In a recent study utilizing the James Webb Space Telescope, astronomers identified an ancient galaxy exhibiting an unconventional light signature. This discovery was made while examining the early universe.
Following an in-depth analysis of the data, scientists concluded that the exceptional brightness of this galaxy is not due to its stars but rather to space gas. The research, published in the “Monthly Notices of the Royal Astronomical Society,” suggests this phenomenon might fill a gap in the current understanding of cosmic history. It indicates a previously unrecognized phase in galaxy evolution where superheated gas clouds can outshine their stars.
Harley Katz, an astrophysicist from the universities of Oxford and Chicago, commented on the findings in a statement, noting that, “It looks like these stars must be much hotter and more massive than what we see in the local universe,” a conclusion drawn from the vastly different conditions of the early universe.
The James Webb Space Telescope, a collaborative project between NASA and its European and Canadian counterparts, was specifically designed to study an early period of the cosmos by detecting invisible light at infrared wavelengths. This capability enables it to see through the dust and gas that obscure distant and dim light sources.
Webb has successfully observed some of the oldest and faintest light in existence, including that from the galaxy GS-NDG-9422, which existed approximately 1 billion years after the Big Bang. For context, the current estimated age of the universe is around 13.8 billion years.
Scientists propose that this galaxy is undergoing significant star formation within a dense gas cocoon, producing massive, hot stars. The intense light from these stars may be causing the surrounding gas to emit an unusually bright glow.
Researchers also used computer models to simulate the impact of hot, massive stars on gas clouds. These models demonstrated that the gas could indeed be more luminous than the stars, closely matching the Webb telescope’s observations of GS-NDG-9422.
Typically, hot, massive stars in the Milky Way have temperatures ranging from 70,000 to 90,000 degrees Fahrenheit. However, the stars in this distant galaxy appear to reach temperatures as high as 144,000 degrees Fahrenheit.
Cosmologists have theorized that gas could outshine stars within the first generation of stars in the universe, known as Population III stars. Identifying these pristine, pure-bred stars remains a significant goal in modern astrophysics.
Most of the universe’s chemicals are believed to originate from exploded stars. Therefore, it is logical to assume that the firstborn stars comprised almost entirely hydrogen and helium, the primary materials from the Big Bang. As stars died and enriched the universe with heavier elements, newer generations of stars formed with more diverse compositions.
Despite the fact that GS-NDG-9422 does not appear to host the elusive Population III stars — its light is too chemically complex — it seems to represent an intermediate stage between the universe’s initial stars and those typically found in more mature galaxies. Researchers are now investigating whether this phenomenon is common among galaxies of this era.
Alex Cameron, the lead author from Oxford, reflected on the discovery, stating, “My first thought in looking at the galaxy’s spectrum was, ‘that’s weird,’ which is exactly what the Webb telescope was designed to reveal.” The telescope is uncovering “totally new phenomena in the early universe that will help us understand how the cosmic story began.”
