[HN Gopher] We've spotted a planet surviving its dying star ___________________________________________________________________ We've spotted a planet surviving its dying star Author : gmays Score : 159 points Date : 2021-10-14 12:08 UTC (1 days ago) (HTM) web link (theconversation.com) (TXT) w3m dump (theconversation.com) | eesmith wrote: | Published at https://www.nature.com/articles/s41586-021-03869-6 . | "Dying" refers to "survive the volatile evolution of their host | stars into white dwarfs." | TMWNN wrote: | The classic short story "A Pail of Air" (1951; | <https://en.wikipedia.org/wiki/A_Pail_of_Air>) depicts human | survivors of a frozen Earth without the Sun. | denton-scratch wrote: | "Dying" is a bit of an under-statement. A white dwarf is to all | intents and purposes dead. It has no source of energy, and | radiates only because of stored heat. | | That heat dissipates so slowly that (AIUI) no white dwarf in the | universe has yet had time to cool down enough to stop radiating | (i.e. the universe does not yet contain any black dwarves). | | So a star that is in the process of collapsing into a white dwarf | could reasonably be said to be "dying". Once it's collapsed, it's | dead. | Voloskaya wrote: | "Dying" is not referring to the state of the star today, but to | the process of death: the planet survived while it's star was | dying, which is the interesting bit of the story. | denton-scratch wrote: | Agreed. | | To survive in orbit around a WD is not a remarkable | achievement - you just carry on orbiting forever (roughly). | Orbiting a red giant would be pretty interesting, though - | the RG has an indistinct surface, its diameter and luminosity | varies, and it emits a lot of material as wind. | | To survive in orbit around a neutron star would be another | thing again. Neutron stars have intense magnetic fields, and | spin rather quickly, resulting in a rotating field that is | wrapped around on itself. That in effect creates a particle | accelerator, driving electron flows (the electrons were all | expelled when the NS collapsed) with extreme energies. | | Short of hanging around near an exploding supernova, I can't | imagine a more hostile environment. | hinkley wrote: | Would the magnetic fields of a neutron star create a tidal | locking effect through eddy currents in the planet's core, | boosting it into a larger orbit and slowing the spin of the | star? Seems like a giant inside out induction motor. | | I wonder what the band of survival is, where the planet | doesn't get turned to Swiss cheese first. | denton-scratch wrote: | I have no idea what the neighbourhood of a neutron star | is like, nor what the effects of such intense fields | might be. This is theoretical physics and cosmology. I'm | not competent even to speculate. | | Yes, I get the "induction motor" idea. With fields and | voltages that intense, I guess just about anything | becomes conductive. | | [Edit] I don't know whether those field strengths are | consistent with atoms continuing to be atoms - I guess | there must be some range beyond which a thing like a | planet could maintain its integrity. But (guessing | wildly) I would expect there to be a region around a | neutron star within which it is impossible for atoms to | exist. | justshowpost wrote: | Newly discovered Click-Bayitt type stars | [deleted] | postalrat wrote: | Next you are going to say that a phone is dead unless it's | being charged. | denton-scratch wrote: | Please explain how a "charger" for a white dwarf might work! | I mean, you could just chuck a huge ball of hydrogen at it; | that might work, but it'd be easier to just bundle together | two balls of hydrogen and make a new star. | | I think I'd expect a charger to restore a phone to something | like its as-new functionality. I've never heard of any | mechanism that could change a white dwarf into not a white | dwarf, other than extreme age, or being merged with another | object. | rapsey wrote: | How would we see black dwarves? | Chris2048 wrote: | A BD is still hotter than background temp, so you could maybe | see faint IR, and you could initially find it as a result of | its mass if there are nearby objects orbiting (although now | less illuminated), or simply transitioning in front of other | stars (I guess that's how they find wandering planets?). | | Alternatively, map all the white dwarves, then wait long | enough, then look again.. | kadoban wrote: | You'd probably also be able to see white dwarves that were | on their way to being black (whatever the threshold is). | Chris2048 wrote: | Given there are no BDs (so they are theoretical) maybe | there isn't a threshold defined? | | A WD will slowly cool to a BD over Trillions of years, so | it's all linear. Funnily enough, they are probably every | shade of red/brown in-between - but "brown dwarves" are | usually reserved for objects that never where "proper" | hydrogen-fusing stars, but are large enough to fuse | deuterium. | kijin wrote: | There's no hard threshold, the star just fades gradually | from #FFF to #000. | | A fully black dwarf would be so cold it would be | indistinguishable from cosmic background radiation, but | that's going to take at least a trillion times longer | than the current age of the universe. Not just slightly | longer. | kadoban wrote: | Right. I'm just saying that if the are any black dwarfs | (which there should not be), we should be able to find | ~arbitrarily dim ones as well, down to our ability to | see. | dredmorbius wrote: | Gravitational lensing, most likely. | | Possibly through gravitational interactions with non-dwarf | stars in the same system. | | There not being any yet makes either method somewhat more | challenging. | Ericson2314 wrote: | If there were bright things behind them | | The universe is young, a lot of stuff hasn't happened yet. It | wouldn't be surprising if we are about the earliest life of | this sort that could exist. | vlovich123 wrote: | I thought the cosmological expansion theory of the standard | model was falling apart calling into question the Big Bang | theory. If that's the case, then are we sure we have a good | handle on the age of the universe? | garblegarble wrote: | Do you have any links where I can read more about that? | That's fascinating and I wasn't aware, and I evidently am | not using the right search terms to find out more | Taek wrote: | Maybe unrelated but YouTube has been throwing a lot of | faux science and astronomy at me lately. Youtubers | reading controversial papers presented as indisputable | even when there's no scientific consensus at all on the | results. | whatshisface wrote: | It's depressing to think about, but for many intents and | purposes fake space facts are just as good as true space | facts. | 6502nerdface wrote: | Especially for purposes of monetizing YouTube videos. | contravariant wrote: | Depends on your perspective I suppose. Most of the stars | have already formed and star formation will slowly grind to | a halt in a few billion years. | Ericson2314 wrote: | old and young universe then :) | | At least, I can understand visualize the time scale of | the universe a lot better than I can visual the length | scale. Speed of light doesn't feel like 1/1 to humans! | JohnJamesRambo wrote: | https://www.scientificamerican.com/article/living-near-a-whi... | | I've always found this idea neat. | Koshkin wrote: | An informative piece, thanks for sharing. (Being tidally | locked complicates the situation, I think.) | uyaij wrote: | > By damping trash onto the surface of the white dwarf, one | could harvest its gravitational binding energy from the | emitted electromagnetic radiation at nearly the yield of | nuclear fuel. | | This sounds interesting, how would such a method of power | generation work? | jerf wrote: | Well, that very nearly _is_ the method of power generation. | It would presumably be paired with some sort of Dyson | sphere around the white dwarf. (Remember that a "Dyson | sphere" isn't necessarily a solid shell, but just some | configuration of matter where no matter which direction the | energy goes it is intercepted by something.) | | You may also enjoy: https://www.youtube.com/watch?v=t-O- | Qdh7VvQ which is a minutephysics on black hole power using | much the same principles but attaining yet higher | efficiencies. | justshowpost wrote: | Sorry, but it has to be rigid to be a sphere. Angular | momentum is a bitch! | | PS: Dyson Spheres is misnomer, Olaf Stapledon should be | credited for this idea (Star Maker 1937) | FredPret wrote: | So we would decelerate the trash, it hits the white | dwarf, gets crushed, and then undergoes various nuclear | transformations resulting in energy output we would then | capture with our Dyson swarm? | m1n1 wrote: | Is "damping" a technical term, distinct from "dumping"? The | article uses it more than once so it seems deliberate... | orra wrote: | Damping is a physics or maths term. To damp means to | (steadily?) decrease the amplitude of a wave or | oscillation. | saltcured wrote: | Damping is generally a technique which reduces, slows, or | restricts a system. It is not a synonym for dumping. We | have old, related terms like the "damper" on a fireplace, | which I suspect may invoke a more basic analogy of | putting water on wood fuel, i.e. making it damp and | slower to burn. | | In modern usage, "damping" usually refers to a drag or | parasitic affect in some oscillatory system, but it does | not have to be oscillatory. It can be other drag effects | that convert energy, with a usual assumption that it will | bring the system to a new equilibrium. An object falling | through the atmosphere can be considered to have its fall | dampened by the air drag, converging towards its terminal | velocity. | | I am not familiar with all the physics involved in | falling towards/into such a star, so I do not know if | there are field effects which would cause damping of the | fall prior to impact of the trash with an actual surface, | similar to the atmospheric descent towards earth. I also | wonder if they imagine the orbital system is being damped | to allow the trash to impact the star, by bleeding off | tangential velocity to decay the orbit. | tamaharbor wrote: | I assume this would accelerate global warming. | justshowpost wrote: | Isn't that just a simple formula? I even seen planet | destroyed/remains on some of stellar evolution simulators. | | It all depends on orbit radius and star mass at the end of | Asymptotic Red Giant Branch. | | Note that white dwarves aren't stars but rather _stellar | remnants_ without energy source. | yummybear wrote: | If you write an article with "we spotted", then please provide | some image material, even if only a graph. | purplecats wrote: | It seems to be the cool thing to do lately. Especially if you | have a visual web app, a tool that has a functional GUI | component, or a breaking story about the planet or a new piece | of hardware, you must make sure not to include the one thing | that would make it most worthwhile -- a picture. | [deleted] | reedf1 wrote: | You'd probably be disappointed. The best you could hope for is | a graph of luminous flux vs time, showing the slightest | decrease as the planet transits some emission nebulae. | [deleted] | nsonha wrote: | Astronomy "images" are computer generated anyway, often with | artistic touches. | zhte415 wrote: | While I'm no astrophysiyst I don't think it's a matter of | 'their sun was there last week, look, this week it's not' and | nor do I think an artist's impression of something orbiting | nothing adds any more, nay, indeed adds nothing, to the written | description. | wongarsu wrote: | The paper contains figures like [1] or [2], which I think do | add something to the written description (and obviously the | paper authors thought so too, otherwise they wouldn't have | included it in the paper). These visuals are quite useful | when talking about what we mean by "spotted" (though the | context is important and the article only spends maybe two | paragraphs on the actual observation method, so there's some | danger of misinterpretation) | | 1: https://www.nature.com/articles/s41586-021-03869-6/figures | /1... | | 2: | https://www.nature.com/articles/s41586-021-03869-6/figures/7 | simonh wrote: | Those images would be copyrighted, so may not be available | to the publisher of the article. | sigg3 wrote: | Where are all the graphical artists at? | | We had an Ask HN here, like yesterday. | wongarsu wrote: | I'm sure the authors and their institutions would be | happy to grant the right to use the images in an article | about the paper if somebody asked them. Publicity for the | finding is in their best interest. Unless their | publishing agreement with Nature restricts this, not sure | how strict exclusivity is in those cases | simonh wrote: | In some cases, for some papers it might be possible to | eventually get rights to the charts that would satisfy | your own publisher's legal department yes. They'd have to | jump through those hoops every time though, and time is | money. | ziddoap wrote: | Perhaps I missed it, but I'm curious to how they know this is a | planet which survived the red giant phase vs. a planet which was | captured afterwards (or formed from the debris caused from the | star -> red giant -> white dwarf transition). Maybe it's covered | more in actual paper. | platz wrote: | But, who wants to live forever? | shadykiller wrote: | Why would the planet be destroyed or have it's course altered ? | The Star's mass remains the same and so does the gravity. | Wouldn't the planet's own gravity hold it up when it's engulfed, | and retrain shape when the star becomes a white dwarf ? | joe-collins wrote: | Well, there would be some extra drag, for one. | MauranKilom wrote: | > The Star's mass remains the same | | What makes you think so? I'm no expert, but matter is | definitely expelled in the process of forming a white dwarf. | The stuff scouring the inner planets doesn't appear out of thin | air... | | This random paper also appears to say that the mass lost is on | the order of half the initial mass: | | https://iopscience.iop.org/article/10.3847/1538-4357/aadfd6/... | | > total stellar mass loss ranges from 33% of M_initial at 0.83 | M_sun to 83% of M_initial at 7.5 M_sun. | FredPret wrote: | Not an astrophysicist, but it might get torched, blown away by | the initial shockwave, or maybe drag between the planet and the | solar atmosphere will slow its orbit into a collision course. | tlholaday wrote: | Sol is gas, right? | | Gasses cool when they expand, right? | | What's the expected surface temperature of Sol after it has | expanded past Earth's orbit? | gs17 wrote: | Looks like it will drop to about half the current surface | temperature as it expands (although this seems to be talking | about it at around 0.5 AU) http://www.astronomy.ohio- | state.edu/~ryden/ast162_4/notes15.... | tlholaday wrote: | Thanks for the link. I wonder what temperature prevails at | 1.0 AU. | | On the one hand, artists' conceptions of boiled oceans and | cities in cinders that saddened and discouraged me in my | childhood. On the other hand, the heat energy density of Sol | today is comparable to a compost heap. When the radius of a | sphere doubles, it's volume increase eight times. | | If Sol is too itsy to start helium fusion, maybe orbiting | within the post-expansion photosphere - the hydrogen envelope | - is chill, damp, and sparky? | rootusrootus wrote: | The sun won't (potentially) swallow up the Earth for about | 8 billion more years. The carbon cycle on this planet will | have ended about 7 billion years before then; the increased | output of the sun will have boiled away the oceans; plate | tectonics will stop, etc. There won't be anything alive on | this planet left to see the sun burn out. | edge17 wrote: | Out of curiosity, the video part way down ("White Drwarf System | Animation Text") showing the dying star... how are these videos | created? Is it done in something like Blender? The video credits | Keck Observatory, do they have 3d artists on staff for this kind | of thing? Do Astronomy grad students just learn how to create | visualizations? What's the turnaround for getting something like | this made because I'm assuming it was made for the press release. | Gauntleteer wrote: | I work for the Keck Observatory (engineer). Far as I know we do | not have any 3D animators on staff. We produce images from our | science instruments for the astronomers to download and they | all eventually end up here: | https://www2.keck.hawaii.edu/koa/public/koa.php | t789623239782 wrote: | The first extrasolar planets discovered had survived a supernova | explosion: https://en.wikipedia.org/wiki/PSR_B1257%2B12 ___________________________________________________________________ (page generated 2021-10-15 23:01 UTC)