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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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2 votes
1 answer
148 views

A couple of questions on Hawking radiation

Black holes progressively evaporate due to the emission of Hawking radiation just outside their event horizon primarily in the form of photons. However, there is a small probability that they emit ...
1 vote
0 answers
50 views

Moon mass object hitting Earth vs Moon mass blackhole hitting Earth damage comparison

Doesn't a blackhole do less damage if it goes fast enough to be able to escape fast enought but a moon-mass object if going faster does more damage? Is this true or would a black hole do more damage?
4 votes
2 answers
434 views

What is the "hypothesized lower mass gap" between 2.5 and 5 solar masses?

Searching here for "mass gap" yields nothing yet. Penn State's Black hole or neutron star? LIGO-Virgo scientists find mystery object in 'mass gap' begins: When the most massive stars die, ...
3 votes
2 answers
175 views

Do all black holes, including stellar-mass ones, rotate at nearly the speed of light? Also, what exactly does that do to their shape?

From what I understand, astrophysicists have known for almost a decade that supermassive black holes seem to spin at incredible velocities; nearly the speed of light... In fact, some of the outer ...
2 votes
1 answer
113 views

How ultra massive black holes would " disrupt the accretion discs that feed them" beyond some upper limit to their masses?

According to this, How big could a black hole get recent studies suggest that UMBHs cannot physically grow much beyond this (10 billion solar masses) anyway, since they would then begin to disrupt ...
17 votes
4 answers
10k views

Is there a maximum size for a black hole?

As far as I understand it black holes radiate Hawking radiation and probably gravity waves, which over time causes them to lose mass and eventually evaporate after almost unfathomable amounts of time. ...
0 votes
0 answers
136 views

My question is about the warp of time and space near black holes

I have seen some recent articles indicating that there might not be a singularity at the center of black hole at all1. Have further heard commentary about black holes that spin incredibly fast. I was ...
12 votes
4 answers
5k views

How can a black hole have a charge, or be charged?

So-called 'hairless' black holes (no-hair theory, or theorem?) , which is what real black holes are, can be described by just three characteristics: Mass, spin, and charge. It is easy enough to ...
2 votes
3 answers
300 views

Is there evidence against a Universe Black Hole?

As far as I know, the critical density of our observable universe coincides with the density of a huge black hole of the same radius. It could be a BH expanding at the speed of light and growing in ...
2 votes
2 answers
2k views

What if hypothetically Ton 618 could have been a star

Assuming Ton 618, the largest ultra massive black hole wasn’t the result of feasting on near by matter but was hypothetically once a single star body. How large in terms of size would TON 618 have ...
3 votes
2 answers
206 views

Black hole explosion due to rotation [duplicate]

I am not an expert, I was just thinking about this scenario: A black hole that, for some reason, will start spinning faster and faster. Is it theoretically possible that the rotation becomes so fast ...
3 votes
1 answer
130 views

Can a quasi-star develop a stable crust?

Could a quasi-star potentially develop a stable outer layer or crust during its early stage of formation if it were to be bombarded with substantial amounts of matter, coexisting with its core and the ...
11 votes
1 answer
267 views

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 ...
6 votes
2 answers
1k views

What are the most up to date, accepted, evolution stages of big stars that end in compact objects or a planetary nebula?

There are numerous charts and diagrams showing the stages of stellar evolution, as: or among many more (you can find several after googling a little), for example. When I studied my B.Sc. on Physics,...
23 votes
3 answers
13k views

Maximum spin rate of a black hole?

I have just been watching a podcast called "Deep Astronomy" and the discussion was about a super fast spinning black hole discovered with the NuSTAR space observatory. This black hole was ...
13 votes
2 answers
7k views

Observable universe equals its Schwarzschild radius (event horizon)?

The estimated age of the universe is 14 billion years. The estimated Schwarzschild radius (event horizon) of the observable universe is 14 billion light-years. What are the ramifications?
1 vote
0 answers
86 views

What would happen if a low-mass primordial black hole was captured by a brown dwarf or planet mass object?

Prompted by a recent PBS SpaceTime video The video in question discusses what would happen if a low-mass (asteroid-mass) primordial black hole were captured in the core of a Sun-like star (a so-called ...
7 votes
1 answer
252 views

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 ...
21 votes
4 answers
6k views

What would happen if a small black hole fell into a star?

Let's say you created a cannon that can shoot small black holes and you shoot it at some star. Would the star just turn into a black hole silently? Or rather first destabilize and produce a last ...
1 vote
0 answers
102 views

How long could a world like the Moon survive with an Earth mass black hole in the center?

I asked that question at the worldbuilding stack exchange. https://worldbuilding.stackexchange.com/questions/202273/how-long-could-a-planet-or-moon-survive-if-it-had-an-earth-mass-black-hole-withi ...
6 votes
1 answer
801 views

Could an hypothetical hidden black hole companion to the sun be revealed by proper motion data?

If the Sun were in a binary star system with a black hole companion, the Sun would be orbiting the black hole, and this should be reflected in a change in the observed proper motion of nearby stars. ...
2 votes
2 answers
451 views

How could lithium burning take place in a quasi-star?

According to Begelman et al. (2008), one of the most distinguishing features of the hypothetical quasi-star is that it's supported by radiation pressure from the accretion disk of the black hole in ...
14 votes
3 answers
3k views

Can a small black hole orbit a large star?

I recently read about the discovery of a tiny black hole (with only three times the mass of the sun) nicknamed ‘The unicorn’ about 1500 light years from earth. This got me thinking, can this black ...
2 votes
2 answers
344 views

The consequences and the mechanisms of a shift of the Earth away from the sun

First premise: I have already made this question in the worldbuilding section, but since it is a very specific question many have recommended me to write in the astronomy section so here we are. ...
0 votes
2 answers
215 views

Why do we not call black holes black stars or dark stars?

I've never understood why the term black holes are widely used to describe what is actually a black star or dark star. I mean why name something just because of its extreme space curvature effects? In ...
7 votes
2 answers
342 views

Would gravitational waves be subject to external gravitational perturbations?

Given that the gravitational wave detected by LIGO was a very weak echo of a very distant event, could it have been "deviated" and distorted on its way here by a sufficiently massive black hole in ...
9 votes
3 answers
3k views

Binaries consisting of a black hole and a non-black hole?

Are there any known binary systems in which one member is a black hole and the other is not a black hole (main sequence star, giant, neutron star, white dwarf, whatever)? Googling seems to turn up ...
2 votes
3 answers
422 views

How can Kerr black holes have a 'speed limit' to how fast they can spin?

Obviously, the speed of light is a presumed limit, at least for 'physical' objects moving 'within' ('through'?) spacetime, but... In recent news some scientists believe they have figured out the ...
15 votes
7 answers
11k views

How did the Milky Way quasar not disrupt life on Earth?

According to most sources of information I have found (A Quora answer and books), when galaxies become quasars, they destroy all life in their host galaxy, as they output so much radiation that they ...
-2 votes
3 answers
256 views

Can black holes even exist [if mass cannot be retained near the collapse threshold]?

A black hole happens because enough material mass exists in an area to create a gravitational field strong enough that nothing escapes (including light). This gravity also exceeds the strength of ...
1 vote
1 answer
99 views

Amount of black holes over time

Hello the number of black holes is much bigger than the number of black holes in the past right?Let $b$ be the number of black holes in the universe.Obviously $\frac{db}{dt}>0$ but what about $\...
2 votes
0 answers
81 views

JWST Early Black Holes: Gas Collapsed To Metallic Hydrogen Core?

I was reading an article about early black holes found by JWST at Redshift 9. And saw that there was wonder at how large amounts of gas could collapse into a black hole as a theory. So my question is ...
10 votes
2 answers
614 views

Are gravitational waves emitted equally in all directions?

I have a question regarding gravitational waves that I can't figure out. Hope some wise minds here can help a simple amateur without technical or scientific education. Two black holes rotating around ...
2 votes
1 answer
122 views

Black hole collision

In a situation where 2 black holes are close to colliding, but do not collide, can one black hole free/steal matter from the other in passing if the event horizons brush?
23 votes
3 answers
3k views

From an outsider's perspective, how can a black hole grow if nothing ever crosses the event horizon?

Due to time dilation, an outside observer never sees a falling object actually cross the event horizon. I'm not referring to the optical illusion of red-shifted light making objects appear to fade ...
45 votes
2 answers
48k views

How does a neutron star collapse into a black hole?

We know the spectacular explosions of supernovae, that when massive enough, form black holes. The explosive emission of both electromagnetic radiation and massive amounts of matter is clearly ...
44 votes
5 answers
6k views

How do we know that black holes are spinning?

How is it possible to know if a black hole is spinning or not? If a planet is spinning, you can see it clearly but you can't really see a black hole. Next thing would be that matter interacts with ...
67 votes
2 answers
14k views

If two black hole event horizons overlap (touch) can they ever separate again?

Hypothetical question based on my understanding that two event horizons that overlap (touch) can't ever separate again: Imagine a 1 billion solar mass black hole (so the event horizon is massive and ...
77 votes
2 answers
11k views

Can gravitational waves pass through a black hole?

As the title says, what happens when a gravitational wave approaches a black hole? I would presume that something interesting happens because of the way spacetime works near black holes but I have no ...
55 votes
9 answers
11k views

Does matter accumulate just outside the event horizon of a black hole?

My understanding is that time slows and approaches stopping when approaching the event horizon of a black hole. I have seen this explained several places, including a brief explanation in the last ...
3 votes
4 answers
3k views

How do stars 1 billion times the volume of our sun form and can they become black holes?

UY Scuti is a star 1 billion times the volume of our sun. A billion solar mass black hole formed 750 million years after the Big Bang. Could it have formed from a star like UY Scuti? Rare black hole ...
0 votes
2 answers
148 views

Possibility for black holes having negative energy

new to the community here. The question I have is whether black holes can possibly contain negative energy of any sort? It’s not a carefully thought-out question as space is not my bailiwick.
7 votes
2 answers
3k views

Is there a limit to the Schwarzschild radius?

The Schwarzschild radius is a way for us to calculate the extent to which something has to be shrunk in order for it to become a black hole but I was wondering is there a limit to the object that we ...
1 vote
1 answer
103 views

Death of a Black Hole ≠ Rebirth?

So we all know that Stephen Hawking proved that Black Holes do evaporate overtime through hawking radiation. But that energy is released in very discrete amounts and there will be a time in the ...
0 votes
1 answer
116 views

Will an overspun black hole be white?

I recently watched a Kurzgesagt video about destroying black holes. In the video, they mentioned that you can (theoretically) "overspin" a black hole to remove its event horizon, thereby ...
5 votes
1 answer
3k views

What is a "Gentle Giant" Black Hole?

I have seen articles about the Milky Way's "gentle giant" black hole. For example: https://nypost.com/2022/05/12/image-of-gentle-giant-black-hole-at-milky-ways-center/ https://www.reuters....
1 vote
1 answer
299 views

The event horizon of a black hole

According to https://www.nationalgeographic.com/magazine/article/black-holes-einstein-star-eaters', when something crosses the event horizon of a black hole "A person watching from the outside ...
0 votes
0 answers
59 views

Question about how it's possible for black holes to have gravity and a possible resolution [duplicate]

1. Assumptions 1.a: gravity propagates at c (maximum) 1.b: gravitational fields cause time dilation 1.c: escape velocity at the event horizon is c 1.d: gravity "warps" space-time, but in ...
9 votes
1 answer
2k views

If you were on a planet orbiting a star that has a black hole companion, could you see light from your host star bent 180 degrees?

I realize that there is a distance from a black hole where photons can orbit. I understand that this orbit is very unstable, but I am concerned with photons just outside this range. Could the black ...
32 votes
3 answers
14k views

Can our Sun become a black hole

Does every star become a black hole? Is there any probability that our sun can become a black hole? If yes then is it on its way to become a black hole? what is the current state of sun as per the ...

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