I’m trying to understand something here that is well outside my area of expertise. The little factoid came across my desk this morning that a neutron star is so dense that on earth a teaspoonful would weigh nearly a billion tons…?
Q’s: What cosmic occurrences or lack there of create neutron stars?
Because of their overwhelming gravitational pull how close could a prob get to one?
What is the closest one to us?
And are there hubble photo’s of neutrons stars?
Finally, the material the make up the stars…the dense material, what exactly is it?
When a star runs out of fuel it will throw off most of it’s mass leaving really just it’s core, if this remianing mass is is inbetween ~1.2 solar masses and ~3 solar masses the degenaracy pressure caused by electrons being repulsed by atomic protons will be less than the attraction due to gravitation and the protons and electrons (plus an antineutrino) will combine via the process of reverse beta decay to form neutrons. Neutron stars are made out of neutrons thugh IIRC they probaly have a ‘crust’ of protons and electrons.
You can get as close as you like to a neutron star as long as you don’t mind being crushed, with a few gross approximations and back of the envelope calculations, I’d say don’t go closer than approx. 2 x 10[sup]9[/sup] m to a small neutron star.
Essentially, the material in the star wants to go to its lowest energy state (like all good particles). So as fusion progresses, iron, the last basic product of fusion, starts accumulating like trash in the core of the star.
But it’s a LOT of iron. So much that it wants to collapse in on itself completely. What stops it (and all ordinary matter, for that matter)? Electrons repel each other. So that keeps things stable for a while. Eventually, though, even that force isn’t enough to prevent collapse, and the protons and electrons collapse together to form a lower-energy mush of neutrons. What keeps the neutrons from collapsing further? The basic fact that particles don’t like to occupy the exact same space/state.
At this point, you have a neutron star that is about the size of a city, but unbelievably massive. If you had a bit more mass than this, to overcome even the neutrons’ desire to stay away from each other, then the whole thing will collapse into a black hole.
There’s also a type of star between neutron stars and black holes called a “strange star”. Instead of being composed of neutrons, it’s composed entirely of strange quarks. Astronomers have even found possible candidates which were once thought to be neutron stars.
Good layman’s explanations already posted, so I’ll just add:
Read Larry Niven’s short story “Neutron Star.” It’s a classic “hard SF” short describing an explorer’s trip to the eponymous astronomical phenomenon, and the wierdnesses that inhabit its vicinity.
Aslightly more interesting type of neutron star, young and rotating, with jets of energy from the magnetic poles- a pulsar
and a dramatic high energy magnetar-
(a graphic image only)
Is that right? Neutron stars are between 1.4 and 3.0 solar masses. Less, and they’d be white dwarves; more, and they’d be black holes.
So does a star really lose 90% of it’s orignial mass during a supernova? Does the matter comprising the neutron star only account for 10%? And are there really that many stars with 15 to 30 times the mass of the sun?
Yes, for a neutron star it’s a balance between having enough mass to overcome electron degeneracy and having not enough to collapse further, though in theory neutron stars can be bigger than 3.0 solar masses (4.5?), but realistically this is not possible.
As I said earlier a neutron star is basically made out of the core of a star and all the other matter, which makes up most of the mass is thrown off. Though 15-30 SM would put a star on the largish size, ther are certainly no shortage of stars in this range, esp. when you consider how many stars there actually are in total.
eburacum45 or others, do you know if that star paired with the crab pulsar in the photos is actually a companion star (or just “in the way” of the photo)? Is the crab pulsar in a binary system?
I’ve never heard that the Crab pulsar is binary, and if it were, we would certainly know it (a companion would need to be included in models of the pulsar timing).
As for quark stars (aka strange stars), they’re a strong theoretical possibility, and there are a few candidate objects, but they’re still pretty far from proven. At the very least, it looks like there’s a very narrow range of initial masses which will produce one (rather than a neutron star or black hole). And they’re not composed entirely of strange quarks (that would give them a friggin’ huge charge). If I recall correctly, they’re composed of equal parts of up, down, and strange quarks (as opposed to the more typical 2:1 down:up for neutrons).
