(ORDO NEWS) — A group of Danish and American astronomers conducted a “stellar census” of more than 140 thousand galaxies and found that the most distant of them, as a rule, have more massive stars than the Milky Way.
Although astronomers do not even have a complete census of all the hundreds of billions of stars contained in the Milky Way galaxy, they can select enough of them to get a good idea of the average stellar population.
Scientists generally know how many small dwarf stars there are, how many medium-sized ones like the Sun, and how many stellar giants. It is extremely difficult to repeat the same for other galaxies.
Most of them are too far from the Earth to identify and study individual stars in them. Usually it is possible to observe only the brightest and most massive luminaries, and one has only to guess about the populations of smaller stars.
As a general rule, astronomers start from the assumption that the “demography” of any distant galaxy generally corresponds to that observed in the Milky Way,
However, now a team of researchers who have used the COSMOS catalog to study 140,000 individual galaxies and developed special methods for estimating the stellar population in each of them by parametrizing the universal initial stellar mass function by selecting the most appropriate photometric templates have managed to find out that distant galaxies, as a rule, contain on average larger stars than the Milky Way.
At the same time, our galactic neighbors did not have such sharp differences. “We were only able to see the tip of the iceberg, although we had long suspected that it was not a good idea to assume that other galaxies would be similar in every way to ours, it was not a good idea,” explains one of the co-authors of the study, Charles Steinhardt from the Niels Bohr Institute at the University of Copenhagen.
However, no one has ever been able to show that other galaxies form different populations of stars. Our study opens the door to a deeper understanding of the formation and evolution of galaxies.”
According to the researchers, the new discovery will have a very wide range of consequences – from reevaluating many data on distant galaxies to rethinking their evolution over the past billions of years.
In addition, it becomes clear why galaxies die over time – the most massive merged galaxies, according to the discovered trend, almost cease to form new stars.
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