What Happens When A Star Hits A Supermassive Black Hole?

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Supermassive black holes, with masses ranging from millions to billions of times the mass of our Sun, have such a huge gravity that once matter or energy gets close enough, it can not escape their grip and get pulled in. 

According to Einstein's general theory of relativity and also, most astronomers believe that black holes are cosmic singularities with no physical surface area, surrounded by an invisible gravitational barrier known as the event horizon.

While the supermassive black holes are thought to exist at the heart of almost all galaxies, including our own, there is another opinion based on modified theories of general relativity, suggest that instead of a black hole there is a central massive object that has somehow managed to avoid gravitational collapse to a singularity and have hard surface area.

When a star hits a black hole.
So, what happens when a star falls into a supermassive black hole? Does it swallowed entirely by the black hole or crash into the hard surface of a massive object and get destroyed. 

Pawan Kumar an astrophysicist from the University of Texas at Austin along with his team, come up with a test to determine which theory is correct. "Our whole point here is to turn this idea of an event horizon into an experimental science, and find out if event horizons really do exist or not," said Pawan Kumar.

The researchers tried to figure out what would be the scenario if a star hit the hard surface of a supermassive object at the center of a galaxy, the star’s gas would envelope the object, shining visibly for months or perhaps even years. Once they knew what to search for, the team calculated how often this should be seen in the nearby galaxies.

Then they searched a recent archive of telescope observations made by Pan-STARRS telescope in Hawaii. During a period of 3.5 years, the telescope scanned half of the northern hemisphere sky, looking for 'transients', things that glow for a while and then fade. 

Their aim was to find transients with the expected light signature of a star falling toward a supermassive object and hitting a hard surface. "Given the rate of stars falling onto black holes and the number density of black holes in the nearby universe, we calculated how many such transients Pan-STARRS should have detected over a period of operation of 3.5 years. It turns out it should have detected more than 10 of them if the hard-surface theory is true," explains one of the team, Wenbin Lu.

So, did they find any?
No, they did not find any transients with that expected light signature of a star hitting a supermassive object. It means that when a star falls into a supermassive black hole, it just simply pass the event horizon and vanishes completely.

"Our work implies that some, and perhaps all, black holes have event horizons and that material really does disappear from the observable universe when pulled into these exotic objects, as we've expected for decades. General Relativity has passed another critical test," says one of the researchers, Ramesh Narayan from the Harvard-Smithsonian Center for Astrophysics.

The researchers are now proposing to improve the test with a larger telescope, the Large Synoptic Survey Telescope, presently under construction in Chile. LSST will perform surveys like the Pan-STARRS telescope, but with much greater sensitivity.


article reference:- news.utexas.edu
image credit:- nasa/jpl caltech

When Science meets Nature, this happens.

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When science meets with nature, it always creates something special and this time it's crated a rainbow.

The beautiful phenomenon happened during the recent RS-25 engine test conducted by NASA to collect performance data of the rocket engine which will help power the new Space Launch System rocket to launch astronauts aboard the Orion spacecraft, deeper into space than ever before.

Shown mostly from the viewpoint of an drone, NASA also released a video of the test on it's youtube channel.



article reference:- youtube.com/NASA.gov Video
credit:- NASA

Charged Particles from Outer Space are causing Disturbance on Earth’s Electronic Devices.

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We may not realise it, but when cosmic rays travels through the Earth's atmosphere at a speed of light, they create millions of electrically charged particles that strike our body in every second. 

While harmless to living organisms, a small part of these particles carry enough energy to interfere with the operation of the microelectronic circuitry in our electronic devices and can alter individual bits of data stored in a memory. 

This is called a single event upset or SEU and the outcome of this event could be various, from freezing your smartphone's UI to bringing down a passenger jet plane.

"This is a really big problem, but it is mostly invisible to the public," said Bharat Bhuva, professor of electrical engineering at Vanderbilt University during the annual meeting of the American Association for the Advancement of Science. Bhuva is a member of Vanderbilt’s Radiation Effects Research Group, established in 1987 to study the effects of radiation on electronic systems.

Serious incidents happened due to SEUs
As pointed out by Bhuva, there have been a number of incidents that illustrate how serious this problem can be. For example, in 2003 a bit flip in an electronic voting machine in Belgium, added 4,096 extra votes to one candidate. The error was only detected because it gave the candidate more votes than were possible. 

In 2008, the avionics system of a Qantus passenger jet flying from Singapore to Perth suffered from a SEU that caused the autopilot to disengage. As a result, the aircraft dove 690 feet in only 23 seconds, injuring the passengers seriously enough to divert the aircraft to the nearest airstrip. 

There have been also a number of unexplained glitches in airline computers, some of which experts feel must have been caused by SEUs. In addition to that SEUs can also disturb the performance of consumer electronics like computers, smartphones etc.

So, what's the solution? 
Since it is difficult to know when and where these particles will strike, the malfunctions they cause are very difficult to characterise. As a result, determining the prevalence of SEUs is not easy or straightforward.

"When you have a single bit flip, it could have any number of causes. It could be a software bug or a hardware flaw, for example. The only way you can determine that it is a single-event upset is by eliminating all the other possible causes," professor Bhuva explained. 

However, there are ways to design computer chips to dramatically reduce their vulnerability. For example, manufactures can design the processors in triplicate formation, as the probability of a SEUs will occur in two of the circuits at the same time is vanishingly small. 

So if two circuits produce the same result it should be correct. That's the same trick NASA use in it's spacecraft computer systems to maximise it's reliability in space. The good news is that the semiconductor manufacturers are all very concerned about this problem and taking steps to solve it.


article reference:- Research News @Vanderbilt 
image source:- pixabay

The Flame Nebula NGC 2024.

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The Flame Nebula, known as NGC 2024 is an emission nebula lies 1500 light years from Earth in the constellation Orion. Although, it appears like a billowing fire but fire, the rapid acquisition of oxygen, is not what makes this Flame glow. 

Rather the bright star Alnitak, the easternmost star in the Belt of Orion, shines energetic ultraviolet light into the Flame that knocks electrons away from the clouds of hydrogen gas that reside there. Much of the glow results when the electrons and ionized hydrogen recombine. 

Additional dark gas and dust lies in front of the bright part of the nebula and this is what causes the dark network that appears in the center of the glowing gas. The Flame Nebula is part of the Orion Molecular Cloud Complex, a star-forming region that includes the famous Horsehead Nebula.

According to a new study, the stars at the center of NGC 2024 were about 200,000 years old while those on the outskirts were about 1.5 million years in age.

Image Credit: ESO/J. Emerson/VISTA. Acknowledgment: Cambridge Astronomical Survey Unit

Our Home Planet and it's Moon, as Seen Form Mars.

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From one of the most powerful spacecraft orbiting Mars, comes a new composite image taken by the Mars Reconnaissance Orbiter [MRO] shows how our home planet Earth and its Moon appear together when seen from the red planet.

Taken on November 20, 2016 by the High Resolution Imaging Science Experiment [HiRISE] camera on NASA's MRO, the photograph is constructed from the best image of Earth and the best image of the moon from four sets of images, which were acquired to calibrate HiRISE data. When the component images were taken, Mars was about 205 million kilometers [127 million miles] away from Earth.

In this image, the reddish feature near the middle of the face of Earth is Australia. Southeast Asia appears as the reddish area near the top, Antarctica is the bright blob at bottom-left. Other bright areas are clouds.

As NASA describes in it's Official website, the image combines two separate exposures. For presentation, the exposures were processed separately to optimize detail visible on both Earth and the moon. The moon is much darker than Earth and would barely be visible if shown at the same brightness scale as Earth. But the combined view retains the correct positions and sizes of the two bodies relative to each other. 

You may have noticed that, in the photograph both Earth and moon appear closer than they actually are because, the observation was planned for a time at which the moon was almost directly behind Earth, from Mars' point of view, to see the Earth-facing side of the moon. 

With HiRISE and five other instruments, the MRO has been investigating Mars since 2006. In 2007 HiRISE had also snapped a similar image, when Earth was 142 million kilometers [88 million miles] from Mars.
In this image, the west coast outline of South America could be seen at the lower right, but clouds are the dominant features.



article reference:- nasa.gov & jpl.nasa.gov
image credit:- nasa/jpl-caltech/univ. of arizona 

A Halloween Treat from Space, a Solar Jack-o-Lantern captured by SDO.

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An amazing image captured by NASA's Solar Dynamics Observatory [SDO] shows that even the Sun is getting into the Halloween spirit.

SDO snapped this photo on October 8th, 2014. In this image, solar flares have gathered to form what appears to be a spooky face on sun's surface. The active regions on sun appear brighter because those are the areas that emit more light and energy - markers of an intense and complex set of magnetic fields hovering in the sun’s atmosphere, the corona. 

This composite image blends two sets of extreme ultraviolet wavelengths at 171 and 193 angstroms, giving the sun that perfect Halloween-like appearance.



article reference:- nasa.gov
image credit: nasa/sdo

 
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