Current disc galaxies often contain a thick outdoor disc and filled with stars and an integrated thin disk. For example, ours Milky Way Galaxy The thick disc is approximately 3,000 light years high and its slim disc about 1,000 light years thick.
How and why is this double disc structure formed? By analyzing the archive data of several observation programs by the James Webb space telescope of NASA, a team of astronomers is closer to the responses, as well as the understanding of the origins of disk galaxies in general.
The team carefully identified, visually checked and analyzed a statistical sample of 111 EDGE -On disc galaxies at various periods – up to 11 billion years ago (or approximately 2.8 billion years after the Big Bang). This is the first time that scientists have been studying thick and thin disk structures covering such distances, filling the gap between observers surveying the first universe and galactic archaeologists seeking to understand the history of our own galaxy.
“This unique measure of the thickness of the discs Shift Reds HighOr sometimes in the early universe, is a reference for the theoretical study which was only possible with Webb, “said Takafui Tsukui, the main author of the article and researcher at the Australian National University in Canberra.” Usually, the older thick disc stars are low, and the young stars of thin disc. But with the resolution of webb and unique capacity To see through the dust and highlight slight stars, we can identify the structure with two discs of the galaxies and measure their thickness separately. »»
By analyzing these 111 targets on cosmological time, the team was able to study the disc galaxies with discs and double disc galaxies. Their results indicate that the galaxies first form a thick disc, followed by a thin disc. The moment when it takes place depends on the mass of the galaxy: galaxies with a single high mass disc went to two -billion years ago. On the other hand, low -mass low -disc galaxies formed their thin discs integrated later, about 4 billion years ago.
“This is the first time that it is possible to resolve thin stellar discs with a higher red gap. What is really new discovers when thin stellar records are starting to emerge,” said Emily Wisnioski, co-author of the Australian National University Journal in Canberra. “See thin stellar discs already in place 8 billion years ago, or even earlier, was surprising.”
To explain this transition from a unique and thick disc to a thick and thin disc, and the difference in synchronization for high and low mass galaxies, the team looked beyond its galaxy sample with an initial edge and examined the data showing the moving gas from the Landes Atacamagame Miltimeter / Soummimer (Alma) and surveillance on the ground.
Taking into account the movement of galaxies gas discs, the team finds that their results align with the scenario of the “turbulent gas disc”, one of the three major hypotheses that have been proposed to explain the process of thick and thin disc form. In this scenario, a turbulent gas disc in the early universe causes training of intense stars, forming a thick stellar disc. As the stars are formed, they stabilize the gas disc, which becomes less turbulent and, therefore, more thin.
Since massive galaxies can more effectively convert gas to star, they settled sooner than their low -mass counterparts, resulting in the previous formation of thin discs. The team notes that the formation of thick and thin discs are not partitioned events: the thick disc continues to grow as the galaxy develops, although it is slower than the growth rate of the thin disc.
Webb sensitivity allows astronomers to observe smaller and lower galaxies, similar to ours, at first and with unprecedented clarity for the first time. In this study, the team noted that the transition period of the thick disc to a thick and thin disc coincides roughly with the formation of the slim disc of the milky galaxy galaxy. With webb, astronomers will be able to investigate the offspring more – galaxies that would have preceded the Milky Way – which could help explain the history of the formation of our galaxy.
In the future, the team intends to incorporate other data points into its sample of Galaxy Edge-on.
“Although this study structurally distinguishes thin and thick discs, there is still much more than we would like to explore,” said Tsukui. “We want to add the type of information that people generally obtain for neighboring galaxies, such as stellar movement, age and metallicity. In doing so, we can fill the ideas of the galaxies near and far, and refine our understanding of the training of the disc. ”
These results were published in the Monthly opinion from the Royal Astronomical Society.
The James Webb space telescope is the world’s leading world science observatory. Webb solves mysteries in our solar system, looking beyond the distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
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Laura Betz – laura.e.betz@nasa.gov
Nasa Goddard Space Flight CenterGreenbelt, md.
Abigail Major – amajor@scsci.edu
Institute of Sciences of the Space TelescopeBaltimore, md.
Hannah Braun – hbraun@scci.edu
Institute of Sciences of the Space TelescopeBaltimore, md.
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