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'Black neutron star' discovery baffles astronomers – BBC News



Scientists have discovered an astronomical object that has never been observed before.

It is more massive than collapsed stars, known as “neutron stars”, but has less mass than black holes.

Such “black neutron stars” were not thought possible and will mean ideas for how neutron stars and black holes form will need to be rethought.

The discovery was made by an international team using gravitational wave detectors in the US and Italy.

Charlie Hoy, a PhD student from Cardiff University, UK, involved in the study, said the new discovery would transform our understanding.

“We can’t rule out any possibilities,” he told BBC News. “We don’t know what it is and this is why it is so exciting because it really does change our field.”

Mr Hoy is part of an international team working for the Ligo-Virgo Scientific Collaboration.

The international group, which has strong UK involvement backed by the Science and Technologies Facilities Council, has laser detectors several kilometres long that are able to detect minute ripples in space-time caused by the collision of massive objects in the Universe.

The collected data can be used to determine the mass of those objects involved.

Last August, the instruments detected the collision of a black hole 23 times the mass of our Sun with an object of 2.6 solar masses.

That makes the lighter object more massive than the heaviest type of dead star, or neutron star, previously observed – of just over two solar masses. But it was also lighter than the lightest black hole previously observed – of around five solar masses.

Astronomers have been searching for such objects in what they’ve come to call the “mass gap”.

Writing in the journal The Astrophysical Journal Letters, the research team believes that of all the possibilities, the object is most likely to be a light black hole, but they are not ruling out any other possibilities.

  • Gravitational waves are a prediction of the Theory of General Relativity
  • It took decades to develop the technology to directly detect them
  • They are ripples in the fabric of space-time generated by violent events
  • Accelerating masses will produce waves that propagate at the speed of light
  • Detectable sources include merging black holes and neutron stars
  • Ligo/Virgo fire lasers into long, L-shaped tunnels; the waves disturb the light
  • Detecting the waves opens up the Universe to completely new investigations

Having collided with the large black hole, the object no longer exists. However, there should be further opportunities to learn more about these mass-gap objects from future collisions, according to Prof Stephen Fairhurst, also at Cardiff.

“It is a challenge for us to determine what this is,” he told BBC News. “Is this the lightest black hole ever, or is it the heaviest neutron star ever?”

If it is a light black hole then there is no established theory for how such an object could develop. But Prof Fairhurst’s colleague, Prof Fabio Antonioni, has proposed that a solar system with three stars could lead to the formation of light black holes. His ideas are receiving increased attention following the new discovery.

If, however, this new class of object is a heavy neutron star then theories for how they form may also need to be revised, according to Prof Bernard Schutz of the Max Planck Institute for Gravitational Physics in Potsdam, Germany.

“We don’t know a lot about the nuclear physics of neutron stars. So, people who are looking at exotic equations that explain what goes on inside them might be thinking, ‘maybe this is evidence that we can get much heavier neutron stars’.”

Both black holes and neutron stars are thought to form when stars run out of fuel and die. If it is a very large star, it collapses to form a black hole, an object with such strong gravitational force that not even light can escape its grasp.

If the starting star is below a certain mass, one option is for it to collapse into a dense ball composed entirely of particles called neutrons, which are found inside the heart of atoms.

The material from which neutron stars are composed is so tightly packed that one teaspoonful would weigh 10 million tonnes.

A neutron star also has powerful gravity pulling it together, but a force between the neutrons, called the nuclear strong force, pushes the particles apart, counteracting the gravitational force.

Current theories suggest that the gravitational force would overcome the nuclear force if the neutron star were much larger than two solar masses – and cause it to collapse into a black hole.

According to Prof Nils Andersson of Southampton University, if the mystery object is a heavy neutron star then the theorists will have to rethink what goes on in these objects.

“Nuclear physics is not a precise science where we know everything,” he said.

“We don’t know how the nuclear strong force operates under the extreme conditions you need inside a neutron star. So, every single current theory we currently have of what goes on inside of one has some uncertainty.”

Prof Sheila Rowan, director of the University of Glasgow’s Institute for Gravitational Research (IGR), said the discovery challenges current theoretical models.

“More cosmic observations and research will need to be undertaken to establish whether this new object is indeed something that has never been observed before or whether it may instead be the lightest black hole ever detected.”

  • A laser is fed into the machine and its beam is split along two paths
  • The separate paths bounce back and forth between damped mirrors
  • Eventually, the two light parts are recombined and sent to a detector
  • Gravitational waves passing through the lab should disturb the set-up
  • Theory holds they should very subtly stretch and squeeze its space
  • This ought to show itself as a change in the lengths of the light arms
  • The photodetector captures this signal in the recombined beam

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Here's how to view Comet NEOWISE as it races towards Earth – CTV News



Early risers in the northern hemisphere will be treated to a view of a recently identified comet, which has suddenly become visible to the unaided eye, as it hurdles towards Earth.

Comet NEOWISE – technically called C/2020 F3 (NEOWISE) – was first discovered on March 27 by the Near Earth Object Wide-field Infrared Survey Explorer (NEOWISE) space telescope launched by NASA in 2009.

At the time, astronomers were unsure if the comet would meet a similar fate to other comets before it, such as Comet ATLAS and Comet SWAN, and break apart as it travelled close to the sun and warmed up.

However, it appears Comet NEOWISE survived its closest approach to the sun late last week and is now making its way closer to Earth before it is expected to return to the outer solar system, according to NASA.

The space agency said the comet has become one of the few “naked-eye comets” of the 21st century after it “suddenly” became visible to the unaided eye this week.

“Word spread quickly, and the comet has already been photographed behind many famous sites and cities around the globe,” NASA said in the caption of a photo of Comet NEOWISE passing over Lebanon on Sunday, which they shared as their “Astronomy Photo of the Day” on Tuesday.  

Although the future brightness of the comet “remains somewhat uncertain” because there’s still a chance it may break apart and therefore dim, NASA said the comet is likely to continue to be visible in the early morning sky this week and in the early evening sky next week.

According to NASA solar system ambassador Eddie Irizarry, Comet NEOWISE is visible at dawn now, but it will be at its highest in the dawn sky around July 11. The comet may be a little tricky to catch, he said, because it will be set against the brightening sky in the northeastern horizon, as opposed to a dark night sky.

However, Comet NEOWISE may become easier to spot later in the month after it gradually dips below the horizon and reappears in the early evening sky around July 12 to 15. When that occurs, it will then be visible at dusk (just after sunset) in the low northwest horizon, Irizarry said.

“If the comet remains relatively bright, it might be easier to see in the second half of July during evening dusk, because, at that time, it will appear somewhat higher in the sky,” he said.

Although it may be difficult for the average stargazer to spot the comet in the early mornings right now, some skilled photographers have already managed to capture the speeding comet and its streaking tail.

Even though some people have been able to spot the Comet NEOWISE without any instruments, Irizarry said most skywatchers would benefit from the use of binoculars or even a good camera.

Irizarry has also published several illustrations detailing the comet’s location in relation to different constellations so interested viewers know where in the sky to look.

On the chance the comet fades later in the month, Irizarry said it’s still a worthwhile endeavor for people to wake up early to try to catch it while it’s in the morning skies.

“It’s still a good idea to get up early in the morning this week and try for a glimpse of comet NEOWISE while it’s still relatively bright, just in case it gets fainter later in the month,” he explained.

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Health authority warns of possible COVID-19 exposure at Vancouver bar and nightclub – Yahoo News Canada



Vancouver Coastal Health is asking anyone who visited the bar and nightclub areas of the Hotel Belmont in downtown Vancouver on June 27 and 29 to monitor themselves for symptoms of COVID-19. 

Someone who tested positive for coronavirus was in those parts of the hotel on those days, the health authority said in a statement Monday.

There is no risk to anyone who visited the hotel outside those dates, the statement added. 

Jasmine Mooney, director of marketing and partner at Hotel Belmont, said protocols are being followed.

“We are working diligently alongside, and following all recommendations from Vancouver Coastal Health, Work Safe BC and The Provincial Health Officer,” she said. 

People who may have been exposed are being told to monitor themselves for 14 days and continue their daily activities.

If they develop symptoms of COVID-19, Vancouver Costal Health is asking that they get tested and immediately self-isolate.

Symptoms of COVID-19 may include fatigue, loss of appetite, fever, cough, sore throat, fatigue, runny nose, sore throat loss of smell or diarrhea.

The virus is spread by respiratory droplets when an infected person coughs or sneezes.

It can also spread when a healthy person touches an object or surface with the virus on it and then touches their mouth, nose or eyes before washing their hands.

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COVID-19: Vancouver bar patrons may have been exposed to virus – Cape Breton Post



Vancouver Coastal Health is alerting bar patrons who were at Vancouver’s Hotel Belmont a week ago that they may have been exposed to the novel coronavirus.

The VCH says individuals who tested positive for COVID-19 attended the hotel’s bar and nightclub on both June 27 and 29.

Bar-goers who patronized the Hotel Belmont, located at the corner of Nelson and Granville streets, on either of those nights are advised to monitor themselves for 14 days.

“As long as they remain healthy and do not develop symptoms, there is no need to self-isolate and they should continue with their usual daily activities. If you have no symptoms, testing is not recommended because it is not accurate or useful,” the VCH said in a statement.

“If you develop any of these symptoms of COVID-19, please seek COVID-19 testing and immediately self-isolate. Please call ahead and wear a mask when seeking testing.”

The VCH said there is no known risk to anyone who attended the Hotel Belmont outside these two dates.

Copyright Postmedia Network Inc., 2020

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