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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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Time Dilation and Particle Decay

I am teaching myself astronomy and I'm working on a basic problem regarding time dilation around black holes. The question is basically this: if a neutron were ejected from a nucleus at a distance of ...
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Has the Penrose process ever been linked to an observed phenomenon in some way?

This answer mentions the Penrose process as a potential mechanism that could change the axis of the orbital angular momentum of an accretion disk around a black hole away from the original axis of the ...
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How far away was the binary black hole that produced GW170729?

GW170729 was gravitational wave signal's detected by the Virgo and LIGO detectors. I read the following in a news report: Known as GW170729, in accordance with the date of its discovery (in US ...
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Astrophysical Jet Size?

I am wondering about what is the estimated size of astrophysical jet that shoots out from a black hole, I don’t know if it is determined by the size of a black hole. What would classify a black hole ...
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What fractions of matter are retained and displaced by quasars?

Following on from a query concerning quasar mass, what fraction of matter is ejected compared to matter that is lost to the BH? Is there a graph that describes the fractions of the mass of quasars ...
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How does the size of a naked black hole effect its photon sphere?

What effect does the size of a black hole have on the size or density of the photon sphere and it's proximity to the horizon? For example: A person is in space looking at 2 black holes, one of them ...
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Could a closely orbiting pulsar be used to study a black hole?

If we were to locate a pulsar in a close elliptical orbit around a black hole, could this reveal significant information about the black hole (e.g. time dilation / structure)? Could this even tell us ...
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Can we resolve the centers of Milky way's satellite galaxies now?

Two dwarf satellite galaxies of our galaxy have large $\frac{\text{diameter}}{\text{distance}}$ values. And one of them, Canis Major Dwarf, is 8kpc away which is the same with our distance to the ...
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Can we determine where the north and south magnetic poles are on stars and black holes?

The question is related to this about Are there collected data about the direction of rotation of black holes and the direction of the magnetic field?. Perhaps it is observable for pulsars?
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Does the Canis Major Dwarf Galaxy have a black hole at its centre?

I am just wondering: is there a potential galactic centre out there that's very close to us? I know that CMDG is irregular, but can it still contain a black hole at the centre?
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The black hole binary that was detected by advanced LIGO - how do such hypergiant binaries form?

With today's announcement of the historic detection of gravitational waves from the merger of 36 solar mass and 29 solar mass black holes 1.3 billion light years away, one can not help but wonder how ...
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How long a photon stay suspended in orbit around a black hole?

Can a black hole free from an accretion disk collect photons in the photon sphere in a prolonged stable orbit? Could enough photons be in orbit to shade the actual black hole with light? Would a ...
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How do black hole spinning at speed of light expose its singularity?

Black hole can spin very rapidly something about conserving momentum once a massive star used up its fuel and collapsed under it own weight, if black hole can spin at speed of light it could expose ...
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What can I learn from, or notice in the LIGO Orrery video?

The Ars Technica article Physicists detected gravitational waves from four new black-hole mergers notes that This brings the total number of events detected by LIGO and Virgo to 11. It also has a ...
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How many fluorescent iron lines?

An iron atom has 26 electrons. Its 6.4 KeV line is a fluorescent line. There are 6.7 and 6.9 KeV lines also. How do they form? An electron from which energy level fills in which energy level? Is there ...
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Where can I get radial velocity data on HDE 226868/Cygnus X-1 and A0620-00?

I want to plot the radical velocity curve of HDE 226868/Cygnus X-1 or A0620-00 from REAL data. Where could I get the full data from spectroscopy and photometry?
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black hole horizon encompassing massive particles from an outside observer's perspective?

I've seen a few posts on the internet which seem to suggest that an observer never seeing a particle crossing the horizon is an idealization for a massless particle. If the particle is massive some ...