Astronomers have finally found our galaxy’s missing sister
The first galaxies formed a long time ago, when our nearly 14 billion-year-old Universe was less than a billion years old. Our own galaxy, the Milky Way, is also very old: a great starlit pinwheel spinning in space that is thought to be about 13.6 billion years old, give or take 8 million years. In fact, the oldest known star in our Galaxy is 13.7 billion years old. In total, the Milky Way is believed to be home to approximately 300 billion stars. But even though our galaxy has many galactic neighbors, one of its massive starlit brethren has been lost, mysteriously disappearing billions of years ago. In July 2018, astronomers at the University of Michigan, Ann Arbor announced that they had finally found our Milky Way’s long-lost sibling. Unfortunately, the team of scientists has deduced that our present-day large nearest galactic neighbor tore apart and cannibalized this massive sister to our Milky Way two billion years ago.
Though most of it was swallowed and crushed, this huge sister galaxy left behind, as a lingering relic of its former existence, a trail of evidence revealing that it was once here. This rich trail of evidence is made up of a nearly invisible halo of stars that is larger than our Milky Way’s largest spiral neighbor, the Andromeda galaxy itself. Evidence also consists of an elusive stream of stars, as well as a mysterious and enigmatic separate galaxy called M32. Discovering and observing this partially devoured doomed galaxy will help astronomers understand how disk galaxies like our Milky Way they evolve and manage to survive large and violent mergers with other huge galaxies.
Our galaxy and its general neighborhood
The group of galaxies that includes our Milky Way is appropriately called the local group, and hosts more than 54 galaxies, most of which are relatively small in years Astronomers have predicted that sometime between 1 billion and 1 billion years from now, all the galactic constituents of the local group they will collide with each other, and these collisions and the resulting mergers will create a single huge galaxy. The center of gravity of the local group today it is situated between our Milky Way and Andromeda, and the entire group sports the impressive diameter of around 3.1 million parsecs. It also shows a binary (dumbbell) distribution. Tea local group itself is a constituent of the greater Virgo Supercluster which may, in turn, be part of the recently discovered Laniakea Supercluster.
The unfortunate decimated galaxy, dubbed M32pwas once the third largest member of the local group, after our Milky Way and Andromeda. Using supercomputer models, Dr. Richard D’Souza and Dr. Eric Bell of the University of Michigan’s Department of Astronomy were able to piece together the lingering evidence of this galactic crime, revealing all that remains of our own tragically cannibalized sister. Galaxy.
Currently, the three largest member galaxies of the local group (in decreasing order) are the Andromeda Galaxy, the Milky Way, and the Triangulum Galaxy. The larger duo of these three spiral galaxies each have their own system of orbiting satellite galaxies. Both the Milky Way and Andromeda are majestic spirals displaying starlit spiral arms rotating majestically in space. Andromeda is currently 2 million light years from our Milky Way. However, this will not always be the case. The relentless and merciless pull of powerful gravity is pulling Andromeda toward our galaxy at a staggering 250,000 miles per hour. In about 5 billion years, our Milky Way and Andromeda will collide with each other, merging to create a single huge galaxy.
Indeed, our Galaxy’s future collision with Andromeda will create an entirely new Galaxy, one that will likely display an elliptical shape, rather than the graceful starlit “pinwheel” spiral arms of its two badly disturbed galactic parents. This strange new galaxy has been given the name milkomedaeven though there will likely be no human life left on Earth to witness the huge new galaxy that will emerge from the wreckage of this monumental merger.
Such galactic wrecks may not be as violent as previously thought. These collisions have been observed in distant galaxies throughout the Cosmos, and although galaxies have been seen colliding with each other, it is not likely that two of their constituent stars would meet and merge. The splattered debris that would be left after a collision of two stars would create a huge stellar mess. The good news is that the space between the stars within a host galaxy is often huge. For this reason, violent stellar collisions rarely occur.
By contrast, the floating clouds of gas and dust that swirl together within their host galaxies will likely suffer as a result of meltdown and meltdown. That kind of unfortunate and catastrophic event will be violent and create a horrible disaster. This is because such a wreck will trigger the birth of stars within writhing, writhing clouds of gas and dust. These cool dark clouds serve as the strange cradles of bright new baby stars, being born in a dramatic, brilliant blaze of newborn glory.
Head-on galactic collisions occur over long periods of time; they can last as long as millions or billions of years, and are not over quickly for the suffering parts. However, our Milky Way has been lucky in that no violent collision with a similarly large galaxy has occurred in its entire 13.6 billion-year history, at least, not yet.
When Andromeda crashes into our Milky Way, our entire night sky will undergo a radical change. In about 3.75 billion years from now, the sky above our planet will literally be full of Andromeda as it ruthlessly approaches our Galaxy. Over the next few billion years, as a result of Andromeda’s approach, there will be bright bursts of fiery star birth lighting up Earth’s night sky.
In about 7 billion years, the sky over our planet will become even stranger and stranger. The dazzling core of the newborn. milkomeda galaxy–now our own host Galaxy– will take over the entire sky. However, the possibility that humans still exist to see this sight is remote. This is because our Sun will likely become a huge, bloated, dying red giant star roughly 5 billion years from now, and it will already have incinerated its inner planets, Mercury, Venus, and Earth, long before the collision between the two galaxies occurs.
Both our Milky Way and Andromeda are about the same age. Although the two sister galaxies are considered to be nearly identical twins, it’s a little hard to predict which of the doomed duo will suffer the most when the end comes. However, since Andromeda is slightly larger than our own galaxy, technically it will be Andromeda that will feast on our Milky Way.
A missing sister galaxy
Astronomers have long known that vast halos of nearly invisible stars surround galaxies, and that these halos contain the sad relics of smaller cannibalized galaxies. In fact, a large galaxy like Andromeda is believed to have devoured literally hundreds of its smaller companions in this Universe of galaxies that eat galaxies. For this reason, many astronomers believed that it would be a difficult task to learn the history of any one of these unfortunate little galaxies in particular.
However, the team of astronomers using new supercomputer simulations were able to come up with a new understanding. The scientists found that even though Andromeda gobbled up a large number of companion galaxies, most of the stellar inhabitants of that galaxy’s faint outer halo were the unfortunate children of a single, great, shattered galaxy.
“It was a ‘eureka’ moment. We realized we could use this information from Andromeda’s outer stellar halo to infer the properties of the largest of these shredded galaxies,” said study lead author Dr D’Souza, in a statement dated July 23, 2018. Press release from the University of Michigan. Dr. D’Souza is a postdoctoral researcher at the University of Michigan.
“Astronomers have been studying the local group–the Milky Way, Andromeda and their companions–for so long. It was shocking to realize that the Milky Way had a big brother, and we never knew,” said co-author Dr. Bell in the same paper. Press release. Dr. Bell is a professor of astronomy at the University of Michigan.
This unfortunate sister galaxy to our Milky Way, M32pmercilessly torn apart by the voracious Andromeda galaxy, it was at least 20 times larger than any galaxy that merged with the Milky Way over the course of its more than 13 billion years of existence. M32p would have been quite massive, and would probably have been the third largest galaxy in the local group, after Andromeda and our Milky Way, if it had not been crushed and consumed by Andromeda.
This new study could also solve an intriguing mystery: the formation of the perplexing Andromeda system. M32 galaxy satellite. Astronomers now suggest that the compact and dense M32 it is really the surviving central heart of our Milky Way’s long lost sister. The team of astronomers compares M32 to the stone of a plum.
“M32 it’s an oddball. While it looks like a compact example of an ancient elliptical galaxy, it actually has many young stars. It is one of the most compact galaxies in the Universe. There is no other galaxy like it,” Dr. Bell noted on July 23, 2018. Press release from the University of Michigan.
The new research may change the currently most accepted scientific understanding of the way galaxies evolve. Astronomers realized that the Andromeda disk had managed to survive a collision with a massive galaxy. This impact would challenge the traditional view that such large interactions would invariably destroy the ordered disks of spirals, thus creating only elliptical galaxies.
The moment of impact may also shed new light on the thickening of Andromeda’s disk, as well as a mysterious burst of bright stellar birth that occurred around two billion years ago. This finding was reached independently by a team of French astronomers in early 2018.
“The Andromeda Galaxy, with a spectacular burst of star formation, would have looked very different 2 billion years ago. When I was in graduate school, I was told that understanding how the Andromeda Galaxy and its satellite galaxy M32 formed would go a long way toward unraveling the mysteries of galaxy formation,” explained Dr. Bell on July 23, 2018. Press release from the University of Michigan.
The good news is that this study can also be used for other galaxies. This would allow astronomers to measure their most massive past galaxy mergers. Armed with this new knowledge, scientists can continue to untangle the intricate and complicated tapestry of cause and effect that triggers galaxy growth, as well as learn about the effect of mergers on the galaxies that must undergo through them.