Science Institute (STScI) in Baltimore, Maryland, commented.
“I believe the ULLYSES project will be transformative, impacting overall astrophysics – from exoplanets, to the effects of massive stars on galaxy evolution, to understanding the earliest stages of the evolving universe. Aside from the specific goals of the program, the stellar data can also be used in fields of astrophysics in ways we can’t yet imagine.”
[via Space.com]
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