The stars are heavier than we thought

10 in zone V (Laigle et al. 2016). At each redshift, the distribution is normalized separately to emphasize the temperature distribution at all redshifts. With increased redshift, fewer galaxies adapt to lower temperatures. Right: box-ground average value with standard deviation of optimum gas temperature at different background times (with average determined by objects in 2 Gyr wide buckets and no galaxies matching the temperature range limits). The average temperature is rising from ~ 28 to ~ 36 K from today to 12 Gyr, while the spread is decreasing. Unit: The European Physical Journal E (2022). DOI: 10.1140 / epje / s10189-022-00183-5″ width =”800″ height =”377″/>

Left: temperature of best adaptation from 10 to 50 K versus background time from a sample of 139,535 COSMOS2015 galaxies with S / N> 10 in zone V (Laigle et al. 2016). At each redshift, the distribution is normalized separately to emphasize the temperature distribution at all redshifts. With increased redshift, fewer galaxies adapt to lower temperatures. Right: box-ground average value with standard deviation of optimum gas temperature at different background times (with average determined by objects in 2 Gyr wide buckets and no galaxies matching the temperature range limits). The average temperature is rising from ~ 28 to ~ 36 K from today to 12 Gyr, while the spread is decreasing. Credit: The European Physical Journal E (2022). DOI: 10.1140 / epje / s10189-022-00183-5

A team of astrophysicists at the University of Copenhagen has reached a significant conclusion about star populations beyond the Galaxy. The result could change our understanding of a wide range of astronomical phenomena, including the formation of black holes, supernovae and why galaxies are dying.

For as long as humans have studied the heavens, what stars look like in distant galaxies has been a mystery. In a study published today in The Astrophysical JournalA team of researchers at the Niels Bohr Institute at the University of Copenhagen is challenging previous understandings of stars beyond our own galaxy.

Since 1955, the composition of stars in other galaxies in the universe has been assumed to be similar to that of the hundreds of billions of stars within ours – a mixture of large, medium, and low mass stars. But with the help of observations from 140,000 galaxies across the universe and a wide range of advanced models, the team has tested whether the same distribution of stars that is evident in our galaxy applies elsewhere. The answer is no. Stars in distant galaxies usually have larger masses than those in our “local neighborhood”. The finding has a significant impact on what we think we know about the universe.

“The mass of stars says a lot to us astronomers. If you change mass, you also change the number of supernovae and black holes resulting from huge stars. “So our result means we have to rethink a lot of things we once assumed, because distant galaxies look quite different from our own,” said Albert Sneppen, a graduate student at the Niels Bohr Institute and the study’s lead author.

Light from 140,000 galaxies was analyzed

The researchers assumed that the size and weight of the stars in other galaxies were similar to ours for more than fifty years, for the simple reason that they could not observe them through a telescope as they could with the stars in our own galaxy.

Distant galaxies are billions of light years away. As a result, only light from their most powerful stars reaches Earth. This has been a headache for researchers around the world for years, as they could never find out exactly how the stars were distributed to other galaxies, an uncertainty that led them to believe that they were distributed like the stars in our Galaxy.

“We could only see the tip of the iceberg and we knew for a long time that expecting other galaxies to look like ours was not a very good thing. However, no one has ever been able to prove that the other galaxies form different star populations. “This study allowed us to do just that, which could open the door to a deeper understanding of the formation and evolution of galaxies,” said Charles Steinhardt, an associate professor who co-authored the study.

In the study, researchers analyzed light from 140,000 galaxies using the COSMOS catalog, a large international database of more than one million light observations from other galaxies. These galaxies are distributed from the nearest to the farthest point of the universe, from which light has traveled twelve billion years before it became observable on Earth.

Huge galaxies die first

According to researchers, the new discovery will have a wide range of implications. For example, it remains unsolved because galaxies die and stop forming new stars. The new result suggests that this can be explained by a simple trend.

“Now that we are better able to decode the mass of stars, we can see a new pattern; less massive galaxies continue to form stars, while more massive galaxies stop giving birth to new stars. “This suggests an extremely global trend in the death of galaxies.”


The early universe full of star galaxies


More information:
Albert Sneppen et al, Implications of a Temperature-dependent Initial Mass Function. I. Photometric pattern adjustment, The Astrophysical Journal (2022). DOI: 10.3847 / 1538-4357 / ac695e

Provided by the Niels Bohr Institute

Reference: New discovery for distant galaxies: Stars are heavier than we thought (2022, May 25) Retrieved May 26, 2022 from https://phys.org/news/2022-05-discovery-distant-galaxies-stars- heavier.html

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