Comments on: Record-Setting Neutron Star Shows Astronomers What It's Made of

By: cag

cag — Sun, 10 Apr 2011 06:01:17 +0000

People like nick are all too common in the world. I’m convinced 90% of the population does not grasp the basics of the Universe. Sad.

By: Dwayne Stephenson

Dwayne Stephenson — Sun, 31 Oct 2010 18:48:36 +0000

Plus, it’s impossible to imagine how a supernova could explode in such a way that the neutrons would magically separate from the electrons and protons to form their own celestial mass.

By: Richard

Richard — Fri, 29 Oct 2010 19:15:21 +0000

The high pressures of the collapse of the interior of a supernova drive the endothermic process

e + p -> n + neutrino.

So yes, “electrons and protons do come together to form neutrons” ( plus a neutrino which escapes the supernova.) Look up “inverse beta decay,” or “electron-capture.”

By: astrohobo

astrohobo — Fri, 29 Oct 2010 04:27:31 +0000

Nope, nick, you are totally out to lunch here.

The core of a massive star is already compressed to maximum atomic density such that degenerate electron pressure (the Pauli exclusion principle) is holding it up . This special form of matter is what the white dwarf companion star is made of. When the core reaches the critical mass of 1.4 times solar, and when the degenerate pressure is no longer aided by heat from internal fusion because you can’t get energy out of iron 56 (which the fusion process has built up the atoms into), then it becomes energetically advantageous for the electrons and protons to combine into neutrons (the technical term is neutron drip).

Note that in ordinary hydrogen fusion, protons and electrons turn into neutrons all the time… in fact, that’s how you get neutrons in the first place. You don’t create neutron/anti-neutron pairs out of raw energy like you can make protons and anti-protons as well as electrons and positrons. To make a helium nucleus consisting of two protons and two neutrons, you start with 4 hydrogen atoms consisting of 1 proton and one electron each.

By: nick

nick — Fri, 29 Oct 2010 01:47:10 +0000

Hate to be pedantic (okay, that’s a lie) but electrons and protons don’t come together to form neutrons, neutrons are the chargeless particles already existing inside normal matter that help add mass to the nucleus of an atom – they were discovered when atoms had more mass than the protons and electrons alone could account for, and the amount of neutrons in an atom determines what isotope of an element you have, whereas the amount of protons determines which element you have. (and for the extra curious, the electrons and how they ‘orbit’ determine how atoms bond, or don’t, with one another)

The electrons and protons were probably lost in the nova. A neutron star is composed of neutrons that have overcome their normal repulsion and are packed together as densely as we can currently imagine matter being (can’t get any closer due to the Pauli exclusion principle – at least as far as we are currently aware).

Though, it does sound quite logical that you mash some protons and electrons together to get neutrons (i.e. positive + negative = neutral). But neutrons are made up of three quarks, as are protons (though in different configurations, thus the neutral and positive charges, respectively), and electrons themselves are indivisible (as far as we are currently aware).