Questions tagged [black-hole]

Questions regarding points of extremely high mass density, which creates an extremely strong gravitational field from which light cannot escape.

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What is the Schwarzschild radius actually?

I am currently writing a detailed essay about black holes, the history of their discovery and their characteristics and I can't find the appropriate literature online and in my local libraries (I even ...
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(NASA's ANITA Results) Can White Hole's Collide? Can 2 White Holes Gravitationally Interact, like Black Holes? [closed]

Edit: I'm referring to NASA's ANITA test results of Tau Neutrino's coming 'Up' from Earth as supporting evidence to White Holes existence. If the schwarzschild radius for a black hole & white ...
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Could the unseen companion of HR 6819 be a close binary system?

Recently there was an announcement of a black hole candidate in the HR 6819 system (ESO Instrument Finds Closest Black Hole to Earth). In the proposed system, the black hole forms a close binary ...
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Is it possible that some of the confirmed exoplanets are in fact primordial black holes?

Recently astronomers discovered a black hole lying just 1000 light-years from Earth, in a triple star system (HR 6819) that can be seen with the naked eye. This discovery has increased the possibility ...
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any proof that stars are born, and die?

I've heard from a lot of people that stars are "born" (usually from black holes), then grow bigger, then eventually "die" by some kind of supernova etc., but have any of these events actually been ...
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Radial velocity data in ALADIN or TOPCAT for Binary Systems

I just installed both, Aladin and Topcat VO tools. I want to know how to search for: HD 226868 and A0620-00 radial velocity data or photometric curves to derive the hidden black hole mass in those ...
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Objects falling in a black hole radiate their mass?

An object reaching the event horizon has almost infinite kinetic energy. When the total energy of the object surpasses the breaking energy of the electroweak field , the Higgs mechanism would stop ...
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Is the object a pulsar

We have a star having 1.8 solar mass. Justify any four means (measurable/ observed properties) by which you can identify that the object is a Pulsar and not a white dwarf or a Black Hole. So one ...
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A question regarding the evolution of black holes [duplicate]

If to an outside observer, matter takes infinite time to get to the horizon, does that mean that to any outside observer the size of the black hole never increases?
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Is it possible that it actually takes an infinite amount of time to reach the apparent horizon of a black hole?

I know a black hole can absorb matter and maybe also release Hawking radiation. I think that according to the Gullstrand–Painlevé coordinates, space is flowing and the apparent horizon is the region ...
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Why are pseudo-Newtonian potentials used in studies of accretion processes around black holes?

In accretion processes around black holes, pseudo-Newtonian potentials are defined for the the black hole geometry. For examples, the potentials defined by Paczynski-Wiita and Artemova et al. for ...
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Can one see a black hole?

Can one see a black hole on earth? If a black hole does not emit light, how can one take a picture of the black hole itself? There's some discussion that the image composed by the Event Horizons ...
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Is there work underway to push the long baseline capabilities of the Event Horizon Telescope to sub-millimeter wavelengths?

The Max Planck Institute for Radio Astronomy's press release Something is Lurking in the Heart of Quasar 3C 279; First Event Horizon Telescope Images of a Black-Hole Powered Jet shows a stunning ...
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Could we make “tiny black holes”? [closed]

To study the physics of black holes (What we presume as really dense matter) could we not simply simulate that here on earth? What if we took 1 hydrogen molecule and just crushed it with enough force ...
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If a black hole pulls every object in the universe, why there is a light around it?

I've seen some black hole images and I've seen some movies about it e.g(interstellar). I wonder why it has a light around it. Even if I know that light can't escape through it. Can someone enlighten ...
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What is the precession of the star S62? [closed]

What is the angle of precession of the star S62 orbiting the Milky Way supermassive black hole?
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Is there an upper limit on the mass of black hole mergers we can detect?

From the LIGO website, black hole mergers have been observed between black holes with a mass up to roughly 50 $M_\odot$. Are there no black holes with a mass above 100 $M_\odot$ or is this an ...
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How bright would Sagittarius A* be from Earth if it became an Active Galactic Nucleus?

Essentially I'd like to know how bright our central black hole could appear from earth in relation to full moon brightness. Assuming maximum energy output (like when it's gobbling up an entire ...
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How close would the sun have to get to a supermassive black hole to have Jupiter stripped and slingshot into interstellar space?

Please make whatever assumptions are needed. Assume sun approaches black hole on some sort of hyperbolic trajectory. Assume size of supermassive black hole is same as the one at center of our galaxy....
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When did it take place, and what was the cause of the first blackhole in the universe?

When did it take place, and what was the cause of the first back hole in the universe? Does this time precede stars collapsing as a result of old age?
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black Holes and Neutron Stars

if the universe is constantly expanding then the distance between black holes and neutron stars must be increasing. Then What makes them to come under the influence of each other's gravitational ...
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How does a supernova occur when a massive star collapses into a black hole?

My layman's understanding of a supernova explosion is that it's caused by a rebound when a massive star collapses. When the core collapses to a point where neutron degeneracy pressure dominates, the ...
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How fast does a spacecraft have to be to enter a primordial black hole without being torn apart?

If there really is a primordial black hole beyond the Kuiper belt, we can send a probe to the black hole and into it. But how fast must the probe be in order to enter the black hole without being ...
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Can the WISE telescope detect black holes?

Black holes are hot, aren't they? With its infrared scan, could the WISE telescope also detect a black hole? The hypothetical planet beyond the Kuiper belt could actually be a primordial black hole. ...
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Have we ever seen the formation of a blackhole?

So I know that the formation of a supernova has been observed and that we have taken images of blackholes, however, has the formation of a blackhole ever been observed. How do we observe it?
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Jet streams of black holes emit [duplicate]

The speed of light is the upper limit at which conventional matter can travel. However, jet streams propel "material (...) at a significant fraction of the speed of light" (Wikipedia). Let me ...
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What happens with the black hole's mass when a black hole disappears?

If a black hole isn't "fed" by attracted matter, it disappears someday. But how is that even possible? What happens with the mass at its singularity? It can't just disappear or am I wrong with ...
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What observational data convinced Stephen Hawking that Cygnus X-1 was indeed a black hole and caused him to break into Kip Thorne's office?

It's generally easier to be certain an object is a star than a black hole. HDE 226868 is one of our site moderators and a blue supergiant star. The latter has a 5.6 day companion that supplied a ...
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Why don't they make an image of the black hole in the M33 galaxy?

Since we see the Triangulum galaxy M33 from a quite vertical position (contrary to our Milky Way and a bit the Andromeda galaxy) it should be easy to image the black hole in the center of it, shouldn'...
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Can a black hole with the density of water exist?

During an outreach event, the speaker mentioned the fact that black holes weren't necessarily dense objects and that black holes of any density could exist, even black holes with the density of water. ...
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Why does Newtonian physics give the right radius for a black hole?

When computing the distance at which the escape velocity is equal to the speed of light, the result is equal to the Schwarzschild radius. Is this just a coincidence, or is there a physical reason why ...
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How far away are the events that caused the gravitational waves that have been detected?

A certain number of gravitational wave events have been detected. Is it possible to know how far away the mergers that caused those gravitational wave events are?
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Primordial black holes microlensing

Could the movement of a PBH found in the outer solar system by microlensing be totally unpredictable and impossible to track after it was first detected?
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Does a black hole necessarily contain a singularity?

I'm basing this hypothesis on the theories around how an outside observer watching something fall into a black hole will never actually see the thing pass the event horizon. And secondly that from the ...
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How can a singularity actually exist?

Probably a stupid question, but it "bothers" me and I can't find a concrete answer on the internets. When you fall into a black hole, afaik, time slows down for the matter falling in as it gets ...
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What is a thermal distribution of eccentricities?

The abstract of the new (open access) paper in Nature A statistical solution to the chaotic, non-hierarchical three-body problem says: The three-body problem is arguably the oldest open question in ...
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What is the temperature of the black hole?

Are black holes hot or cold? I was thinking because I wanted to know if there any human sustainable temperature so we can travel in it.
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Why does the 70-solar-mass black hole in the LB-1 system challenge current astrophysics?

Recently scientists discovered a large stellar-mass black hole, which (previously) they believed that it shouldn't be possible in our galaxy! Source An international team of scientists say they ...
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Why would a black hole have a disk, but not emit x-rays?

There's a recent paper in Nature about LB-1, a B-class star orbiting a massive black hole. I don't understand how these two parts of the paper can be reconciled. On page 2, the authors argue that the ...
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If we accelerate a neutron star to move at speeds comparable to light would it become a blackhole because of the added energy?

Could a neutron star turn into a blackhole if it is accelerated to near luminal velocities? And if it slows down after a while, does it become a neutron star again?
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Black hole collision animation: What are these extrusions?

In this video uploaded by LIGO Lab Caltech, two inspiraling black holes are depicted. The video's description explains what is shown and can be summarized by: The colored surface is the space of ...
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How much starlight do black holes absorb?

Can it be calculated how much light from other stars a black hole of certain sizes would absorb? And how long will it take for the number of active stars to decrease to the point where Hawking ...
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Could S5-HVS1 conceivably still hold on to any planets?

If the star (S5-HVS1) has been accelerated to 1,700 km/s by a close encounter with the super massive black hole at the centre of our galaxy (Sagittarius A*) what would happen to any planets orbiting ...
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Could a star closely orbit a black hole long enough for the star to have lost 0.5B+ years to time dilation?

I was wondering how stable a close star-black hole system could plausibly be, and thus how much time a star could plausibly miss out on (from an outside observer's perspective) due to being in an ...
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Whats the time dilation difference between the earths reference and (near) the milky way galaxy central black hole? [duplicate]

How much difference in time is there between our time of reference and very near the black hole at the center of our galaxy. I was trying to get answer in terms of something like "1 year in here ...
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Can primordial black holes be found orbiting other stars?

A recent study suggests a that a primordial black hole may be orbiting the sun at and that they can be common near other star systems. What measurements and equipment can perhaps find BH's near ...
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How much damage would collision with a similar mass primordial black hole do to earth?

All this talk of Planet 9 perhaps being a primordial black hole (PBH) made me wonder how dangerous a PBH collision with earth would really be. Specifically, if earth collided with a PBH of 1 earth ...
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In what ways can force be applied to a black hole

Besides gravity I have never heard of another force pushing or pulling a black hole. Does an object falling into a black hole push the black hole when it crosses the event horizon? What happens to the ...
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How would a small nearby black hole be detected and confirmed as such?

This article suggests that there might be a tennis ball-sized black hole orbiting the Sun somewhere beyond the orbit of Neptune. According to the article, observational anomalies of trans-Neptunian ...
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Black holes exhaustion

Can accelerating black holes radiate their mass as an gravitational wave?If that is true maybe dark matter is not something but it is just gravitational waves from an exhausted dense object.

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