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When a star 20 times larger than our Sun dies, it can explode into a supernova and squeeze back into a dense black hole (with the help of gravity). But that explosion is never perfectly symmetrical, so sometimes, the resulting black holes fly into space. These wandering objects are often called “renegade black holes” because they float freely around, unattached to other celestial bodies.

But that name could be a “wrong name,” according to Jessica Lou, an associate professor of astronomy at the University of California, Berkeley. She prefers the term “free-floating” to describe these black holes. “Outlaw,” she says, implies that nomads are rare or unusual – or not good.

That is certainly not the case. Astronomers estimate that there are as many as 100 million such black holes roaming our galaxy. But since they are lonely, they are extremely difficult to find. Until recently, these so-called black holes were known only through theory and calculations.

“They’re ghosts, so to speak,” says Lou, tasked with finding the free-floating black holes of the Milky Way.

[Related: We’re still in the dark about the key black hole paradox]

Earlier this year, two teams of space explorers separately discovered discoveries of what could only be one of these wandering black holes. One of those teams was led by Casey Lam, a graduate student at Lua’s lab. The second was led by Kailash C. Sahu, an astronomer from the Space Telescope Science Institute. Both teams published their papers in a free open access journal without peer review.

Scientists will receive more data from the Hubble Space Telescope in October, which Lou says should help “solve the mystery of whether this is a black hole or a neutron star.” “There’s still a lot of uncertainty about how the stars die and the remnants of the ghosts they leave behind,” she notes. When stars much more massive than our Sun run out of nuclear fuel, they are thought to collapse into either a black hole or a neutron star. “But we don’t know exactly which ones die and turn into neutron stars or die and turn into black holes,” Lou adds. “We don’t know when a black hole is born and a star dies, is there a violent supernova explosion? Or does it fall directly into a black hole and maybe just burp a little? ”

With the stellar things that make up everything we know in the world, understanding the afterlife of the stars is the key to understanding how we came to be.

How to spot a black hole on the loose

Black holes are inherently invisible. They capture all the light they come across, so that the human eye has nothing to perceive. Therefore, astronomers must be creative to detect these dense, dark objects.

They usually look for anomalies in gas, dust, stars and other material that could be caused by the very strong gravity of the black hole. If a black hole separates material from another celestial body, the resulting disk of debris surrounding the black hole may be clearly visible. On the same subject : Boris Johnson Gives Politics a Botox Jab: The Reading with Allegra Stratton. (So ​​astronomers took the first direct image of one in 2019 and a picture of a black hole in the center of the Milky Way earlier this year.)

But if the black hole does not cause chaos by its gravitational force, there is hardly anything that could be detected. This is often the case with these movable black holes. So astronomers like Lu use another technique called astrometric or gravitational microlensing.

“What we’re doing is waiting for a random alignment of one of these free-floating black holes and a background star,” Lou explains. “When the two of them align, the light from the background star is distorted by the gravity of the black hole [in front of it]. It appears as the brightness of a star [in astronomical data]. It also seems to take a little walk in the sky, a little sway, so to speak. ”

The background star doesn’t actually move – it seems to move off its course when a black hole or other compact object passes in front of it. This is because the gravity of a black hole distorts the space-time tissue, according to Albert Einstein’s General Theory of Relativity, which changes the light of stars.

The chances that a wandering black hole could pass through our celestial neighborhood and disrupt life on Earth are “astronomically small”.

Astronomers use microlensing to study all sorts of temporary phenomena in space, from supernovae to exoplanets orbiting their stars. But it is difficult to do that with terrestrial telescopes, because the Earth’s atmosphere can blur images.

“In astrometry, you try to measure the position of something very precisely, and you need very sharp images,” Lou explains. So astronomers rely on space telescopes, such as Hubble, and several terrestrial instruments that have sophisticated systems to adapt to atmospheric disturbances. “There are only three objects in the world that can perform this astrometric measurement,” Lu says. “We’re working at the pinnacle of what our technology can do today.”

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The first rogue black hole? 

It was the illumination, or “gravity lens event” as Lou calls it, and her and Sahu’s team spotted it in data from the 2011 Hubble Space Telescope. See the article : Business Beginnings: A new salad and a new patio in downtown Evanston. Something, they assumed, must be passing in front of that star.

To find out what caused the oscillation and the change in intensity in the star’s light, two measurements are needed: brightness and position. Astronomers observe that same point in the sky over time to see how light changes as an object passes in front of a star. This gives them the data they need to calculate the mass of that object, which in turn determines whether it is a black hole or a neutron star.

“We know that the thing that works with the lens is difficult. We know it’s heavier than your typical star. And we know it’s dark, “said Lou. “But we’re still a little uncertain how accurate it is and how accurate.” If it’s just a little heavy, say, one and a half times the mass of our Sun, it could actually be a neutron star. But if it is three to 10 times more massive than our Sun, then it would be a black hole, Lou explains.

As the two teams collected data from 2011 to 2017, their analyzes revealed markedly different masses of that compact object. Sahu’s team determined that the wandering object has a mass seven times larger than our Sun, which would place it in the territory of a black hole. But Lam and Lu’s team calculated that it was less massive, somewhere between 1.6 and 4.4 solar masses, which includes both possibilities.

[Related: Black holes can swallow neutron stars whole]

Astronomers cannot be sure which calculation is accurate until they get a chance to find out how bright the background star is normally and its position in the sky when something does not pass in front of it. They were not focused on that star before they noticed its unusual brightness and oscillation, so only now do they have the opportunity to make those basic observations because the effect of the lens has faded, Lou explains. Those observations will come from new Hubble data in the fall.

What they do know is that the object in question is located in the spiral arm of the Milky Way galaxy and is currently about 5,000 light-years from Earth. This detection also suggests that the nearest wandering black hole could be less than 100 light-years away, Lou says. But that is not a cause for concern.

“Black holes are a drain. If you get close enough, they will eat you, ”said Lu. “But you have to get closer, much closer than we think we usually imagine.” The boundary around a black hole that marks the line at which light can still escape its gravity, called the event horizon, usually has a radius below 20 miles.

The chances that a wandering black hole could pass through our celestial neighborhood and disrupt life on Earth are “astronomically small,” Lu says. “It’s the size of the city. So, a black hole could pass by the solar system, and we can hardly notice it. “

But she doesn’t rule it out. “I’m a scientist,” she says. “I can’t say there’s no way.”

Whether the first teams discovered a wandering black hole or a neutron star, Lu says, “the real revolution these two works show is that we can now find these black holes using a combination of brightness and position measurements.” This opens the door to the discoveries of more light-capturing nomads, especially as new telescopes appear online, including the Vera C. Rubin Observatory currently under construction in Chile and the Roman Nancy Grace Space Telescope to be launched later this decade.

As Lu sees it, “the next chapter in the study of black holes in our galaxy has already begun.”

Will the Sun become a black hole? No, it’s too small for that! The sun should be about 20 times bigger to end its life like a black hole.

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Is there a white hole?

White holes cannot exist because they violate another law of thermodynamics. General relativity is time symmetric. This may interest you : After a year of historic political gains, black women continue to push toward governors. He does not know about the other law of thermodynamics, and he does not know in which direction cause and effect go.

Is there a white hole in space? Are there white holes? There is currently no evidence to suggest the existence of white holes in space. For now, the white hole is a purely theoretical concept. The closest thing we’ve seen to potentially seeing a white hole in space comes from an article published in 2011.

How white hole is formed?

In a 2014 study, Rovelli and his team suggested that when a black hole evaporates to the point where it can no longer shrink because space-time cannot be compressed into anything less, the dying black hole will then return and form a white hole.

What happens if you go into a white hole?

White holes are theoretical cosmic regions that function opposite to black holes. Just as nothing can escape a black hole, nothing can enter a white hole. White holes have long been thought to be the fruit of a general theory of relativity derived from the same equations as their collapsed star brothers, black holes.

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Can you be alive inside a black hole?

Basically, it might be theoretically possible (but probably not very likely) to survive a journey into a massive black hole, and some scientists predict that some forms of extraterrestrial life might even live within the Cauchy horizon. However, you should say goodbye to everyone you know and love, because this move is permanent.

What happens if a man is in a black hole? The event horizon of a black hole is a point of no return. Anything that crosses this point will be swallowed by a black hole and will disappear forever from our known universe. The distance from the center of mass of a black hole to the place where gravity is too strong to be overcome is called the event horizon.

Can you survive inside a black hole?

Thus a person would pass through the horizon of the event intact, would not be stretched into a long, thin noodle, survive and float painlessly past the horizon of a black hole. A person who falls into a supermassive black hole would probably survive.

Can a person go into a black hole?

It is absolutely impossible to get into a black hole and get out again. In a way this is the true definition of a black hole. Not even light can escape, and light moves very fast!

Could a human survive a black hole?

Thus a person would pass through the horizon of the event intact, would not be stretched into a long, thin noodle, survive and float painlessly past the horizon of a black hole. A person who falls into a supermassive black hole would probably survive.

Is there a black hole in our galaxy? In 2019, the Event Horizon Telescope team released the first image of a black hole in the center of the M87 galaxy. The black hole in the center of this galaxy, called M87, is 2,000 times larger than Sagittarius A and 7 billion times larger than the mass of the Sun.

Are you still alive in a black hole?

Nothing can escape a black hole. Any trip to the black hole would be one-way. Gravity is too strong and you can’t go back to space and time to get home. In addition, your body would be stretched and destroyed by the distortion of space and the amount of radiation surrounding the event horizon.

What is a black hole made of?

Most black holes are formed from the remains of a large star that dies in a supernova explosion. (Smaller stars become dense neutron stars, which are not massive enough to capture light.)

What happens if humans enter a black hole?

If you heroically jumped into a black hole of stellar mass, your body would be subjected to a process called ‘spagetification’ (no, really, it is). The gravitational force of a black hole would compress you from top to toe, while at the same time stretching you … so, spaghetti.

Can you shoot down a nuke?

The SM-3 Block II-A missile equipped with the Aegis ballistic missile defense showed that it could shoot down the ICBM target on November 16, 2020.

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