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.
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...
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.
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.
2. What would be medieval would be a superstitious reaction to units of measurement as if they were purity religion cult signifiers rather than simple rational concepts to be converted between at will, depending on the task at hand.
Who do you think ruled Britain until 410AD and give the English their mile, which is simply the word for "1000" in Latin?
And I think that the press release is in error here. There was no radius measurement proposed in the Nature Astronomy paper. However, the radius in the press release is far to large. See:
Something on the order of 6-10 miles for a 2.14 M neutron star is much more appropriate.
Notice that this measurement may rule out some of our models (mostly the gray lines on the left of the chart) that don't predict neutron stars this massive.
The "correct" conversion to (modern) miles would be 20, both because 30 has only one significant digit and because it makes more sense to round 18.x to 20 than to 15.
OP here. I got that number from the CNN article [1], which they probably quoted for their US audience. It is neither medieval, nor meant to be accurate to the decimals.
I love HN comments, but this reminds me of the flame war threads that has very little relationship to the original subject :) Cheers!
I'd be more inclined to use leagues, which, when used at sea, in the English-speaking world, are usually three nautical miles or five point five five six kilometers.
So about 5.39 leagues across.
Since we use ships when we go to space and sea, I like the idea that space ships are naval.
When I read the miscorrection of kilometres I was hoping someone would convert the various quantities to fit the oft' overlooked furlong–firkin–fortnight [1] measurement system.
