Adolescent galaxies: Trajectories and transitions in adulthood
Some human teenagers are described as eccentric, and this is also the case in astrophysics, as some galaxies can be described as “adolescent” in some of their early stages of growth, due to the chaos and mutations they can undergo, in addition to containing a heavy metal that scientists did not expect to exist in the future. The former, which is nickel.
In a study published November 20 in The Astrophysical Journal Letters, a team of astrophysicists analyzed the first results of the Survey of Tethered Chemical Evolution in Interstellar Auroras, a program using NASA’s James Webb Space Telescope. To study the chemistry of distant galaxies.
According to the early results of this study, the so-called “teenage galaxies”, that is, those that formed between two and three billion years after the Big Bang, were unusually hot, and contained elements that are difficult to observe and that scientists did not expect to exist, such as nickel.
The researchers focused on 33 distant galaxies for 30 straight hours, then combined the wavelengths of light collected from 23 of those galaxies to create a composite picture of what’s happening in these structures. These wave spectra contain clues regarding things like average temperatures and the elements that may be lurking within them.
“We are trying to understand how galaxies have grown and changed over 14 billion years of cosmic history, using the James Webb Space Telescope,” says Allison Strom, lead author of the study and assistant professor of physics and astronomy at Northwestern University in Illinois in the US. “Adolescence is a chaotic time of growth spurts and change. Teenagers often have experiences that shape their paths into adulthood. It’s the same with galaxies.”
The composite picture of galaxies contains eight identifiable elements: hydrogen, helium, nitrogen, oxygen, silicon, sulfur, argon, and nickel. While lighter elements were expected, the presence of nickel, which is heavier than iron in the periodic table, came as somewhat of a surprise.
“I never imagined, even in my wildest dreams, that we could find nickel.” Strom says, in a statement to Al-Arabi Al-Jadeed, that even in ancient galaxies close to our galaxy, the presence of nickel is rarely observed, after multiple life cycles of stars, which means multiple rounds of supernovae, providing the opportunity for heavier elements to collect and spread throughout. across the galaxy.
The researcher likens the galaxy’s spectra to its “chemical DNA.” By examining this DNA during the galaxy’s “teenage” years, scientists can better understand how it has grown and how it will evolve into a more mature galaxy. Astrophysicists still don’t understand why some galaxies appear red and barren, meaning no new stars are forming, while others, like our Milky Way, are still forming stars.
A galaxy’s spectrum can reveal its key elements, such as oxygen and sulfur, which provides a window into what the galaxy was doing previously and what it could do in the future.
The results of the study also showed that the teenage galaxies were extremely hot, with temperatures reaching more than 13,350 degrees Celsius, at a time when scientists were accustomed to monitoring temperatures approaching 9,700 degrees Celsius in the hottest pockets of the galaxies. “This is just further evidence of how the nature of galaxies may have been different when they were younger,” Strom said. “Ultimately, the fact that we see a higher characteristic temperature is just another manifestation of different chemical DNA, because the temperature and chemistry of gas in galaxies are intrinsically linked.” .
