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We’re Living Next Door To A Cannibal Galaxy Whose Violent Past Has Been Revealed

We're Living Next Door To A Cannibal Galaxy Whose Violent Past Has Been Revealed 86

A study of the small galaxies swallowed by our nearest large galactic neighbor has revealed something of how galaxies grow. In the process, it has hinted at something that, if true, would change the way we see the universe in profound ways.

All galaxies, including our own Milky Way, grow by consuming smaller ones. Inevitably, the nearest large galaxy to our own, M31, also known as Andromeda, has eaten many small neighbors. Our first insight into the nature of these events is useful because Andromeda and the Milky Way are on course to meet. That’s 4 billion years away, but it’s good to be prepared.

Dr Dougal Mackey of the Australian National University and Professor Geraint Lewis from the University of Sydney analyzed streams of stars within Andromeda’s halo and identified some as the remnants of galaxies, even gaining approximations of when this occurred. Rather than a steady process, they identified two bursts separated by billions of years. The galaxies in the two rounds arrived at right angles to each other and maintained that motion even after being pulled apart.

“We are cosmic archaeologists, except we are digging through the fossils of long-dead galaxies rather than human history,” Lewis said in a statement.

Mackey told IFLScience the consumed galaxies contained globular clusters, groups of stars bound so closely together that only the most powerful gravitational disruptions pull them apart.

Individual stars in Andromeda’s halo are usually too distant and faint for us to track their movements, but the clusters are a different matter, allowing the pair to identify in Nature the streams whose shared movements pin them as past galaxies.

“Once you get below a certain mass, galaxies don’t contain globular clusters,” Mackey said, so the smallest are currently untraceable. However, he added that the contribution of these to Andromeda’s growth was minor.

One day, Andromeda will swallow the Milky Way as well. However, Mackey acknowledged to IFLScience this will be a very different process. The galaxies Andromeda has eaten up until now have masses a tenth of its total at most, usually much smaller. The Milky Way, on the other hand, is at least half Andromeda’s size.

The merger of the two will destroy the spiral structure of each, creating an egg-like elliptical galaxy. By then, the Sun will have burned the Earth beyond recognition, but if humanity somehow survives elsewhere, consequences will be limited. Our view of the night sky will change utterly, but the space between the stars is so great that even when stars from Andromeda become mixed among our nearest neighbors, it is unlikely any will pass close enough to disrupt orbits within the inner solar system.

One feature of the pair’s work is still tentative but could turn out to be awe-inspiring. Around a decade ago astronomers noticed a curious pattern in the dwarf galaxies that surround Andromeda. Around half these galaxies orbit in a specific plane, something astronomers had not expected and struggled to explain. We now know this pattern is unstable, and can neither have been in place for a long time (astronomically speaking) or have lasted that far into the future.

This study found that some of the swallowed galaxy remnants conform to the same pattern, but surprisingly, it is the much older set that do this, rather than the more recent arrival. This suggests these long-lost galaxies also once lay in a similar plane, indicating an abiding underlying structure to the local area of the universe. The most likely explanation is the universe is made up of a web of dark matter filaments and Andromeda lies on one of these, with gravity so powerful it aligns the movement of clusters of small galaxies.

Source www.iflscience.com

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Space

KOI-5Ab, the curious planet that orbits in a system of three suns

KOI-5Ab, the curious planet that orbits in a system of three suns 99
Photo: (Caltech / R. Hurt (IPAC))

To us, the Sun alone seems perfectly normal, but our solar system is actually a strange exception.

Most stars in the Milky Way galaxy have at least one companion star. In a system 1,800 light-years away, astronomers have finally confirmed the existence of a gas giant planet orbiting stars in a triple star system.

Called KOI-5, the system is located in the constellation Cygnus, and the exoplanet was confirmed ten years after it was first detected by the Kepler space telescope.

In fact, the planet – now known as KOI-5Ab – was discovered by Kepler when it began operations back in 2009.

“KOI-5Ab was dropped because it was difficult and we had thousands of other candidates,” astronomer David Siardi of NASA’s Exoplanet Science Institute said.

“There were lighter dives than the KOI-5Ab, and every day we learned something new from Kepler, so the KOI-5 was almost forgotten.”

Exoplanet hunters tend to avoid the complexities of multi-star systems; of the more than 4,300 exoplanets confirmed to date, less than 10 percent are multi-star systems, although such systems dominate the galaxy. As a result, little is known about the properties of exoplanets in multi-star systems compared to those orbiting a lone star.

After Kepler’s discovery, Chardy and other astronomers used ground-based telescopes such as the Palomar Observatory, Keck Observatory, and the Gemini North Telescope to study the system. By 2014, they had identified two companion stars, KOI-5B and KOI-5C.

Scientists were able to establish that the planet KOI-5Ab, is a gas giant that is about half the mass of Saturn and 7 times the size of Earth, and is in a very close five-day orbit around KOI-5A. KOI-5A and KOI-5B, both of roughly the same mass as the Sun, form a relatively close binary system with an orbital period of about 30 years.

KOI-5Ab, the curious planet that orbits in a system of three suns 100

A third star, KOI-5C, orbits the binary system at a much greater distance, with a period of about 400 years – slightly longer than Pluto’s 248-year orbit.

“By studying this system in more detail, perhaps we can understand how planets are created in the universe.”

The discovery was announced at the 237th meeting of the American Astronomical Society.

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Space

Why the universe does not fit into science

Why the universe does not fit into science 101
Photo: YouTube

Science can be compared to an artist painting what he has never seen, or to a writer describing other people’s travels: objects that he has never seen, places where he has never been. Sometimes such scientific “arts” turn out to be beautiful and interesting, but most of them will forever remain only theories, because they are beyond human capabilities.

In fact, science has the right only to speculate: how our universe appeared, how old it is, how many stars and other objects it contains.

Universe model

Why the universe does not fit into science 102

How many stars are there in the sky?

With an unarmed eye, a person can see about nine thousand stars in the sky in one cloudless and moonless night. And armed with binoculars or a telescope, much more – up to several million. However, this is much less than their true number in the universe. Indeed, only in our one galaxy (the Milky Way) there are about 400 billion stars. The exact amount, of course, is not known to science. And the visible universe contains about 170 billion galaxies.

It is worth clarifying that scientists can see the universe 46 billion light years deep in all directions. And the visible (observable) universe includes the space accessible to our eyes from the moment of the Big Explosion. In other words, only this (accessible to human perception) space science refers to our universe. Science does not consider everything that follows.

It is believed that there are supposedly a ceptillion (10 to 24 degrees) stars in our universe. These are theoretical calculations based on the approximate size and age of the universe. The origin of the universe is explained by the Big Bang theory. This is why the universe is constantly expanding and the more time passes, the more complex the universe and its components become.

Why the universe does not fit into science 103

It is not entirely correct to consider and perceive this scientific theory “head-on”. Scientists always claim that that explosion was not exactly an explosion, and the point that exploded was not the only one. After all, it was everywhere, because space did not exist then. And in general – everything happened quite differently from what is described in the Big Bang theory, but all other descriptions of the origin of the universe are even more incredible and inaccurate.

Separate but interconnected

That which is beyond the reach of human perception is usually discarded by science, or recognized as non-existent. Recognizing one thing, science does not want to recognize the existence of the other, although everything in our world is interconnected and is not able to exist separately – by itself.

Each object of the universe is a part of it much more than an independent, separate object.

Any person, like any material object of our world, consists of components: organs, cells, molecules, atoms. And each of its constituent parts can represent the whole world. Separate, and at the same time connected with all the others.

However, science, as a rule, perceives all the components of the universe – people, animals, plants, objects, the Earth, the Sun, other planets and stars – as separate subjects, thereby limiting itself.

Why the universe does not fit into science 104

Even what is considered the visible universe, one of the atoms of which could be called our solar system, is not subject to the boundaries of human perception. But perhaps the atom is an exaggeration, and our solar system is not even an atom, but one of its elements!

How, being so far from the truth, can one reason about something with the degree of probability with which science tries to reason about the origin of the universe?

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Space

An unexplained wobble shifts the poles of Mars

An unexplained wobble shifts the poles of Mars 105

The red planet sways from side to side like a whirligig when it loses speed. The new study allowed scientists to notice that the poles of Mars deviate slightly from the axis of rotation of the planet. On average, they move 10 cm from the center with a period of 200 days.

Such changes are called the Chandler Oscillations  – after the American astronomer Seth Chandler, who discovered them in 1891. Previously, they were only seen on Earth. It is known that the displacement of the poles of rotation of our planet occurs with a period of 433 days, while the amplitude reaches 15 meters. There is no exact answer why this is happening. It is believed that the fluctuations are influenced by processes in the ocean and the Earth’s atmosphere.

Chandler’s wobbles on Mars are equally perplexing. The authors of the study discovered them by comparing data from 18 years of studying the planet. The information was obtained thanks to three spacecraft that orbit the Red Planet: Mars Odyssey, Mars Reconnaissance Orbiter and Mars Global Surveyor. 

Since Mars has no oceans, it is likely that the Red Planet’s wobbly rotation is due to changes in atmospheric pressure. This is the first explanation that researchers have shared. In the future, there should be new details about the fluctuations that have so interested the scientific community.

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