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Astronomers Discover New Type Of ‘Freak Star’ Formed By Rare Stellar Event 

Astronomers have discovered a new type of “freak star” covered in helium-burning ashes, which is believed to have formed by a rare stellar merger event. 

A German team of experts were looking for “hot stars” in Arizona using a Large Binocular Telescope when they came across two stars with unusual properties. The stars are known as PG1654+322 and PG1528+025, and are about 10,000 and 25,000 light years away from Earth within our galaxy. 

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The experts reported “while normal star surfaces are composed of hydrogen and helium, these newly-found stars are covered in great quantities of carbon and oxygen – the by-product of helium nuclear fusion. Astonishingly high abundances of both carbon and oxygen – each accounting for around 20 percent of surface composition for both stars.”

“Stars that are covered in this much carbon and oxygen usually have finished nuclear fusion reactions that take place at their core. However, temperatures and diameters of the two newly-discovered stars indicate that helium nuclei continue to fuse inside them – an unprecedented finding,” the experts reported. 

The research was conducted by a team of astronomers, led by Professor Klaus Werner of the University of Tübingen, and published in Monthly Notices of the Royal Astronomical Society

“We normally expect stars with the chemical surface composition of the stars discovered to have completed the helium fusion in their centers and to be in the final stages of becoming white dwarfs,” said Professor Werner. 

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“These new stars are a severe challenge to our understanding of stellar evolution. Carbon and oxygen are normal in old stars that are fusing helium, but only in their cores. So it is extremely unusual to see them in large quantities at their surface.” 

“We believe that the stars discovered by our German colleagues were formed by a very rare type of merging between two white dwarfs,”said Miller Bertolami, author of a second companion paper by astronomers, also published in Monthly Notices of the Royal Astronomical Society

“White dwarfs are the remnants of larger stars that have exhausted their nuclear fuel, and are typically very small and dense,” he explained. 

There are currently no stellar evolutionary models that can fully explain how exactly these new stars were formed and why, which could create a whole new binary for scientists to work off of when it comes to new star discoveries. 

The two stars will continue to be monitored as a part of the larger-scale research the team is doing to track down short-lived, hot stars. This research should also help the team better understand what exactly these stars endured in order to evolve into what they are currently.

Galaxy

For The First Time Ever, Astronomers Were Able To Watch As A Distant Galaxy ‘Dies’ 

For the first time in history, astronomers were able to witness the previously unknown phenomenon of a galaxy’s life coming to an end. Galaxies die when the stars that live within them stop forming. 

Using the Atacama Large Millimeter/submillimeter Array of telescopes in Chile scientists were able to watch as a distant galaxy ejected half of the gas it uses to form stars. The galaxy is specifically known as ID 2299, and the light emitted from the stars within this galaxy took about nine billion years to reach Earth.

Based on this timing, astronomers determined that they’re currently witnessing cosmic events that occurred when the universe was only 4.5 billion years old; the universe is thought to be 14 billion years old for context. 

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The galaxy is thought to be losing around 10,000 suns-worth of gas per year. This is significant because that gas is what’s needed for the galaxy to produce new stars. So far astronomers believe ID2299 has lost about 46% of its cold gas, however, the galaxy is still able to quickly form stars at rates greater than what we experience in our own Milky Way galaxy. 

Since ID2299 is still able to successfully produce stars, it’s likely that it won’t die for another few tens of millions of years. Annagrazia Puglisi, lead study researcher and postdoctoral research associate from Durham University in the UK and the Saclay Nuclear Research Center in France, spoke to the press after publishing the study in the journal of Nature Astronomy

“This is the first time we have observed a typical massive star-forming galaxy in the distant Universe about to ‘die’ because of a massive cold gas ejection.” 

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According to Puglisi, it’s also possible that ID2299’s demise is the result of a collision with another galaxy. Astronomers observed a large stream of gas and stars that typically only forms when two galaxies come together in a collision, and normally these streams are too far and faint to be seen, however, the scientists ability to see this tail means that the galaxy was likely formed by some sort of collision. 

 If a collision is what is causing this galaxy’s demise, astronomers will need to reconsider existing theories regarding the life cycle of stars and their formation at the end of a galaxy’s “life.” Previous theories claimed that the winds created by star formations would combine with active black holes at the center of a galaxy, which would thus send out materials needed to form stars.

“Our study suggests that gas ejections can be produced by mergers and that winds and tidal tails can appear very similar. This might lead us to revise our understanding of how galaxies ‘die,’” said Emanuele Daddi, study coauthor and astronomer at the Saclay Nuclear Research Centre in France. 

Astronomers were actually working on a survey regarding cold gas in distant galaxies when they noticed the tidal tail of ID2299 and realized just what they were witnessing. Future observations of the galaxy will likely reveal more about the process of gas being ejected from galaxies and how it impacts star formation, but in the meantime, astronomers are celebrating the fact that they witnessed a cosmic event that they’ve only theorized about in the past.

Galaxy

Scientists Discover New Galaxy That ‘Only’ Took 500 Million Years To Form 

In general, galaxies take a very long time to form, and when I say that, I mean billions of years. Galaxies typically build up very slowly and take that time to acquire the bulk of what makes them so vast and large. However, recently scientists discovered a galaxy that seems to have appeared in our universe when it was only 1.8 billion years old. 

While 1.8 billion years seems like an unfathomable amount of time to understand, just know that the Milky Way galaxy, which our planet is currently in, took around 13.6 billion years to fully form to be habitual for life. This galaxy is thought to have formed stars at rates hundreds of times greater than the Milky Way. 

In less than 500 million years, this galaxy has managed to form over 200 billion stars. Scientists are viewing this as one of the universe’s “greatest speed runs,” in terms of creating new galaxies. Galaxies start as very small nuggets of stars that take hundreds of millions, and even billions, of years to merge with one another and begin to grow. 

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This process is called the “hierarchical model,” and is one of the main theories used in the science community to explain how galaxies grow over cosmic time. Astronomers based at the University of Arizona were using the facilities Large Binocular Telescope when they spotted the “oddball” that was previously not in other scans. 

The galaxy is currently called C1-23152, and is billions of light years away from Earth. Its light has been reportedly traveling for over 12 billion years, making it one of the youngest galaxies on the cosmic scene due to the fact that it appeared when our universe was only 1.8 billion years old. 

Scientists were able to determine that the galaxy grew from basically nothing throughout the course of 500 million years by measuring the age, metal content, and velocity of the stars that are in C1-23152.

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At its peak of formation the galaxy was forming stars by the hundreds every year, averaging a few stars every single day. This rate of creation is pretty astounding, and often unheard of in terms of galaxy formation. For some perspective, our Milky Way Galaxy currently produces only a handful of stars every year.

C1-23152 is now known as a massive superstar galaxy after years of being a little cosmic speck in the corner of the telescope. Scientists are still trying to determine how the galaxy was able to grow at such an exponential rate. The usual hierarchical method doesn’t really apply here due to the speed of the galaxy’s formation alone. 

Astronomers at the moment believe that C1-23152’s creation was actually the result of a massive cosmic accident. They believe that two giant gas clouds located in the early universe collided and triggered a round of rapid star formation that was able to persist through hundreds of millions of years to form an entire galaxy. 

Scientists will continue to monitor C1-23152 and any other galaxy that appears to have formed at a similar rate. The hope is gather a greater understanding in general over how galaxies are formed beyond just the hierarchical method that scientists have been using for decades now.

Milky Way

Scientists Have Discovered a Hypervelocity Star Heading Out Of The Milky Way

A star has been seen making its way out of the Milky Way at a speed of 3.7 million miles per hour, the equivalent of 1056 miles per second or ten times faster than the majority of the stars in the Milky Way, including the sun. However it is widely believed it will take a further 100 million years before it actually makes its way out of the Milky Way and will then spend eternity roaming around intergalactic space.

Hypervelocity stars were discovered by astronomers in 2005 although numbers are still low, with fewer than 30 found in the last 14 years. Named S5-HVS1, the star has made its way to the constellation of Grus, which is at a distance of just over 29,000 light-years.

University of Oxford astronomer Dr. Douglas Boubert confirmed that the S5-HVS1’s velocity is so high it will ‘inevitably leave the Galaxy and never return,’ while Carnegie Mellon University researcher Dr. Sergey Koposov exclaimed ‘this is super exciting, as we have long suspected that black holes can eject stars with very high velocities’.

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It is the first time a black hole has thrown a star out of the galaxy since the act was predicted 30 years ago via the Hills mechanism suggested by astronomer Jack Hills, and Dr. Ting Li from Carnegie Observatories and Princeton University was quick to confirm that ‘seeing this star really is amazing as we know it must have formed in the galactic center, a place very different to our local environment.’

The Southern Stellar Stream Spectroscopic Survey (S5) are responsible for the discovery thanks to the data collected from a 3.9-m Anglo-Australian Telescope alongside ESA’s Gaia satellite. The astronomers were then able to understand the star’s journey out of the Milky Way’s center.

S5’s main goal scientifically is to probe the stellar streams, however they were able to provide some of their resources to look around the Milky Way to see if there was anything interesting. Using this technique they were able to discover the star and Lowell Observatory’s Dr. Kyler Kuehn is hopeful they will ‘find even more’.

The team’s paper was published in the Monthly Notices of the Royal Astronomical Society.