Saturday November 18, 2017
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China Switches On World’s Largest Single-Dish Radio Telescope FAST

With a diameter of 500 meters (1,640 feet), the telescope, which cost nearly 1.2 billion yuan to build, dwarfs the 300 meter Arecibo Observatory in Puerto Rico

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Telescope. Wikimedia

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The world’s largest single-dish radio telescope — Five hundred meter Aperture Spherical Radio Telescope (FAST) — has received its first signals from space. The behemoth, nestled in a natural crater in Guizhou Province in southwest China, will now be tested for three years before it becomes fully operational. “This is very exciting,” Peng Bo, FAST deputy….repubhubembed{display:none;}


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Astronomers Discover the ‘Biggest Stellar Puzzle’, Bizarre Star that Refuses to Die

The study calculated that the star that exploded was at least 50 times more massive than the Sun and probably much larger.

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This star shines brighter every time it explodes. Read to know more! (representative image) Wikimedia

New York, November 9, 2017 : An international team of astronomers has made a bizarre discovery – a star that refuses to stop shining despite exploding more than once over a period of 50 years.

The explosions of stars, known as supernovae, have been observed in the thousands and in all cases they marked the death of a star.

But a new study, published in the journal Nature, challenges known theories about the death of stars. Their observations included data from Keck Observatory on Maunakea in Hawaii.

“The spectra we obtained at Keck Observatory showed that this supernova looked like nothing we had ever seen before. This, after discovering nearly 5,000 supernovae in the last two decades,” said study co-author Peter Nugent from Lawrence Berkeley National Laboratory in the US.

ALSO READ Giant planet orbiting a small star find stuns scientists: NGTS Survey

“While the spectra bear a resemblance to normal hydrogen-rich core-collapse supernova explosions, they grew brighter and dimmer at least five times more slowly, stretching an event which normally lasts 100 days to over two years,” Nugent said.

The supernova, named iPTF14hls, was discovered in September 2014 by the Palomar Transient Factory. At the time, it looked like an ordinary supernova.

Several months later, astronomers at Las Cumbres Observatory in the US noticed the supernova was growing brighter again after it had faded.

When astronomers went back and looked at archival data, they were astonished to find evidence of an explosion in 1954 at the same location.

This star somehow survived that explosion and exploded again in 2014.

“This supernova breaks everything we thought we knew about how they work. It’s the biggest puzzle I’ve encountered in almost a decade of studying stellar explosions,” said lead author Iair Arcavi, a NASA Einstein postdoctoral fellow at LCO and the University of California Santa Barbara.

The study calculated that the star that exploded was at least 50 times more massive than the Sun and probably much larger.

Supernova iPTF14hls may have been the most massive stellar explosion ever seen. The size of this explosion could be the reason that conventional understanding of the death of stars failed to explain this event.

Astronomers continue to monitor the supernova, which remains bright three years after it was discovered. (IANS)

 

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Astronomers Discover New ‘Mid-size’ Black Hole 100,000 Times More Massive than the Sun

Scientists predict that nearly 100 million of these small black holes should exist in the Milky Way, however only about 60 have been found till now

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Black hole in milky way
A near-infrared image of a black hole at the center of the Milky Way galaxy as seen with Hubble Space Telescope/NICMOS. (NASA/STScI) (VOA)
  • Researches in Japan have discovered a super-massive black hole in Milky Way Galaxy
  • The black hole is believed to weigh as much as 400 suns
  • According to studies,  at least 100 million of these small black holes should exist in the Milky Way

Japan, September 5, 2017 : Astronomers have found new evidence for the existence of a mid-sized black hole, considered the missing link in the evolution of super-massive black holes.

Astronomers in Japan found the possible black hole in our own Milky Way galaxy, a long-theorized object which is bigger than the small black holes formed from a single star, but still much smaller than giant black holes such as the one at the center of the Milky Way.

Black holes are difficult to find because they do not emit any light. However, scientists can detect them by their influence on nearby objects.

The astronomers in Japan found new evidence of the so-called intermediate-mass black hole when they turned a powerful telescope in Chile’s Atacama desert on a gas cloud near the center of the Milky Way. The gases in the cloud move at unusual speeds, and the scientists believed they were being pulled by immense gravitational forces. They say the gravitational force is likely caused by a black hole measuring about 1.4 trillion kilometers across.

black hole in Milky way galaxy
Radio telescope antennas of the ALMA (Atacama Large Millimeter/submillimeter Array) project are seen in the Atacama desert, some 1500 km north of Santiago, Chile, VOA

The findings are published in the journal Nature Astronomy.

Theoretical studies predict at least 100 million of these small black holes should exist in the Milky Way, however only about 60 have been found.

The possible mid-sized black hole is much smaller than the super massive black hole that is located in the center of the galaxy, known as Sagittarius A, which weighs as much as 400 million suns.

“This is the first detection of an intermediate-mass black hole candidate in the Milky Way galaxy,” said the study’s leader, Tomoharu Oka from Keio University, Japan.

If confirmed, the intermediate-mass black hole could help explain how supermassive black holes operate. One theory is that supermassive black holes, which are at the center of most massive galaxies, are formed when smaller black holes steadily coalesce into larger ones. However, until now no definitive evidence has existed for intermediate-mass black holes that could indicate a middle step between the small and massive black holes already detected.

Researchers say they will continue to study the intermediate-mass black hole candidate in the hope of confirming its existence. (VOA)

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The Oldest Known Asteroid Family has finally been identified by Astronomers

Identifying the very oldest asteroid families, those billions of years old, is challenging, because over time, a family spreads out

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Oldest known asteroid family
An asteroid family. Wikimedia

August 08, 2017: Astronomers have identified the oldest known asteroid family, which extends throughout the inner region of the main asteroid belt.

The team also discovered a relatively sparse region of the main asteroid belt, where the few asteroids present are likely pristine relics from early in solar system history.

“The family we identified has no name, because it is not clear which asteroid is the parent,” said Kevin Walsh, astronomer at Southwest Research Institute in the US and co-author of a study published online in the journal Science.

Also Read: Astronomers Detect Strange ‘Radio Signals’ Coming From Dwarf Star 11 Light Years Away

“This family is so old that it appears to have formed over four billion years ago, before the gas giants in the outer solar system moved into their current orbits. The giant planet migration shook up the asteroid belt, removing many bodies, possibly including the parent of this family,” Walsh said.

Finding and studying asteroid families allows scientists to better understand the history of main belt asteroids.

But identifying the very oldest asteroid families, those billions of years old, is challenging, because over time, a family spreads out.

As asteroids rotate in orbit around the Sun, their surfaces heat up during the day and cool down at night.

This creates radiation that can act as a sort of mini-thruster, causing asteroids to drift widely over time.

After billions of years, family members would be almost impossible to identify, until now.

The team used a novel technique, searching asteroid data from the inner region of the belt for old, dispersed families.

They looked for the “edges” of families, those fragments that have drifted the furthest.

“Each family member drifts away from the centre of the family in a way that depends on its size, with small guys drifting faster and further than the larger guys,” said team leader Marco Delbo, an astronomer from the Observatory of Cote d’Azur in Nice, France.

“If you look for correlations of size and distance, you can see the shapes of old families,” Delbo noted.

“By identifying all the families in the main belt, we can figure out which asteroids have been formed by collisions and which might be some of the original members of the asteroid belt,” Walsh said.

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“We identified all known families and their members and discovered a gigantic void in the main belt, populated by only a handful of asteroids. These relics must be part of the original asteroid belt. That is the real prize, to know what the main belt looked like just after it formed,” Walsh noted.

The team plans to apply this new technique to the entire asteroid belt to reveal more about the history of the solar system by identifying the primordial asteroids versus fragments of collisions. (IANS)