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Comment by QueensGambit | Hacker News Reader

This newly detected neutron star is 333,000 times the mass of the Earth and 2.17 times the mass of the sun. But the star is only about 15 miles across. This is close to the limit of how much mass a compact object can contain before it crushes itself into a black hole.

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> This is close to the limit of how much mass a compact object can contain before it crushes itself into a black hole.

Obviously it's time for bed because reading this makes me want to toss a quarter in it to see what happens.

Assuming you are starting from orbit wouldn't you have to give that coin quite a "toss" to get it to change its orbit so as to hit the surface? No atmosphere to help...

Not if you’re far enough away.

It would get shred to fundamental particles/waves. Then its electrons would fuse inside the nucleus to form a neutron gravy.

I'm curious as well, for example to imagine how the event would unfold, as it would not be the direct remnant of a supernova. For an observer, would the neutron star seem to just disappear? Where would be the horizon and what would it look like as it suddenly appears?

I'm not a physicist, but I _think_ to my understanding what you would see is a collapse that would slow down and get more and more red-shifted, as the photons from the collapse take longer and longer to get to you (and are robbed of more and more energy, hence the red-shift).

So what you would see is more of a slow fadeout as the object shrinks and gets redder and dimmer, until you can't see anything at all. In the limit as the object gets smaller and the photons get dimmer, you end up with something that emits no light and is the size of the black hole silouette.

Saying that's what you would see is a bit like saying that if you push something it will keep moving forever. It's the physicist's answer, assuming ideal conditions.

In reality, the initial collapse probably won't include all the mass of the object, including any dust or gas orbiting nearby it. So your lovely "fading from sight" black hole will be there, but obscured by the raging maelstrom (always wanted to use that word) of material now circling the plug-hole around it and heated to $DEITY knows what temperature.

ill throw equal quantity of vacuum to see if it counters your quarter :D

Imagine a far future game where bored teenagers grab the family spaceship, find a neutron star just below the blackhole limit, and throw things into it until it makes the switch. How fun would that be?!

You couldn't actually do that. Time dialation means the thrown object would never actually hit the neutron star from your POV and the black hole would never form.

ok. black hole and neutron star are between a silver line. I understand the idea of switch you spoke about.

throw void into black hole (becomes neutron star)

throw little piece of black hole into neutron star (becomes black hole)

aah. little theory.

blackhole mass can be used to convert neutron star to a blackhole.

A balance between blackhole and neutron star.

You can turn a neutron star into a black hole, but you cannot turn a black hole into anything else, only make them bigger.

They actually measured a mass of 2.14

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