Distant Galaxies Challenge Our Understanding of Star Formation

Real Clear Science ^ | 22 Jan, 2018 | Marie Martig

[MtnClimber]

The most massive galaxies in our neighbourhood formed their stars billions of years ago, early in the history of the universe. At the present day, they produce very few new stars. Astronomers have long believed that is because they contain very little gas – a key ingredient necessary to produce stars. But our new study, published in Nature Astronomy, is now challenging this long held view.

Through probing the extreme environments of faraway massive galaxies, we can learn not only about their evolution and the history of the universe, but most importantly about the fundamental processes regulating the formation of stars. Given that stars produce most of the different types of atoms in our bodies and the world around us, understanding how they were formed is essential if we are to know where we came from.

Galaxies exist in two main types: disc and elliptical. Disc galaxies, including the Milky Way, are flat and contain large reservoirs of gas that they use to continually form stars. Elliptical galaxies are massive, round and stopped forming stars long ago. Most theories assume that at some point elliptical galaxies lost their gas reservoirs, which caused the rate of star formation to drop.

Distant light Our team investigated whether there are other ways in which distant, elliptical galaxies could have lost their ability to form stars. Distance to galaxies are measured by how bright its stars are, in light years (defined as how long it takes the light to reach us in one year). As it takes so long for the light from these faraway galaxies to reach us, we can work out that they appear to us as they were 10 billion years ago.

[MtnClimber]

Spiral galaxies are more planar so the gas would be more concentrated. An elliptical galaxy would not have the gravitational distribution to concentrate gas.

[norwaypinesavage]

"Elliptical galaxies are massive, round and stopped forming stars long ago."

If they are round, why are they named 'elliptical'?

[MtnClimber]

I noticed that too. Some artifact of General Relativity, no doubt.

[PIF]

... understanding how they were formed is essential if we are to know where we came from.

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Since this solar system seems to be an anomalous, finding out how this system was formed will not be found by comparison to the majority of other systems.

And certainly will now tell anyone where we came from -

[mlo]

“So why is that? Nine years ago, I predicted this possibility from numerical simulations I had run as a PhD student. I found that in disc galaxies, the gravitational pull of the stars helps the gas to collapse to form new stars. In contrast, the gas in elliptical galaxies feels a weaker pull from the stars and does not collapse so easily. It is fascinating that the global morphology of a galaxy can control what happens at the smallest scales.”

[mlo]

"If they are round, why are they named 'elliptical'?"

A circle is a special case of an ellipse.

[buckalfa]

Astronomy and the cosmos always are interesting, but this story sounds more like a plea for money

[dangus]

For that matter, eliptical galaxies are also not necessarily massive. Many of the small neighbors of the mliky way are eliptical.

[MtnClimber]

And I think elliptical galaxies could primarily be formed by merging spiral galaxies with different axial planes. Just like what will happen between the Milky Way and Andromeda in about 3 billion years.

[lagrange point1]

Most round ones not seen from the perpendicular appear as ellipses from earth.

LP

[sargon]

Distance to galaxies are measured by how bright its stars are, in light years (defined as how long it takes the light to reach us in one year).

Orly?

[norwaypinesavage]

"Most round ones not seen from the perpendicular appear as ellipses from earth."

So do ellipses.

[SgtHooper]

Has this been cleared through Bill Nye?

[MtnClimber]

Has this been cleared through Bill Nye?

No. He would say that supernovas that destroy all planets near them are caused by Trump, Global warming and rascism.

[SunkenCiv]

Thanks MtnClimber. This one looks like it will be of interest to my old version of the APoD list, so here goes.

[SunkenCiv]

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[SunkenCiv]

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[doorgunner69]

A circle is a special case of an ellipse.

Scary how long ago I learned that. A good radome vendor had published a book: "Conic Sections" that had great info on how many curves were obtained from conic sections. Lost my copy decades ago. Name of Wally Downs, was Hugh Downs brother. Not real sure who Hugh was, but do recall him telling me that.