Wikipedia:Reference desk/Archives/Science/2019 April 27

= April 27 =

Can neutron stars be broken up?
I haven’t heard of any fundamental reason why some type of explosion or maybe tidal forces couldn’t tear up a neutron star.Rich (talk) 04:03, 27 April 2019 (UTC)


 * How about a close interaction with another object as massive and dense as it (like another neutron star), or even denser (such as a black hole) ? I can imagine tendrils of neutrons spinning out into space from a collision, much as with a galactic collision. Tidal forces would then come into play. As for explosions, what would be the source of such a powerful explosion ? A supernova in a binary system, where the other star is a neutron star ? I'm not sure if even that would have much effect, due to the much lower density of the supernova gasses relative to the NS. It would be like blowing a hair dryer on a bowling ball and expecting it to break up.SinisterLefty (talk) 05:20, 27 April 2019 (UTC)


 * Just whack that neutron start with another neutron star going at 0.99C. Better yet, hit it with an antineutron star. And have each one rotate at just slightly less than the spin needed to cause them to fly apart. Physics question: What would cause the largest bang, north pole hits north pole? North pole hits south pole? Equator hits equator with same spin? Equator hits equator with opposite spin? --Guy Macon (talk) 05:58, 27 April 2019 (UTC)


 * Ramming 2 neutron stars together at close to the speed of light might actually create a black hole. Still, I'm sure plenty material would escape the collision. SinisterLefty (talk) 18:47, 27 April 2019 (UTC)


 * WP:WHAAOE: Neutron star merger. Although I think I found an error in that article. It says the merger will produce a black hole if the mass of the remnant exceeds the Chandrasekhar limit. But, it looks like the correct limit is actually the Tolman–Oppenheimer–Volkoff limit. The former is the limit for forming a stable white dwarf. Am I missing something? I want to confirm this before making an edit. --47.146.63.87 (talk) 23:18, 27 April 2019 (UTC)


 * Yes, but note that that article considers a merger at "normal" velocities. Since there's no reason to think neutron stars would ever be travelling at near the speed of light, they didn't consider that scenario, where it wouldn't be the mass alone compacting it, but also the huge momentum. SinisterLefty (talk) 02:16, 28 April 2019 (UTC)


 * What if sufficiently many charged particles, either positive or negative but not both, were captured by the neutron star to cause it to overcome gravitation attraction? Would a small piece of neutron star that was broken off explode violently?Rich (talk) 03:04, 4 May 2019 (UTC)


 * Then the protons or electrons would repel each other, but not the neutrons. If the charge was high enough to overcome the massive gravity well, then the protons or electron would escape into space until that was no longer the case. Of course, getting to this situation in the first place seems to be impossible. A collision with a large chunk of antimatter might as well be considered, and that does seem to have the potential to blow any neutrons that avoid annihilation into space. SinisterLefty (talk) 12:47, 4 May 2019 (UTC)

Geography question—What counts as bordering? (Samara Oblast)
The Samara Oblast article states that "[Samara Oblast] borders Tatarstan in the north, Orenburg Oblast in the east, Kazakhstan (West Kazakhstan Province) in the south, Saratov Oblast in the southwest and Ulyanovsk Oblast in the west."

Now, if we look on a map, we can see that, indeed, the southernmost corner of the oblast does reach Kazakhstan at one geometric point; however, does it, geographically speaking, constitute an actual border like the one the oblast has with the rest of territories listed (Tatarstan, Orenburg etc). And, if it does, what's the length of it? --Samuel L. Russell (talk) 08:36, 27 April 2019 (UTC)


 * I'm not sure if it answers your specific question, but the quadripoint article has some information on this kind of issue (see what it says about the border dispute in the section "Four-nation quadripoints", for example). PaleCloudedWhite (talk) 08:57, 27 April 2019 (UTC)


 * For comparison, our article Arizona avoids the word “borders” by saying “Arizona shares the Four Corners region with Utah, Colorado, and New Mexico; its other neighboring states are Nevada and California to the west and the Mexican states of Sonora and Baja California to the south and southwest.” The article New Mexico does it the same way. The articles Colorado and Utah say they border some states and “touch” the other one. Loraof (talk) 19:02, 27 April 2019 (UTC)


 * For that single point of contact, what kind of border control is used there, if any? ←Baseball Bugs What's up, Doc? carrots→ 00:04, 28 April 2019 (UTC)
 * It would presumably be the same as at any other part of the Russia–Kazakhstan border. It's unlikely that there are any border controls between the three Russian oblasts, so the fact that three of them happen to meet at that point on the border with Kazakhstan is of no relevance to the latter. {The poster formerly known as 87.81.230.195} 2.122.2.132 (talk) 19:24, 28 April 2019 (UTC)