kerbiloid Posted February 21 Share Posted February 21 They should differ. They have originated from two different monkeys, a male and a female. Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted February 27 Author Share Posted February 27 White dwarf eats planet with unexpected results https://www.cnn.com/2024/02/26/world/cannibal-star-metal-scar-scn/index.html Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted February 27 Share Posted February 27 5 hours ago, JoeSchmuckatelli said: White dwarf eats planet with unexpected results https://www.cnn.com/2024/02/26/world/cannibal-star-metal-scar-scn/index.html It has been reproduced in a lab test long ago. See the dark metal spot at the top. Spoiler Disclaimer: Do not repeat it at home. Quote Link to comment Share on other sites More sharing options...
Vanamonde Posted February 27 Share Posted February 27 Neutron stars are commonly described as being entirely converted into neutrons, but for metals to be present at least some of the surface matter would have to remain in atomic form with protons present and associated with neutrons in nuclei. Is that common for neutron stars? It's not hard to believe but I've never heard it mentioned before. How deep is the normal matter "crust"? Quote Link to comment Share on other sites More sharing options...
RKunze Posted February 27 Share Posted February 27 1 hour ago, Vanamonde said: Neutron stars are commonly described as being entirely converted into neutrons, but for metals to be present at least some of the surface matter would have to remain in atomic form with protons present and associated with neutrons in nuclei. Is that common for neutron stars? It's not hard to believe but I've never heard it mentioned before. How deep is the normal matter "crust"? If you are referring to the "metal scar" mentioned by @JoeSchmuckatelli then the star in question is a white dwarf and not a neutron star. White dwarfs are dense, but still formed of "normal" (at least compared to the stuff neutron stars are made of) matter. If you were posing a new question: According to most models, neutron stars have a thin crust of more or less "normal" matter (nuclei and electrons), with the nuclei getting gradually more neutron rich with increasing depth (and pressure), until the pressure gets high enough to force all of the electrons into protons. And maybe the inner core of large neutrons stars may be composed of even more exotic matter than that. Quote Link to comment Share on other sites More sharing options...
Vanamonde Posted February 28 Share Posted February 28 Oh, I misread it. This is what happens when you've had the Death Cold for 1.5 weeks. Even so, if it's not a neutron star why isn't convection dispersing the metals? Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted February 28 Share Posted February 28 7 minutes ago, Vanamonde said: Oh, I misread it. This is what happens when you've had the Death Cold for 1.5 weeks. Even so, if it's not a neutron star why isn't convection dispersing the metals? Apparently it's pinned in place by magnetic fields. Quote “This scar is a concentrated patch of planetary material, held in place by the same magnetic field that has guided the infalling fragments,” said Landstreet, also affiliated with the Armagh Observatory and Planetarium. “Nothing like this has been seen before.” Quote Link to comment Share on other sites More sharing options...
magnemoe Posted February 28 Share Posted February 28 9 hours ago, RKunze said: If you are referring to the "metal scar" mentioned by @JoeSchmuckatelli then the star in question is a white dwarf and not a neutron star. White dwarfs are dense, but still formed of "normal" (at least compared to the stuff neutron stars are made of) matter. If you were posing a new question: According to most models, neutron stars have a thin crust of more or less "normal" matter (nuclei and electrons), with the nuclei getting gradually more neutron rich with increasing depth (and pressure), until the pressure gets high enough to force all of the electrons into protons. And maybe the inner core of large neutrons stars may be composed of even more exotic matter than that. You also has something named quark stars who is even denser than neutron stars. Makes me wonder if it could exist some state of matter who is even denser and make up at least stellar black holes? Or is it some relativistic reason why this don't work? Quote Link to comment Share on other sites More sharing options...
farmerben Posted February 28 Share Posted February 28 15 hours ago, Vanamonde said: Neutron stars are commonly described as being entirely converted into neutrons, but for metals to be present at least some of the surface matter would have to remain in atomic form with protons present and associated with neutrons in nuclei. Is that common for neutron stars? It's not hard to believe but I've never heard it mentioned before. How deep is the normal matter "crust"? I think a good fraction of the matter is protons. The neutrons regularly beta decay and the protons regularly reverse beta decay. The electrons may be modeled as a fermion gas distributed throughout the star and not bound to any nucleons. Quote Link to comment Share on other sites More sharing options...
tater Posted February 28 Share Posted February 28 Not quite science, but: TIMED is active (for 22 years), the COSMOS a derelict, but original mission for TIMED was supposed to be 2 years. We really need to make stuff that can deorbit itself. Quote Link to comment Share on other sites More sharing options...
darthgently Posted February 28 Share Posted February 28 17 minutes ago, tater said: Not quite science, but: TIMED is active (for 22 years), the COSMOS a derelict, but original mission for TIMED was supposed to be 2 years. We really need to make stuff that can deorbit itself. At the risk of starting WWIII, could a ground based military laser system be used to slowly ablate the prograde portion of a derelict satellite such that the mass and energy ablated would cause a retrograde acceleration and lower the orbit thus quickening its demise? Someone, somewhere has looked at this Quote Link to comment Share on other sites More sharing options...
tater Posted February 28 Share Posted February 28 I expect some nations to be irresponsible, but even TIMED has no propulsion at all. Seems like any modern (it was flown 2002) sats should have hall thrusters or something sufficient to deorbit. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted February 29 Share Posted February 29 14 hours ago, darthgently said: At the risk of starting WWIII, could a ground based military laser system be used to slowly ablate the prograde portion of a derelict satellite such that the mass and energy ablated would cause a retrograde acceleration and lower the orbit thus quickening its demise? Someone, somewhere has looked at this Airborne ones, in the thin air above the clouds. Either planes or airships. Having a stratospheric anti-satellite laser blasting airship is a thing... *** Large solar panels are also sails. The larger they are, the better they brake. Quote Link to comment Share on other sites More sharing options...
DDE Posted February 29 Share Posted February 29 23 hours ago, darthgently said: At the risk of starting WWIII, could a ground based military laser system be used to slowly ablate the prograde portion of a derelict satellite such that the mass and energy ablated would cause a retrograde acceleration and lower the orbit thus quickening its demise? Someone, somewhere has looked at this "Laser broom". Explored at Sandia and the Russian space surveillance center at Altai. 8 hours ago, kerbiloid said: Airborne ones, in the thin air above the clouds. Either planes or airships. Nope, AFAIK they aimed for groundside systems... much like their current observatories. Alright, my own question. When do Li-ion batteries blow up? Specifically, mechanically undamaged but previously exposed to temperature swings and likely low-quality to begin with. My dad had a powerbank puff up and explode once he threw it on the floor. In the middle a busy mall. The security were not amused. (Or, at least, so he says) And now I'm staring suspiciously at another freshly recharged powerbank on my shelf. Quote Link to comment Share on other sites More sharing options...
darthgently Posted February 29 Share Posted February 29 54 minutes ago, DDE said: When do Li-ion batteries blow up? Specifically, mechanically undamaged but previously exposed to temperature swings and likely low-quality to begin with. General consensus is: Never leave them charging unattended. Replace at first sign of swelling or getting abnormally warm while charging. Never trust off brands, and even be suspicious of "quality" brands. There have been many cases of RC modellers starting fires in their houses with unattended chargers. I'd like to see a power cutoff to the charger based on temp probe reading. A separate unit with a temp sensing mat for charging all batteries (phones, rc batts, cordless tool, etc.) or similar. Power density is power density. People should think of rechargeable batteries like little bottles gasoline and charging them should give them the same sense of caution that heating little bottles of gasoline would, imho. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted February 29 Share Posted February 29 4 hours ago, DDE said: Nope, AFAIK they aimed for groundside systems... much like their current observatories. These ones are. But in 1980s they were saying, how cute is shooting the incoming warheads from below, rather than ground targets from top. Quote Link to comment Share on other sites More sharing options...
darthgently Posted February 29 Share Posted February 29 To be clear, my initial question was about deorbiting defunct drifting stuff by lowering its orbit via careful ablation derived reaction, not star wars anti-missile or aggressive antisatellite applications. Has it been successfully demo'd? Does it make sense? Quote Link to comment Share on other sites More sharing options...
DDE Posted February 29 Share Posted February 29 1 hour ago, darthgently said: To be clear, my initial question was about deorbiting defunct drifting stuff by lowering its orbit via careful ablation derived reaction, not star wars anti-missile or aggressive antisatellite applications. Has it been successfully demo'd? Does it make sense? The Star Wars stuff was absolutely relevant. Some of the Sandia papers apparently included sections on situations where targets attempt evasive maneuvering while being lased. It all makes sense, but the inherent dual-use nature is explicitly cited why such projects have not advanced beyond theory. Quote Link to comment Share on other sites More sharing options...
AckSed Posted March 20 Share Posted March 20 Tests show high-temperature superconducting magnets are ready for fusion tl;dr New superconducting REBCO magnets tested that run at 20 Kelvin and made a steady field strength of 20 Tesla. Unique, no-insulation design that allows you to lower the voltage, which leaves more room for more cooling or stronger structures. Deliberately quenched a full-scale coil to see what broke and where the models failed, so they could update their models: one corner melted, most of the rest of the coil survived with no damage. Led to revisions in design that are supposed to prevent the failure mode. Quote Link to comment Share on other sites More sharing options...
AckSed Posted March 29 Share Posted March 29 Ever since the Industrial revolution, humans have been searching for more ways to boil water into steam for industrial processes. Coal boilers. Gas boilers. Concentrated solar. Nuclear reactors. Now someone is proposing heatpumps, which is more viable on industrial scale than you might think. And the government seems to agree, awarding them up to 145 million dollars to develop their drop-in heat-pump boilers to convert low-grade heat into industrial steam. The specs seem right, because at minimum, it uses water as a refrigerant, can work on heat sources as low as 29 deg. C and operate at a Coefficent of Performance of 2.1. It's even capable of leaving the gas boilers in place as a backup. Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted March 29 Share Posted March 29 (edited) 47 minutes ago, AckSed said: Ever since the Industrial revolution, humans have been searching for more ways to boil water into steam for industrial processes. Coal boilers. Gas boilers. Concentrated solar. Nuclear reactors. Now someone is proposing heatpumps, which is more viable on industrial scale than you might think. And the government seems to agree, awarding them up to 145 million dollars to develop their drop-in heat-pump boilers to convert low-grade heat into industrial steam. The specs seem right, because at minimum, it uses water as a refrigerant, can work on heat sources as low as 29 deg. C and operate at a Coefficent of Performance of 2.1. It's even capable of leaving the gas boilers in place as a backup. Yeah, I saw that. About time, really, that someone found a way to recover all the low-grade waste heat getting dumped into the environment. Although I admit, I was waterskiing near a thermal power plant and finding the warm water plume was quite nice, compared to the rest of the inlet. But I digress.... A while back I was wondering if this sort of tech could be used to concentrate the waste heat going to radiators in space vessels, like the ISS. Radiators can shed heat faster the hotter they are; while it would take some power to run the heat pumps, it would allow more heat to be dumped per unit area. Perhaps the waste heat could even be pumped up enough to generate some electricity. Not enough to run the pumps, I know, but at least recover some energy... Edited March 29 by StrandedonEarth proofreead before posting.... Quote Link to comment Share on other sites More sharing options...
magnemoe Posted March 29 Share Posted March 29 (edited) 4 hours ago, AckSed said: Ever since the Industrial revolution, humans have been searching for more ways to boil water into steam for industrial processes. Coal boilers. Gas boilers. Concentrated solar. Nuclear reactors. Now someone is proposing heatpumps, which is more viable on industrial scale than you might think. And the government seems to agree, awarding them up to 145 million dollars to develop their drop-in heat-pump boilers to convert low-grade heat into industrial steam. The specs seem right, because at minimum, it uses water as a refrigerant, can work on heat sources as low as 29 deg. C and operate at a Coefficent of Performance of 2.1. It's even capable of leaving the gas boilers in place as a backup. Heat pumps works great as in they electricity to convert an small temperature difference to an larger one. All the way to using the -10 centigrade outside air to produce hot air in your house. Assume the same is true here but used on industrial waste heat. Leaving the gas boilers in place could be smart as during winter you use the wast heat for heat stuff instead who is more efficient but this is wasted during summer. Edited March 29 by magnemoe Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted March 29 Share Posted March 29 Let's imagine a heatpump of the Universal size. The entropy is defeated, a perpetuum mobile is in every car. Quote Link to comment Share on other sites More sharing options...
darthgently Posted March 29 Share Posted March 29 3 hours ago, kerbiloid said: Let's imagine a heatpump of the Universal size. The entropy is defeated, a perpetuum mobile is in every car. Maxwell's Demon tamed Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted March 30 Share Posted March 30 Quote A heat pump is a device that uses work to transfer heat from a cool space to a warm space by transferring thermal energy using a refrigeration cycle, cooling the cool space and warming the warm space.[1] In cold weather, a heat pump can move heat from the cool outdoors to warm a house; the pump may also be designed to move heat from the house to the warmer outdoors in warm weather. As they transfer heat rather than generating heat, they are more energy-efficient than other ways of heating or cooling a home.[2] A gaseous refrigerant is compressed so its temperature rises. When operating as a heater in cold weather, the warmed gas flows to a heat exchanger in the indoor space where some of its thermal energy is transferred to that indoor space, causing the gas to condense to its liquid state. The liquified refrigerant flows to a heat exchanger in the outdoor space where the pressure falls, the liquid evaporates and the temperature of the gas falls. It is now colder than the temperature of the outdoor space being used as a heat source. It can again take up energy from the heat source, be compressed and repeat the cycle. So, when I was suggesting exactly that for cooling the Venereausian habitats with a turboexpander, powering it with an external nuke reactor, they were laughing "Ew! Ew! You dunno da Carnot cycle!" But when it has a brand label and called "heat pump", it is "Wow! Wow! Heat pump is da best!" A well-educated KSP player is so well-educated... Btw, the wiki doesn't explain the word "compressed". It is still compressed by the power of air and fire elementals power station. Quote Link to comment Share on other sites More sharing options...
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