Centaurus A

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Only 11 million light-years away, Centaurus A is the closest active galaxy to planet Earth. Spanning over 60,000 light-years, the peculiar elliptical galaxy, also known as NGC 5128, is featured in this sharp color image. Centaurus A is apparently the result of a collision of two otherwise normal galaxies resulting in a fantastic jumble of star clusters and imposing dark dust lanes. Near the galaxy’s center, left over cosmic debris is steadily being consumed by a central black hole with a billion times the mass of the Sun. As in other active galaxies, that process likely generates the radio, X-ray, and gamma-ray energy radiated by Centaurus A.

Credit: Tim Carruthers

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NGC 6520

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NGC 6520 is an open star cluster located about 5,500 light years away towards the constellation Sagittarius. It is about 10 light years across. The bright blue stars are only a few million years old, much younger than our Sun.

Blocking the light of NGC 6520 is Barnard 86, an absorption nebula and molecular cloud. It contains is filled with thick dust that obscures the star cluster. Surrounding the cluster and nebula in this image is part of the dense starscape of our own Milky Way.

Image and information from NASA.

A colorful gathering of middle-aged stars

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The bright star cluster NGC 3532 covers an area of the sky that is almost twice the size of the Full Moon.

The MPG/ESO 2.2-meter telescope at the European Southern Observatory’s (ESO) La Silla Observatory in Chile has captured a richly colorful view of the bright star cluster NGC 3532. Some of the stars still shine with a hot bluish color, but many of the more massive ones have become red giants and glow with a rich orange hue.

NGC 3532 is a bright open cluster located some 1,300 light-years away in the constellation Carina the Keel. It is informally known as the Wishing Well Cluster as it resembles scattered silver coins that have been dropped into a well. It is also referred to as the Football Cluster, although how appropriate this is depends on which side of the Atlantic you live. It acquired the name because of its oval shape, which citizens of rugby-playing nations might see as resembling a rugby ball.

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What is the Multiverse, and why do we think it exists? 

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[…] Our observable Universe caps out at about 92 billion light-years in diameter, less than a thousand times as large in all directions as our previous scale. It contains some 1080 atoms, clumped together in maybe a trillion galaxies, each with typically hundreds of billions of stars. But one of the most remarkable things about the Big Bang is that all of this, some 13.8 billion years ago, was once contained in a very small region of space, a region much smaller than our Solar System is today!

The thing that you might immediately wonder is whether there’s more Universe beyond the part that’s observable to us today, and — if so — how far does it go on? And what does it look like? And what are the physical laws in that part of the Universe?

Based on our observations of everything we’ve been able to see, from stars to galaxies to the leftover glow from the Big Bang to the matter in intergalactic space, we can learn some amazing things.

The part of the Universe that’s unobservable to us — filled with more planets, stars, galaxies, clusters and voids — is at least 150 times the size of the part that is observable! The fundamental constants look to be the same at all locations and at all times in our observable Universe, and our true Universe appears to be at least many millions of times the volume of the part we can see.

All of this, too, began in the same Big Bang that created all the matter-and-radiation in our hot, dense expanding Universe some 13.8 billion years ago. But that wasn’t even the very beginning.

Read the full article by Ethan Siegel

Four new Galaxy Clusters take researchers further back in time

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Four unknown galaxy clusters each potentially containing thousands of individual galaxies have been discovered some 10 billion light-years from Earth.

An international team of astronomers, led by Imperial College London, used a new way of combining data from the two European Space Agency satellites, Planck and Herschel, to identify more distant galaxy clusters than has previously been possible. The researchers believe up to 2,000 further clusters could be identified using this technique, helping to build a more detailed timeline of how clusters are formed.

Galaxy clusters are the most massive objects in the universe, containing hundreds to thousands of galaxies, bound together by gravity. While astronomers have identified many nearby clusters, they need to go further back in time to understand how these structures are formed. This means finding clusters at greater distances from the Earth.

The light from the most distant of the four new clusters identified by the team has taken over 10 billion years to reach us. This means the researchers are seeing what the cluster looked like when the universe was just three billion years old.

Lead researcher Dr. David Clements, from the Department of Physics at Imperial College London, explains: “Although we’re able to see individual galaxies that go further back in time, up to now, the most distant clusters found by astronomers date back to when the universe was 4.5 billion years old. This equates to around nine billion light-years away. Our new approach has already found a cluster in existence much earlier than that, and we believe it has the potential to go even further.”

The clusters can be identified at such distances because they contain galaxies in which huge amounts of dust and gas are being formed into stars. This process emits light that can be picked up by the satellite surveys.

Galaxies are divided into two types: elliptical galaxies that have many stars, but little dust and gas; and spiral galaxies like our own, the Milky Way, which contain lots of dust and gas. Most clusters in the universe today are dominated by giant elliptical galaxies in which the dust and gas has already been formed into stars.

“What we believe we are seeing in these distant clusters are giant elliptical galaxies in the process of being formed,” says Dr. Clements.

Observations were recorded by the Spectral and Photometric Imaging Receiver (SPIRE) instrument as part of Herschel Multi-tiered Extragalactic Survey (HerMES). Seb Oliver, Head of the HerMES survey, said: “The fantastic thing about Herschel-SPIRE is that we are able to scan very large areas of the sky with sufficient sensitivity and image sharpness that we can find these rare and exotic things. This result from Dr. Clements is exactly the kind of thing we were hoping to find with the HerMES survey.”

The researchers are among the first to combine data from two satellites that ended their operations last year: the Planck satellite, which scanned the whole sky, and the Herschel satellite, which surveyed certain sections in greater detail. The researchers used Planck data to find sources of far-infrared emission in areas covered by the Herschel satellite, then cross referenced with Herschel data to look at these sources more closely. Of sixteen sources identified by the researchers, most were confirmed as single, nearby galaxies that were already known. However, four were shown by Herschel to be formed of multiple, fainter sources, indicating previously unknown galaxy clusters.

The team then used additional existing data and new observations to estimate the distance of these clusters from Earth and to determine which of the galaxies within them were forming stars. The researchers are now looking to identify more galaxy clusters using this technique, with the aim of looking further back in time to the earliest stage of cluster formation.

The research involved scientists from the UK, Spain, USA, Canada, Italy and South Africa. It is published in the Monthly Notices of the Royal Astronomical Society and was part funded by the Science and Technology Facilities Research Council and the UK Space Agency