A census of 140,000 galaxies has revealed a surprising fact about their stars

How many types of stars live in other galaxies? It seems like a simple question, but it’s hard to define because astronomers have a hard time estimating star clusters in distant galaxies.

A team of astronomers has now completed a count of more than 140,000 galaxies and found that more distant galaxies tend to have heavier stars.

star count

Although astronomers lack a complete count of the hundreds of billions of stars in the Milky Way, they have sampled enough of them to get a good treatment of the population.

We know, roughly, how many small dwarf stars, how many intermediate Sun-like stars, and how many giant stars there are.

But repeat this exercise for other galaxies Too difficult. Most galaxies are too far from identifying and measuring the individual stars within them.

We only see their brightest and heaviest stars, and we have to guess the smaller constellations.

Astronomers usually assume that the demographics of a distant galaxy roughly matches what we see in the Milky Way because, on average, galaxies shouldn’t be too different from each other.

Recently, a team of astronomers used the COSMOS catalog to study 140,000 individual galaxies, Develop techniques to estimate the number of stars in each one.

The research was conducted at the Center for Cosmic Dawn (DAWN), an international center for basic research in astronomy with support from the Danish National Research Foundation. DAWN is a collaboration between the Niels Bohr Institute at the University of Copenhagen and DTU Space at the Technical University of Denmark.

The fate of heavier galaxies in the future

“We’ve only been able to see the top of the iceberg and have known for a long time that expecting other galaxies to look like our own was not a particularly good assumption. However, no one has been able to prove that. Galaxies form different groups of stars. This study allowed us to do This may open the door to a deeper understanding of the formation and evolution of galaxies.” Says Associate Professor Charles Steinhardt, co-author of study.

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The team found that, on average, distant galaxies tend to have stars larger than the Milky Way. On the other hand, nearby galaxies were relatively similar to our own.

“The mass of stars tells astronomers a lot. If you change the mass, you also change the number of supernovae and black holes that arise from massive stars. As such, our result means that we will have to revise many things we once assumed, because distant galaxies look very different from our own,” Says Albert Sneben, a graduate student at the Niels Bohr Institute and first author of the study.

This work has several important implications.

First, astronomers can no longer assume the existence of a uniform group of stars when looking at distant galaxies, which represent smallest galaxies to appear in the universe. It also forces us to rethink How do galaxies evolve? over billions of years.

“Now that we are better able to decipher 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 indicates a marked global trend in galaxies dying,” Concludes Snipin.

This article was originally published by universe today. Read the original article.

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