Dying Star or Beautiful Bird?

Article written: 12 Jul , 2010
Updated: 24 Dec , 2015
by

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What a gorgeous new Hubble image! At first glance this object looks like a beautiful, giant, translucent bird. But it is actually star shedding its outer atmosphere. The cloud around this bright star is called IRAS 19475+3119. It lies in the constellation of Cygnus (the Swan) about 15, 000 light-years from Earth in the plane of our Milky Way galaxy.

From the ESA Hubble website:

As stars similar to the Sun age they swell into red giant stars and when this phase ends they start to shed their atmospheres into space. The surroundings become rich in dust and the star is still relatively cool. At this point the cloud shines by reflecting the brilliant light of the central star and the warm dust gives off lots of infrared radiation. It was this infrared radiation that was detected by the IRAS satellite in 1983 and brought the object to the attention of astronomers. Jets from the star may create strange hollow lobes, and in the case of IRAS 19475+3119 two such features appear at different angles. These curious objects are rare and short-lived.

As the star continues to shed material the hotter core is gradually revealed. The intense ultraviolet radiation causes the surrounding gas to glow brilliantly and a planetary nebula is born. The objects that come before planetary nebulae, such as IRAS 19475+3119, are known as preplanetary nebulae, or protoplanetary nebulae. They have nothing to do with planets — the name planetary nebula arose as they looked rather like the outer planets Uranus and Neptune when seen through small telescopes.

This image was created from images taken using the High Resolution Channel of the Hubble Space Telescope’s Advanced Camera for Surveys. The red light was captured through a filter letting through yellow and red light (F606W) and the blue was recorded through a standard blue filter (F435W). The green layer of the image was created by combining the blue and red images. The total exposure times were 24 s and 245 s for red and blue respectively. The field of view is about twenty arcseconds across.

Source: ESA Hubble


41 Responses

  1. Member
    Aqua says

    Talk about your asymmetric explosion! Definitely a fascinating image…

  2. Hon. Salacious B. Crumb says

    Aqua calls this a “asymmetric explosion.”

    No. It is not pre-planetary nebula, and planetary nebula are a consequence of high velocity superwinds, producing the observed shapes of the observed nebula. This nebula is illuminated by ultra-violet light emitted by the dying star or the exposed hot white dwarf. There is no explosive event during this phase of stellar evolution.

    Aqua this same point has been mentioned before. Please stop saying this in an “explosion” of some sort as this is absolutely wrong.

  3. astrofizix says

    With all due respect Crumb, although you are absolutely correct in saying that it is indeed not an explosion, don’t be too harsh to correct someone when they are just complimenting the imagery.

    It is my understanding that although it is not an “explosion” in the classical sense, we are not really sure what actually triggers the final phases of the giant branch (except for the helium flash in the asymptotic giant), whether it be deflagration or detonation. Modeling the large scale fluid dynamics of a supernovae is a very delicate field. Definitely an unsolved combustion problem.

  4. Lawrence B. Crowell says

    The swollen red giant does go through episodes of blowing off gas. If you were up close these would be explosions of sorts, similar to solar flairs magnified by 10,000 or so. On the other hand this is a very mild process compared to a supernova.

    LC

  5. Hon. Salacious B. Crumb says

    Actually, there cannot be an explosion of any sorts as there is no mechanism to some kind of outburst. I.e Unlike the novae (but these are not caused by mass loss from AGB stars)
    The star, as in this case, has swollen to a large star, with the winds caused by the tenuous outer atmosphere to be blown away by the core of the stars.
    The shape of the nebulosity is controlled probably by the magnetic field from the star, and the mass loss is likely slightly more prominent from the equatorial regions via starspots and at the poles.
    This article is correct saying “…phase ends they start to shed their atmospheres into space.
    I still do understand how people hold onto this old notion, which has been out of vogue at least since the 1960s. If you have doubt of this I could several dozen reference without any hesitation. A good one is; Ortiz, R., et.al.
    Evolution from AGB to planetary nebula in the MSX survey. A&A., 431, 565 (2004)(arxiv on-line one given.) – especially the iIntroduction. [There are no explosion mentioned in this article!]

    The well studied object’s name, by the way is PM 2-42, however, as it is a post-AGB Star (proto planetary nebulae) it does not have a PN G or PK number. Also, it should be said the central star is HD 331919 V2324 Cyg and is a 9.5v magnitude star with the supergiant spectral class of F3Ib. It is the mass of this star that has caused the massive bipolar outflow that we observe, and it has a dusty optically thick circumstellar disk or torus around the star. It has large grains within the observed torus.

  6. Excalibur says

    Astrofizix:

    “…It is my understanding that although it is not an “explosion” in the classical sense, we are not really sure what actually triggers the final phases of the giant branch (except for the helium flash in the asymptotic giant), whether it be deflagration or detonation. Modeling the large scale fluid dynamics of a supernovae is a very delicate field. Definitely an unsolved combustion problem”

    Huh? Supernova, deflagration, detonation about an article about a planetary nebula?

  7. undifined says

    looks like a romulan warbird to me 😉

  8. Hon. Salacious B. Crumb says

    Astrofizix said; “…we are not really sure what actually triggers the final phases of the giant branch.

    This comment for me is a bit mysterious. Simply what triggers the final phases is the moving towards halting of all the thermonuclear reactions in the core. Here the core shrinks is size as the energies pushing against gravity decrease. This increases the temperature, which in turn drives the rate of the mass loss of the hugely expanded outer atmosphere. These changes are not constant and nor are the constant in the chemical composition of the final superwind.

    Again you seem to have you mind fixed on some large energy event happening inside the star causing an ejecta event – like the novae or supernovae. In ordinary stellar-like circumstances this does not happen.

    As for the helium flash occurs inside the star, but it is not an explosive event. This flash generates lots of energy, making the star seem born again and visible bluer. However this happens only for a short time, when the again just settles down with the power down phase. (it might be repeated a coupe of times, via so-called dredging-up but the energies made are much less than previous one.) The Helium flash also happens as the very end of the AGB phase.

    Also during this time, the material outflows are described as ordinary winds. When they reach the end of the AGB, the outflow becomes a superwind – which is where this object roughly lies right now. The nebula where the star is still in the AGB phase shines mostly by reflection, but in the pre or proto planetary nebula starts to shine by fluoresce – thus beginning to illuminate the planetary nebula shell.

    To say this process is “Definitely an unsolved combustion problem” is not very accurate. We understand the basics, all we now need to do in to refine how the process works by scale and by energy production.

    Note: If the progenitor star is above about 2.25 solar masses, it is likely there are two ordinary wind and superwind phases

  9. Aodhhan says

    Since an “explosion” is basically just a sudden release of a great amount of pressure, I would say there are a many explosions going on. It also means there are many types. An explosion, doesn’t necessarily destroy something.

    Don’t mind dumb crumb. If he decides something is right, then it is… even when the rest of the world knows better.

    He’s another one who cuts and pastes. What is really funny, is when he doesn’t realize when someone else makes the same comment, only much more readable to the public.
    A dead give-a-way for someone who only wants conflict, so he’ll do some half-arse research and suddenly believe he’s an expert.

  10. Hon. Salacious B. Crumb says

    Another typical ill informed comment by Aodhhan. He, yet again, bitterly complains about everyone but as usual does not say anything about the subject at hand. The only “explosion” here is going inside his own head!

  11. Lawrence B. Crowell says

    This debate over explosions is really a matter of scale. This star is not an exploding star, that fact is clear. This star is entering it final stage, and it has evolved to a point where it can no longer sustain fusion.

    The equation for hydrostatic equilibrium of a star is a pressure form of Newton’s law of gravity,

    dP = -GM rho(r)dr/r^2.

    Here M is the total mass of the star and rho(r) is the density of material in a shell spherically symmetric about the center at r to r + dr. This would not be a hard equation to manage if the density was constant, such as with a fluid, but the star is composed of gas where the density varies with radius. Also the density as it varies with radius can depend upon the temperature of the material in that radius. So now we have to include thermodynamics. The problem has become complicated, but the second law of thermodynamics tells us the free energy stocks in the star will be consumed, and this will change the configuration for hydrostatic evolution.

    There are astrophysicists who run this problem in an iterated algorithm. The upshot is that the fusion starts out in the core, but the hydrogen is consumed and replaced by helium — sometimes called helium ash. The hydrogen burning begins to take place on a shell around the core, and the density configuration of the star adjusts as the core contracts to increase the gravitational pressure on the burning shell. Over time the burning shell migrates outwards as the helium core increases in mass, and contracts further. However, eventually this process runs out of the matter radially outside the burning shell to sustain the fusion, as this matter will expand more and more will less gravitational force to counter the outwards pressure due to heat. This is where the star swells up. If the star is massive enough the helium core may initiate fusion to produce heavier elements, but this is a complicated process.

    Of course as the star swells up hydrogen gas is thrown off, generating a sort of stellar wind. This luminous cocoon is the result. Yet the process is clearly not a steady state process. The webbing or filigree in cloud, such as in the Cat’s Eye Nebula, does indicate this happens with pulses and episodes of considerable flaring off of gas. It is interesting to me how this does happen with a high level of symmetry to generate these very symmetric gas shells. The structure of these does indicate the gas shell is not produced by a constant wind, but by pulses of out gassing — which might be considered explosive. At least if you were up close and personal it might appear pretty violent.

    LC

  12. Jon Hanford says

    While looking for some info on the low luminosity halo seen in the image (overlaid on the two bipolar nebulae) I came across this 2007 HST study of IRAS 19475+3119: http://iopscience.iop.org/0004-637X/658/1/410/pdf/70323.web.pdf

    Besides containing some amazing imaging of this object, a fairly non-technical (i.e. no math) description of the structure and formation of this rare quadrupolar PPN is given in Sec. 8. They find that the main sequence progenitor of this PPN likely had a mass >2.5 solar masses and the bipolar lobes are about ~2000 years old. Optical spectroscopy and millimeter-wave observations (looking at kinematics and dust properties) are also presented.

  13. Torbjorn Larsson OM says

    To discuss explosions we need a suitable definition that abstracts away from chemical explosions. Wikipedia supplies “increase in volume and release of energy” and “creates a shock wave” which is physically intuitive; thus an impactor isn’t an explosion in the impacted body (energy & shock wave, but lacks volume increase).

    Planetary nebula can have all of these AFAIU, but presumably don’t need to have shock waves?! Then IMHO we seem to land somewhere in the neighborhood of LBC characterization – if you accept Wikipedia’s definition it depends on what you feel close up and personal (may be localized regions of shock waves)!

  14. Lawrence B. Crowell says

    Jon,

    Thanks for the paper. From an astrophysical perspective this is a babe in arms.

    LC

  15. Aodhhan says

    Crumb…
    I have nothing to say the article didn’t already go over. Unlike you, I don’t pretend to be an expert at EVERYTHING.

    Aqua’s comment about an explosion, wasn’t in the context meaning it was being destroyed by it. However, since you probably couldn’t find a reference to explain what he meant… you decided to jump all over him.

    All he did was make an observational (perhaps metaphorical) comment, not one of expertise. Certainly not one which deserved your criticism. At least he doesn’t have to use the words of others.

    Perhaps if you read the uncommented parts of LBC’s post, you might just understand things a bit more.

    In the most basic, scientific 101 dictionary, in this context an “explosion” is a violent release of energy (from state, not size)caused by a chemical or nuclear reaction. You could also see it being a rapid increase in volume and release of energy in an extreme manner.
    It is also what happens just about anytime you post… you cause and explosion of snickers and laughter.

    So if you really want to get technical, you are wrong and Aqua is correct. Just another example where you think you understand the definiton, but either you do not, or you misunderstand its context.
    Apparently this isn’t limited to scientific nomenclature… you have problems with uncomplicated meanings as well.

  16. Aodhhan says

    Crumb…
    and before you say anything about me getting on you.
    I only get on two people here. Both who try so unsuccessfully to make people believe they know everything about the Cosmos and are never wrong.
    Yet you and the other idiot seem to belittle anyone; especially if you somehow think you are superior to them. Although, it is clearly out of ignorance.

  17. Hon. Salacious B. Crumb says

    zzzzzzzzzzzzzzz….

  18. Member
    Aqua says

    oTay… I will amend my comment. How about – slow motion explosion? Definitely there is an eruptive event in progress. Nit picking over whether or not it is an ‘explosion’ seems rather…. hard pressed to make a point. Nit nit nit… Can we agree that this observed prominence is at least asymmetric?

    I see the event as the result of a rotating core with episodic eruptions as if when the poles of said object reach a confluence with either the galactic mag. field and are rendered radiative due to field enhancement or when a conjunction of bipolar or quadripolar electrogravitational emphasis becomes dominant in the ongoing fusion processes.

  19. Hon. Salacious B. Crumb says

    @ Aodhhan
    The only person I am superior to is you.
    Yet only a total idiot would argue that planetary nebulae are related to some form of explosion.
    If you had any idea of the topic you would realise that supernova and novae are unrelated to planetary nebulae. The problem is that it does not differentiating between the appearance of the gaseous shells around these objects. It is a common and wrong misconception and is generate by ignorant people who should know better.
    After read this latest tirade, one think is clear you happily criticise other but hide you ignorance by saying nothing.
    Frankly, based on historical evidence, I think your just upset because other know more than you!!
    Let’s see. You have accuse me before of “cut and pasting.” OK, where did I take it from then? If you can’t prove that here, therefore show us. If you can’t, then that it proves your a lowlife liar. So C’mon, put up or shut up!

  20. TerryG says

    Can we agree that this observed prominence is at least asymmetric?

    It is apparent that some contributors aren’t going to agree on the color of an Orange (Nit Nit Nit), but noting that many snowflakes have six-fold symmetry under rotation, you could also look down the axis of rotation of this object, recognise an approximate cruciform shape and say there is a rough two fold or four fold symmetry (Yip Yip Yip).

  21. Hon. Salacious B. Crumb says

    @Aqua

    I sorry if I seemed a little harsh. The problem is that stating there is explosive is a message that can easily be confused by novices.

    Teaching astronomy and stellar evolution classes for many years has found this very issue is often very confused to some. Most look at all planetary nebulae and their mimics by seemingly intuitively is caused by a some huge single outburst – and look at as some supernova or nova event. (Both these events are, of course, unrelated.)

    The visible shells and features are mostly visible from the light central star, and we know this because we see fluorescence lines in the nebulosity’s own spectra like [OIII], etc. The apparent shock front is caused by the boundary between the slow ordinary wind (at 10 km/s) and the higher velocity hot superwind that is moving at 1000 km/s. [Eventually the expanding shock front produces the bubble-like features – and is the theory known as a snow plough model. It is a bit more complicated than this though.]

  22. Lawrence B. Crowell says

    Aqua: A supernova is an entirely different process than a nova. In fact there are different supernova types as well. A nova is really a very gentle puffing off of the exterior layers of a bloating up red giant as the final phase of a main sequence star. I think the problem is the use of the word explosion. In one sense a solar coronal flare or emission is an explosion, a hell of a lot more powerful than any multi-megaton hydrogen bomb we make. In the case of a nova these stellar flares are a whole lot bigger. This is in contrast with a supernova, where for a single star it is a huge fusion induced shock wave catalyzed by a violent core implosion. For SNIs it is the violent implosion of a white dwarf into a sort of fusion bomb, on a stellar mass scale, which fuses around a solar mass of light elements rapidly — BOOM. We can see these across billions of light years. This nova cocoon has been developing over 2000 years, a short time by astrophysical standards, and a nova can persist for a few million years — somebody might want to check to see if my memory is right. A supernova explosion lasts a few weeks, and peaks at the start in a few hours. These are really serious stellar bombs.

    As for the kafuffle between Hon. Salacious B. Crumb and Aodhhan, this particular matter is a bit of a quibble, but it does point to a problem. Aodhhan said in a post above “Yet you and the other idiot seem to belittle anyone …,” and referred to “Dumb Crumb.” The problem is that Aodhhan approaches things in a generally combative and insulting manner. He appeared on this blog last December by launching a barrage of insulting comments against me. I generally try to ignore them, while SBC takes this problem head on and counter attacks. On balance the source of these problems is Aodhhan.

    LC

  23. Excalibur says

    @LC

    “A nova is really a very gentle puffing off of the exterior layers of a bloating up red giant as the final phase of a main sequence star”

    No its not. A nova is an explosive thermonuclear event on the surface of a _white dwarf_ (not a red supergiant) and very much violent. What you describe above would be the a good explanation of the start of a planetary nebula though, but that is not a nova-event.

    The difference between a nova and a supernova is that the nova event is a surface effect and potentially repeatable, whereas the supernova involves the whole star (whether it be complete evaporation, or collapse)

    As for planetary nebula, i always refer to them as eruptive events, that brings away the potentially ‘dynamite action’ but still signifies a quite violent and disruptive event.

  24. exodus says

    okay people. I am definately no scientist. And wont even pretend to be. All I have and the only reason I come back to universe today is for my love and interest in the cosmos and humanitys advances trying to explore and understand it.

    Now in an effort to try to seem awfully intelligent, some of you find it necessary to belittle someone for making a comment as casual as ‘talk about an asymetric explosion!’

    come on! Your bickering is pathetic! Do you have any idea how incredibly immature you all sound? The article was about a new stunning hubble image. How in the world did that end up in a childish heated debate about the definition of the word ‘explosion’ masked by petty insults, big words and complicated formulas.

    Wake up! Call an apple an apple! This is a stunning image! Why irritate everyone with nitty gritty bull. Just enjoy the image! Celebrate it!

    You are making something beautiful unpleasant for the people who just want to admire the images and learn something new. If you already know something that others dont about a discussed topic. Share it! Dont gun down someone for incorrect word use. I can promise you most people dont take things up as litterally as you do.

    Keep in mind that by trying to make yourself look superior you make less knowledgable people like me to scared to comment or ask question. Which just isnt the scientific way. Steven hawking cant even communicate without the use of a computer and here you are blabbing about word definitions. If thats what people wanted they would go to dictionary.com not universe today.

  25. Aodhhan says

    Crumb…
    You bring up nova, planetary nebula, etc. I never made any comparison. Apparently you have a mental condition; something along the lines of schitzophrenia. Probably gives you an obvious inferiority complex…which explains why you lash out at people for no real good reason. I was talking about the definition of explosion… you twit.

    What is really funny is you prove my point again. Wherever you do not cut and paste, you use the word “THAT” far too much, and never use $50 dollar words.
    However, whenever you attempt to be intelligent (i.e you cut and paste others work) this word vanishes and a lot of $50 dollar words come out.
    When you attempt to hide this, it even becomes easier, because the words lose context and are incorrectly used.

    You’re busted and the true idiot. One so low, you could swing your legs off toilet paper. Now… shut up. I’m sure we will at least get a repreave on the use of “THAT” by you. LOL

  26. Aodhhan says

    LBC…
    You’re the other one who cuts and pastes others work. However, I can tell at least you learn something… so I will give you credit there.
    If you were truly so knowledgeable, Albert Einstein would be in awe. So give it a break.

  27. Lawrence B. Crowell says

    Excalibur: You are partially right, or more right than wrong. There are several types of nova, where what you describe is the fast type of nova. A slow nova (very slow) is more what I had in mind, where the star may increase its luminosity over a long time period. These are also associated with planetary nebula. What might be called the standard nova is a fusion burst due to the accumulation of hydrogen on the surface of a white dwarf star, as you indicate. The type of nova you describe increases in luminosity pretty quickly, while the slow nova associated with a planetary nebula has a slow luminosity period of increase and decrease. Stellar astrophysics is complicated, and what you learn in an undergraduate course a decade or two ago can turn out to be archaic.

    Aodhhan: I do not cut and paste. Most of what I write is from what I know. In fact most of what I write is fairly generic if you are seriously educated in physics. I don’t go to wiki-sites and copy up stuff to paste here.

    LC

  28. Excalibur says

    @LC

    I dont like the term nova for that phase because it clashes with a classical nova, especially in a laymans-oriented description of how a planetary nebula starts. It signals a violence in operation that does not reflect the true nature, wich is still violent just not as much.

    The buildup/expell process of the planetary nebula is a rather slow process (in human timeframe), that then suddenly lights up very quickly as the central star get exposed in sufficient detail.

  29. Lawrence B. Crowell says

    Maybe you re right. I am not sure of the history. It is my understanding that the white dwarf fusion source for a nova was figured out in the mid 1980s, while the red giant flare up was the older theory. However, you are correct in stating that most novas are due to a flash fusion event on white dwarf stars.

    LC

  30. Hon. Salacious B. Crumb says

    @ Aodhhan
    Glad to see your usual ridiculous tirade targeting the person rather than the subject. This kind of behaviour you would expect from a child not from an adult in a blog site.
    Sadly making wild and crazy accusations about someone you know little about just to make you feel good is an issue you will probably have to address – but unfortunately I do not have the skills to help you. The best example is your continued statements (across many Universe Today stories) accusing others of things that you have no proof or evidence for. I.e. This silly ‘cut and paste’ nonsense.
    The central point here is you are just making wild statements and personal attacks, and nothing related to subject. Regardless, of the irrelevances, it is clear the phenomena is not related any forms of some “explosion.” If you can’t understand that, it is not my problem. As you are unable or incapable of presenting a logical or factual reply, we can only assume that you don’t know very little about the story here or about the phenomena. If you want to contribute do so, but please stop acting as this way because it only makes you look more stupid.

    In the end all I feel is pity for you – and that is that.

  31. Aodhhan says

    Crumb…
    Trust me… I know all about the life cycle of stars. Most of the areas which are still considered theory I agree with… some I haven’t totally bought in on.

    Once again, you miss the point; it’s obvious you never will get it. Probably why you need to cut and paste the work of others.
    However, I am glad to see you started to remove the word “THAT” from your writing… as I predicted.
    ……maybe there is hope.

  32. Hon. Salacious B. Crumb says

    @Aodhhan
    You know nothing. That is why you rack off like the stinking coward when the going gets tough. From what little you have said here, and most of it is wrong, just proves the same point.
    I’ll happily bury jackasses like you any day.

  33. Excalibur says

    @LC

    Quoted from Wikipedia http://en.wikipedia.org/wiki/Nova

    NA: Fast novae, with a rapid brightness increase, followed by a brightness decline of 3 magnitudes — to circa 1/16 brightness — within 100 days.
    NB: Slow novae, with a 3 magnitudes decline in 150 days or more.
    NC: Very slow novae, staying at maximum light for a decade or more, fading very slowly. It is possible that NC type novae are objects differing physically very much from normal novae, for example planetary nebulae in formation. Exhibiting Wolf-Rayet star like features.
    NR: Recurrent novae, novae with more than one known explosion in historical times[8]

    So actually you are also correct, “Very slow novae” might be related to the episodic burst expelling gas from the central star into the “soon to be” planetary nebula. It doesnt change my view on the singular term Nova though, but in conjunction with “very slow” it does have a meaning.

  34. Lawrence B. Crowell says

    Excalibur,

    A question occurred to me which intrigues me. The white dwarf nova accumulates mass, mostly hydrogen gas, from its companion. The pressure builds up in the gas on the surface of the white dwarf and fusion takes place. This we detect as the nova. Of course the accretion of material then continues, but now the white dwarf has increased its mass by some “delta m.” So now the process repeats and there is a succession of these nova events as the white dwarf star approaches the Chandresekhar limit. So if we could watch this process long enough there would be a succession: pop, pop, pop, …, pop, BOOM! Where the pops are nova events and the BOOM is the SNI.

    This leads into the UT blog entry adjacent to this entry on detecting the precursors for SNIs. As the white dwarf accumulates mass the pressure on the shell of hydrogen gas, with some thickness dr on surface

    dP = GMrho(r)dr/r^2

    will change as the total mass with each cycle grows by M + delta m. So this might have two measurable effects. The first is that for some equation of state of hydrogen at the fusion point (which I don’t know) the energy released may change. The second is the periodicity of nova events leading up the SNI may also change, I suspect the period between nova events shortens. So the question is whether there are detectable aspects to nova events which might be signatures of a future SNI.

    Hon. Salacious B. Crumb

    Wow, if you keep it up you might be able to broom him out of here as you did with Anaconda & co.:-) Aodhhan is a form of a troll IMO. These people attract attention by causing controversy. In this case Aodhhan does so by launching salvos of insults against people. I think such people have caused those around them to detest them so much they have to go online to carry on with a life of snarkiness.

    LC

  35. Excalibur says

    @LC

    I dont know the answer to your question, but so seems nobody else (yet). I have read about ongoing investigations to the key question here: Does the nova event expell more mass than it accumulates inbetween explosions, or does it expell less.

    Looks to me a delicately tuned equation, and those are sensitive to small changes, so it might go either way. My gut feeling is that many (if not all) Nova originate this way.

    I have to agree that the pop pop pop pop BOOM scenario seems very likely, but probably with more random timings. To many variable factors, accretion disk variabilities, accretionspot variations etc. A slower accretion rate also seems to allow for much larger buildup with not so much larger nova flash, so it might even be that those that are repeating will stifle themselves, and it is the silent ones that are the worst (heard that one before).

  36. Excalibur says

    Replace Nova with SN-1a

  37. Lawrence B. Crowell says

    There are complicated issues here. If the white dwarf actually spalls off more mass than it takes in with each nova, then the white dwarf star can’t reach the Chandresekhar limit. I suppose what is most important is whether there is some scaling to the absolute luminosity of nova events as the mass of the white dwarf approaches the Chandresekhar limit. This might depend on details of the equation of state of hot hydrogen under these temperatures and pressures.

    To be honest I am no expert on these matters. it would require a bit of background research to even set up this sort of problem.

    LC

  38. Jon Hanford says

    @LC

    I came across an older (1987) paper ( http://www.springerlink.com/content/r77533p32u3374h4/fulltext.pdf ) that looked at white dwarf models for Type Ia and Ib supernovae and cataclysmic variables(Yeah, that’s the title). Several pre-supernova models are examined. While I’m not able to fully follow arguments presented, symbiotic variable and WD binaries(relatively high accretion rates) may be favored over cataclysmic variables and novae (w-relatively low accretion rates). There ARE a lot of things to consider. 😀

  39. Lawrence B. Crowell says

    Jon,

    These two are talking almost exactly what came to my mind. They discuss equations of state, but they don’t develop things much along those lines.

    Thanks LC

  40. lomitus says

    Isn’t it absolutely amazing that when someone makes a “nice comment about a pretty picture” that a bunch of bloated anally retentive pinheads feel the need to tear it apart and turn it in to a major issue of debate based on some utterly useless scientific theoryies quoting fomulas, science papers and variables and all that other crap because they’ve simply forgotten themselves how to simply look at and enjoy “something pretty”. Some of the people here are so utterly full of themselves that they’ve apparently lost the simple joy of appreciating something as beautiful as this image…explosion or otherwise. Sad and pathetic if you ask me. What’s the point in exploring the wonders of the universe and learning to understand it if you can’t take a few moments to enjoy it’s beauty…or if you feel the need to trash someone who can appreciate it?

    Honestly this whole debate some of you folks are blathering on and on about is no different than someone who looks at a rainbow and can’t see or apprecaite the simple beauty through all the damn mathmatics and equations…what utterly sad and depressing lives you must lead.

    Ultimately I have to agree with undefined…it does look like a Romulan Warbird 🙂

  41. Excalibur says

    Iomitus, maybe you are on the wrong forum… !? The forums for drawing pretty pictures is somewhere else…

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