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A Mysterious, [ Giant 'Blinking' Object ] Has Been Detected Near Our (Ga...

Prabhu TL July 09, 2021

A Mysterious, Giant 'Blinking' Object Has Been Detected Near Our Galaxy's Center

There's something strange near the galactic center.

Some 25,000 light-years from Earth, astronomers have found a weird star that almost blinked out of existence for several months before reappearing.

Astronomers believe the star, named VVV-WIT-08, could belong to a new class of star - giant beasts over 100 times the Sun that are eclipsed by a mysterious orbiting body once every few decades.

Stars with peculiar dimming signatures are an endless fascination. Although space is mostly relatively empty, it stands to reason that, with all the stuff out there, some of it will line up in such a way that stars are dimmed from our terrestrial perspective from time to time.

It's not always easy to tell what that stuff is, though. A giant planet? Space dust? Debris from a disrupted object? A cosmic dragon?

The case of VVV-WIT-08 is a doozy. Although other stars have exhibited similar dips in light, none have been so deep. The culprit, astronomers think, could be another star or planet, surrounded by a thick, opaque disk of dust on a long orbit around VVV-WIT-08, that covers the star completely when it passes in front of our view.

"It's amazing that we just observed a dark, large and elongated object pass between us and the distant star and we can only speculate what its origin is," said astronomer Sergey Koposov from the University of Edinburgh in Scotland.

The model of an orbital companion with a giant disk isn't without precedent. One famous, well-known example is Epsilon Aurigae, a supergiant star and with a disk-shrouded companion on a 27-year orbit that dims the star by about 50 percent for up to 730 days.

Then there's the system TYC 2505-672-1, a red giant star with a dusty companion on a 69-year orbit that eclipses the star for a period of 3.5 years.

The survey that picked up VVV-WIT-08 (the "WIT" stands for "what is this?" because astronomers are great like that), the VISTA Variables in the Via Lactea (VVV) survey, picked up a couple of other candidates that seemed to exhibit the same behavior. Because the data on those stars aren't as complete as the data for VVV-WIT-08, they are yet to be described.

We know the star's peculiarity isn't an error, though. The dimming was also observed by the Optical Gravitational Lensing Experiment using the Warsaw Telescope in Chile, which means it wasn't a glitch (although it would have to be a very strange sort of glitch).

The data show that the dimming event lasted for approximately 200 days, with a nearly symmetrical light curve, quenching the star's light by up to 97 percent. The density of objects required in that region of space for the chance alignment of two random bodies is much higher than observed, so the team believes the two objects are gravitationally bound.

The orbital period is unknown, but it has to be at least a few decades, according to mathematical modelling.

And the discovery suggests such systems may not be all that uncommon.

"There are certainly more to be found, but the challenge now is in figuring out what the hidden companions are, and how they came to be surrounded by discs, despite orbiting so far from the giant star," said astronomer Leigh Smith of the University of Cambridge.

"In doing so, we might learn something new about how these kinds of systems evolve."

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For The First Time Ever, Astronomers Detected Planets Outside Our Galaxy in 2018

Prabhu TL December 23, 2018

In an incredible world first, astrophysicists detected multiple planets in another galaxy earlier this year, ranging from masses as small as the Moon to ones as great as Jupiter.

Given how difficult it is to find exoplanets even within our Milky Way galaxy, this is
no mean feat. Researchers at the University of Oklahoma achieved this in February thanks to clever use of gravitational microlensing.

The technique, first predicted by Einstein's theory of general relativity, has been used to find exoplanets within Milky Way, and it's the only known way of finding the smallest and most distant planets, thousands of light-years from Earth.

As a planet orbits a star, the gravitational field of the system can bend the light of a distant star behind it.

We know what this looks like when it's just two stars, so when a planet enters the mix, it creates a further disturbance in the light that reaches us - a recognisable signature for the planet.

So far, 53 exoplanets within the Milky Way have been detected using this method. To find planets farther afield, though, something a little bit more powerful than a single star was required.

Oklahoma University astronomers Xinyu Dai and Eduardo Guerras studied a quasar 6 billion light-years away called RX J1131-1231, one of the best gravitationally lensed quasars in the sky.

The gravitational field of a galaxy 3.8 billion light-years away between us and the quasar bends light in such a way that it creates four images of the quasar, which is an active supermassive black hole that's extremely bright in X-ray, thanks to the intense heat of its accretion disc.

Using data from NASA's Chandra X-ray observatory, the researchers found that there were peculiar line energy shifts in the quasar's light that could only be explained by planets in the galaxy lensing the quasar.

It turned out to be around 2,000 unbound planets with masses ranging between the Moon and Jupiter, between the galaxy's stars.

"We are very excited about this discovery. This is the first time anyone has discovered planets outside our galaxy," Dai said.

Of course, we haven't seen the planets directly, and are unlikely to in the lifetime of anyone alive today. But being able to detect them at all is an incredible testament to the power of microlensing, not to mention being evidence that there are planets in other galaxies.

Of course, common sense would dictate that planets are out there - but evidence is always nice.

"This is an example of how powerful the techniques of analysis of extragalactic microlensing can be," said Guerras.

"This galaxy is located 3.8 billion light years away, and there is not the slightest chance of observing these planets directly, not even with the best telescope one can imagine in a science fiction scenario.

"However, we are able to study them, unveil their presence and even have an idea of their masses. This is very cool science."

The research was published in The Astrophysical Journal.

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We Finally Know Why Galaxies Across The Universe Have All Those Weird Shapes

Prabhu TL September 16, 2017

This may change our understanding of cosmic evolution.

In 1926, famed astronomer Edwin Hubble developed his morphological classification scheme for galaxies. This method divided galaxies into three basic groups – elliptical, spiral and lenticular – based on their shapes. Since then, astronomers have devoted considerable time and effort in an attempt to determine how galaxies have evolved over the course of billions of years to become these shapes.

One of the most widely-accepted theories is that galaxies changed by merging, where smaller clouds of stars – bound by mutual gravity – came together, altering the size and shape of a galaxy over time. However, a new study by an international team of researchers has revealed that galaxies could actually assume their modern shapes through the formation of new stars within their centres.

The study, titled "Rotating Starburst Cores in Massive Galaxies at z = 2.5", was recently published in the Astrophysical Journal Letters.

Led by Ken-ichi Tadaki – a postdoctoral researcher with the Max Planck Institute for Extraterrestrial Physics and the National Astronomical Observatory of Japan (NAOJ) – the team conducted observations of distant galaxies in order to get a better understanding of galactic metamorphosis.

Evolution diagram of a galaxy. Credit: NAOJ

This involved using ground-based telescopes to study 25 galaxies that were at a distance of about 11 billion light-years from Earth. At this distance, the team was seeing what these galaxies looked like 11 billion years ago, or roughly 3 billion years after the Big Bang.

This early epoch coincides with a period of peak galaxy formation in the Universe, when the foundations of most galaxies were being formed. As Tadaki indicated in a NAOJ press release:

"Massive elliptical galaxies are believed to be formed from collisions of disk galaxies. But, it is uncertain whether all the elliptical galaxies have experienced galaxy collision. There may be an alternative path."

Capturing the faint light of these distant galaxies was no easy task and the team needed three ground-based telescopes to resolve them properly. They began by using the NAOJ's 8.2-m Subaru Telescope in Hawaii to pick out the 25 galaxies in this epoch.

Then they targeted them for observations with the NASA/ESA Hubble Space Telescope(HST) and the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile.

Whereas the HST captured light from stars to discern the shape of the galaxies (as they existed 11 billion years ago), the ALMA array observed submillimeter waves emitted by the cold clouds of dust and gas – where new stars are being formed.

By combining the two, they were able to complete a detailed picture of how these galaxies looked 11 billion years ago when their shapes were still evolving.

Observations of a galaxy 11 billion light-years away. Credit: ALMA, NASA/ESA Hubble, Tadaki et al.

What they found was rather telling. The HST images indicated that early galaxies were dominated by a disk component, as opposed to the central bulge feature we've come to associate with spiral and lenticular galaxies.

Meanwhile, the ALMA images showed that there were massive reservoirs of gas and dust near the centers of these galaxies, which coincided with a very high rate of star formation.

To rule out alternate possibility that this intense star formation was being caused by mergers, the team also used data from the European Southern Observatory's Very Large Telescope (VLT) – located at the Paranal Observatory in Chile – to confirm that there were no indications of massive galaxy collisions taking place at the time.

As Tadaki explained:

"Here, we obtained firm evidence that dense galactic cores can be formed without galaxy collisions. They can also be formed by intense star formation in the heart of the galaxy."

These findings could lead astronomers to rethink their current theories about galactic evolution and howthey came to adopt features like a central bulge and spiral arms. It could also lead to a rethink of our models regarding cosmic evolution, not to mention the history of own galaxy.

Who knows? It might even cause astronomers to rethink what might happen in a few billion years, when the Milky Way is set to collide with the Andromeda Galaxy.

As always, the further we probe into the Universe, the more it reveals. With every revelation that does not fit our expectations, our hypotheses are forced to undergo revision.

This article was originally published by Universe Today. Read the original article.

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This massive black hole just broke free, and is tearing through its own galaxy

Prabhu TL October 06, 2016

RIP everything in its path.

Supermassive black holes are thought to sit at the centre of every galaxy in the Universe. It’s not clear why they’re always in the middle, but we’re safe in the knowledge that those devastating whirlpools of nothingness stay where they’re supposed to... until they don’t.

A newly discovered black hole appears to have been knocked from its perch by another galaxy, and is now tearing - unanchored - through its own galaxy. Let’s all just take a moment to appreciate the very well-behaved black hole at the centre of the Milky Way, shall we?

Regular black holes form when a star at least five times more massive than the Sun runs out of fuel, and collapses in on itself to create a destructive void thatnot even light can escape.

There are also massive black holes - sometimes referred to as intermediate-mass black holes - which are 100 to 100,000 times more massive than our Sun.

Supermassive black holes, on the other hand, contain hundreds of millions of times the mass of our Sun. The biggest ones can even be as heavy as 10 billion Suns.

Massive and supermassive black holes are thought to be at the heart of every galaxy in the Universe.

This looming presence is intrinsic to the existence of a galaxy - they even grow in tandem with each other - but no one’s entirely sure why these black holes always end up at the centre.

One hypothesis is that the black hole existed first, and managed to pull an entire galaxy full of stuff in around it.

Another suggestion is that the dark matter halo that surrounds every galaxy concentrates new galaxy material in such a way that you end up with a massive or supermassive black hole in the centre, and stars everywhere else.

Regardless of how they got there, supermassive black holes tend to stay put in the centre of a galaxy - but physicists have hypothesised that on very rare occasions, something catastrophic can knock them free.

Now it looks like we’ve found one such 'wandering' supermassive black hole, tearing through the edges of galaxy SDSS J141711.07+522540.8, some 4.5 billion light-years from Earth.

We’ve known about this massive object, called XJ1417+52, for over a decade now, and previous estimates have placed its mass at around 100,000 times that of our Sun. But back when we first spotted it, it appeared to still be anchored to its galactic centre.

The team that spotted it, led by physicist Dacheng Lin from the University of New Hampshire, suggests that the black hole broke free when its galaxy merged or collided with a neighbouring galaxy - something that’s expected to happen to the Milky Way in 5 billion years or so.

It’s thought that when this collision happened, a sun from one galaxy wandered too close to the supermassive black hole of the other one, and the black hole got dislodged, and the sun shredded.

That explains why when the team observed the black hole for the first time between 2000 and 2002, it looked so incredibly bright. Only in the past few years did they manage to locate the source of this flash.

As George Dvorsky explains for Gizmodo, the gaseous debris produced by this encounter generated a tremendous amount of X-rays, that have since been picked up by NASA’s Chandra X-ray Observatory and the ESA’s XMM-Newton X-ray observatory.

To give you an idea of how bright the encounter was, it was 10 times brighterthan the brightest X-ray source ever seen for a potential wandering black hole, and it's also about 10 times further away from us than the previous record holder.

So... should we be worried about a rogue black hole that's doing what it wants, where it wants?

Well, unless we somehow figure out how to travel to places billions of light-years away, the answer is no. But spare a thought for whatever matter it runs into in its own galaxy, because death by black hole is no fun for anyone.

The discovery has been accepted for publication in the Astrophysical Journal, but you can read it at pre-print website, arXiv.org.

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Watch :This 8 minute Video To Know Everything About Universe(History) By- Neil DeGrasse Tyson

Prabhu TL August 01, 2015

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Expert mind-blower, Pluto-hater and all-around explainer Neil DeGrasse Tyson has now proved he can explain everything in the universe by explaining literally everything in the universe.

On MinutePhysics, the famed astrophysicist draws from his book “Origins: Fourteen Billion Years of Cosmic Evolution.” He starts with the beginning of time about 13.7 billion years ago, when “all the space, and all the matter, and all the energy of the known universe was contained in a volume less than one-trillionth the size of the point of a pin.” He ends with homosapiens, who are enabled “to deduce the origin and the evolution of the universe,” like Tyson just did.

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100+ Mind-Blowing Space Pictures by [NASA]

Prabhu TL September 02, 2014

Space is big, and if you have read>>[Einstein's Theory of Relativity] you know the concepts of space and time it’s also incredibly complex. As you scroll through these photos not only are you seeing some of our universe’s enormity, but you are also looking back in time thousands of years.
So allow yourself be humbled because here are the 100+ stack of incredible, mind-blowing pictures of stars,planets,galaxies,nebula's,...