The Core Of The Milky Way Is An Extreme Place

Astronomers always like to look at incredibly violent places.  Violence, in the astronomical sense, makes for rare conditions that can explain much about our universe.  One of the violent places that astronomers love to study is the center of our Milky Way galaxy.  Now, astronomers from the Center for Astrophysics (CfA) at Harvard have come up with a new catalogue of some of the most intense areas near the galactic core.  They hope it will increase our understanding of these potential star-forming regions – and help explain why so few stars are actually formed in them.

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Astronomers Can Predict When a Galaxy’s Star Formation Ends Based on the Shape and Size of its Disk

A galaxy’s main business is star formation. And when they’re young, like youth everywhere, they keep themselves busy with it. But galaxies age, evolve, and experience a slow-down in their rate of star formation. Eventually, galaxies cease forming new stars altogether, and astronomers call that quenching. They’ve been studying quenching for decades, yet much about it remains a mystery.

A new study based on the IllustrisTNG simulations has found a link between a galaxy’s quenching and its stellar size.

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The Universe in Formation. Hubble Sees 6 Examples of Merging Galaxies

Audio narration by the author is available above

10 billion years ago, galaxies of the Universe were ablaze with the light of newly forming stars. This epic phase of history is known as  “Cosmic Noon” – the height of all star creation. Galaxies like our Milky Way aren’t creating stars at nearly the rates they were in the ancient past. However, there is a time when galaxies in the present can explode with star formation – when they collide with each other. This recently published collage of merging galaxies by the Hubble HiPEEC survey (Hubble imaging Probe of Extreme Environments and Clusters) highlights six of these collisions which help us understand star formation in the early Universe.

Newly released collage of six galaxy mergers used in the HiPEEC survey.
Top Row Left to Right: NGC 3256, 1614, 4195 Bottom Row Left To Right: NGC 3690, 6052, 34
– Credit ESA/Hubble/NASA
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This is a Simulation of the Interstellar Medium Flowing Like Smoke Throughout the Milky Way

How do stars form?

We know they form from massive structures called molecular clouds, which themselves form from the Interstellar Medium (ISM). But how and why do certain types of stars form? Why, in some situations, does a star like our Sun form, versus a red dwarf or a blue giant?

That’s one of the central questions in astronomy. It’s also a very complex one.

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Astronomers See a Newly Forming Planetary Disk That’s Continuing to Feed On Material from its Nebula

Over the last few years, astronomers have observed distant solar systems in their early stages of growth. ALMA (Atacama Large Millimeter/submillimeter Array) has captured images of young stars and their disks of material. And in those disks, they’ve spotted the tell-tale gaps that signal the presence of growing young planets.

As they ramped up their efforts, astronomers were eventually able to spot the young planets themselves. All those observations helped confirm our understanding of how young solar systems form.

But more recent research adds another level of detail to the nebular hypothesis, which guides our understanding of solar system formation.

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Planets Don’t Wait for Their Star to Form First

It looks like we may have to update our theories on how stars and planets form in new solar systems. A team of astronomers has discovered young planets forming in a solar system that’s only about 500,000 years old. Prior to this discovery, astronomers thought that stars are well into their adult life of fusion before planets formed from left over material in the circumstellar disk.

Now, according to a new study, it looks like planets and stars can form and grow up together.

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The Solar System has been Flying Through the Debris of a Supernova for 33,000 Years

An Ancient Voyage

Earth is on a journey…

While our planet orbits the Sun each year – a billion kilometers – our entire Solar System is drifting through the Milky Way Galaxy making one rotation every 225-250 million years (that means dinosaurs actually lived on the other side of the Galaxy!) Humanity has been on Earth for a small fraction of that journey, but parts of what we’ve missed is chronicled. It is written into the rock and life of our planet by the explosions of dying stars – supernova. Turns out supernovas write in radioactive ink called Iron-60.

The Crab Nebula is the remains of a Supernova which occurred about a thousand years ago and was visible on Earth recorded by ancient astronomers – C. NASA/ESA/Hubble

As the Sun travels through the Galaxy, so too do the hundreds of billions of other stars that comprise the Milky Way; all swirling and spiraling in varying directions. If you could time travel to a distant past, you’d look up and see an unfamiliar sky – different stars, different constellations, and sometimes the glow of a brilliant supernova. Stars explode in the Milky Way about once every fifty years. Given the immense size of the Galaxy at around 150,000 light years in diameter, the odds of one of those stars exploding in our backyard is low.  But while supernova happen in the Galaxy twice a century, those in close proximity to Earth, within 400 light years, do happen once every few million years. And along Earth’s epic 4.5 billion-year journey, it appears that we’ve had close encounters with supernova several times. In fact, we seem to be travelling through the fallout cloud of supernovae right now.

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Supermassive Black Holes Grew by Consuming Gas and Entire Stars

Where do they come from, those beguiling singularities that flummox astrophysicists—and the rest of us. Sure, we understand the processes behind stellar mass black holes, and how they form from the gravitational collapse of a star.

But what about the staggering behemoths at the center of galaxies, those supermassive black holes (SMBH) that can grow to be billions of times more massive than our Sun?

How do they get so big?

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The Solar System Might Not Exist if There Wasn’t a Huge Galactic Collision with the Milky Way Billions of Years Ago

The Milky Way has a number of satellite galaxies; nearly 60 of them, depedending on how we define them. One of them, called the Sagittarius Dwarf Spheroidal Galaxy (Sgr d Sph), may have played a huge role when it comes to humans, our world and our little civilization. A collision between the Milky Way and the Sgr d Sph may have created the Solar System itself.

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