Webb space telescope spies precocious ‘teenage’ galaxies

Light from 23 distant galaxies, identified with red rectangles in the Hubble Space Telescope image at the top, was combined to capture incredibly faint emission from eight different elements - hydrogen, helium, nitrogen, oxygen, silicon, sulfur, argon and nickel - which are labelled in the James Webb Space Telescope spectrum
Light from 23 distant galaxies

Since it started operating last year, the James Webb Space Telescope has made ground-breaking discoveries about some of the earliest galaxies in the cosmos. They could be referred to as galactic babies.

However, Webb has gotten even better information on galaxies that are a little bit more developed. These are known as the galactic “teenagers” by astronomers. Furthermore, according to recent studies, they exhibit characteristics of human adolescence, such as development spurts and a hint of immaturity.

The researchers concentrated on galaxies that originated between two and three billion years after the universe was created approximately 13.8 billion years ago, during the Big Bang event. Using Webb’s averaged data on light at different wavelengths coming from 23 galaxies—their “chemical DNA”—the study created a composite image of teenage galactic traits.

Lead author Allison Strom, a physics and astronomy professor at Northwestern University in Illinois, said of the teenage galaxies, “They have very unique chemical DNA, which indicates that they have formed a decent number of stars – they’re fairly grown already – but still growing rapidly.” The study was published this week in the Astrophysical Journal Letters.

The researchers found that these galaxies do not yet appear or behave like galaxies do today.

“They go through some important processes around this time – many of which we don’t yet understand and hope to soon understand better – which sets what type of galaxy they will become,” said Gwen Rudie, a co-leader of the study and an astronomer at Carnegie Observatories in California.

Around 24,000 degrees Fahrenheit (13,350 degrees Celsius) was the temperature of the gas found in star-forming regions, or stellar nurseries, of young galaxies, which was significantly hotter than the gas found in galaxies today.

“The temperature in these parts of galaxies is dominated by the young stars and the properties of the gas, so finding a different temperature means that there is something different about the stars and gas in the teenage galaxies,” Strom stated.

Eight elements—hydrogen, helium, oxygen, nitrogen, sulfur, argon, nickel, and silicon—were seen to be shining in the galaxies.

Oxygen is remarkable because it’s one of the most crucial elements of “galaxy DNA” for monitoring previous growth. In addition, oxygen is the third most common element in the universe, behind helium and hydrogen, according to Strom.

“The nickel was unexpected because, although we anticipated that there might be some nickel present, even in really close galaxies, it typically does not glow brightly enough to be seen. Thus, its discovery was unexpected and could suggest that the huge stars that light in the gas have a unique quality,” Strom continued.

According to Rudie, these galaxies most likely contain additional elements than just these eight that have not yet been discovered.

“Because elements heavier than hydrogen and helium are predominantly formed in stars, knowing what galaxies are made of tells us about how many stars they formed in the past and how quickly that happened,” Strom stated.

The results, according to Strom, “point toward a picture where these galaxies are still chemically ‘immature’ and are forming very quickly.”

Launched in 2021, Webb started data collection last year and has changed our knowledge of the early universe.

The recently published research offers the first findings from the CECILIA Survey, which employs Webb to examine the chemistry of far-off galaxies. CECILIA stands for Chemical Evolution Constrained utilizing Ionized Lines in Interstellar Aurorae, and it honors Cecilia Payne-Gaposchkin, a trailblazing astronomer of the 20th century.

“There has rightfully been a lot of excitement about how Webb has enabled us to view some of the very first galaxies, but even with Webb, our ability to say much about those galaxies is limited,” Strom stated. “At the same time, the telescope is letting us observe galaxies a little later in the universe’s history in a stupendous amount of detail, and CECILIA is the first and, so far, the best example of this.”


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