Questions tagged [accretion]

Questions regarding the process of a massive body gaining mass from objects around it.

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Can mass loss via accretion occur on stellar remnants?

We know that normal stars can lose mass to a binary companion. But can this happen to neutron stars and white dwarfs? Let's say a stellar black hole is being orbited by a white dwarf or neutron star. ...
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What is the effect of extinction in the accretion disk for black hole mass determination?

I've created a basic model of the accretion disk (AD) by summing up blackbodies following the temperature profile of the AD according to Shakura & Sunyaev (1973) (extensively used in the ...
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What about the magnetic field strength inside of an old accreting neutron star?

As the magnetic field strength outside an old accreting neutron star is thought to be small (about $10^8-10^{10}$ Gauss), what about it inside the star? Because of the superconductivity and ...
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Why doesn't smashing larger and larger bodies incrementally into a rocky planet create a star?

Let's start with a stationary Earth. If we smash a few Mercury-sized objects into the Earth, the Earth begins to accrete mass. Repeat this step with larger and larger objects, until we start impacting ...
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How is angular momentum transferred between a neutron star and its accretion disk?

Accreting neutron stars can either gain or loose angular momentum via interaction with their accretion disks. This leads to either spin-up or spin-down. Which of the two is the case, depends on the ...
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Can white dwarfs have accretion discs too?

Neutron stars and black holes can have discs of accreted matter for they have an extremely high gravitational pull. While white dwarfs don't have such high gravity theirs is of course also extremely ...
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What is the “radiation sound speed” inside an accretion column?

I was trying to read "A New Two-fluid Radiation-hydrodynamical Model for X-Ray Pulsar Accretion Columns" and its follow-up paper both by West et al. and came across a quantity called "radiation sound ...
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Where do rocks come from?

Consider a loose pile of rocks in an early solar system, say a tiny asteroid. As it accretes more and more material, the pressure at its center eventually becomes great enough to collapse the gaps ...
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224 views

Spherical Accretion (Bondi Model)

I have a question. I studied Bondi's model for spherical accretion. I know the assumptions made in the model are big and that they are rarely representative of what happens in astrophysics. What I ...
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Why do black holes choke?

I read that a black hole can sometime "choke" on a star: "...the disrupted stellar matter was generating so much radiation that it pushed back on the infall. The black hole was choking on the ...
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Linear extent of an accretion disk

I have a homework assignment question on accretions discs (essentially an estimation of the number of electron scatterings, but this is just for background). There are a few parameters, one of them ...
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accretion discs in h/lmxbs

High mass x-ray binaries necessarily accrete via wind, no disc accretion? What makes the difference between a hmxb and a lmxb? In what kind of circumstances does an accretion disc form? How does it ...