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Icy(?) Comet Survives Pasage thru Solar Corona

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  1. Dec 17, 2011 #1

    Dotini

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    http://science.nasa.gov/media/medialibrary/2011/12/16/lovejoy_c3_anim2.gif [Broken]

    http://spaceweather.com/ <--- archive December 17, 2011

    In a rare curiosity of nature, Comet Lovejoy appears to transit the elevated temperatures of the solar corona, laughing off the sizzling encounter, seemingly even with a portion of its tail intact. Presumably it will have gotten a nice acceleration to wherever it is going next from its slingshot maneuver around our sun.

    Respectfully submitted,
    Steve
     
    Last edited by a moderator: May 5, 2017
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  3. Dec 17, 2011 #2

    Dotini

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    Last edited: Dec 17, 2011
  4. Dec 18, 2011 #3

    Drakkith

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    That's cool! I remember looking this up a few days ago thinking it was going to be a goner!
     
  5. Dec 18, 2011 #4

    Dotini

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    Re: Icy(?) Comet Survives Passage thru Solar Corona

    :cool:
    A passage from a Navy.mil blog:

    1700UT: I'm going to hope he doesn't mind me doing this, and steal a quote here from highly-respected astronomer John Bortle: "I trust that most here appreciate that we are witnessing one of the most extraordinary events in cometary history."

    Let that sink in a minute, because he is absolutely correct. This is not simply "news-worthy", or even "of great interest"; this is indeed completely extraordinary.

    Sungrazing comets, particularly those of the Kreutz-group, have fascinated astronomers for decades, and no doubt terrified civilizations of the past, as their orbits hurled them through the solar atmosphere, resulting in a brilliant daytime illumination of these enormous 'dirty snowballs'. There is arguably no other object in the solar system that goes through such an intense experience as one of these comets. For days now we have been witness to such a beautiful object racing through the STEREO, SOHO and now SDO and PROBA images, blasting through the solar corona, and miraculously re-emerging, albeit with much less of a tail than it started with. And whereas sungrazers of the past have been lost at least temporarily, if not permanently, in the Sun's glare, thanks to an amazing fleet of sun-watching spacecraft we have now been enthralled by this entire passage without a single hour passing by unwitnessed. Purely for the spectacle of the event, and the way it has unfolded before our eyes over the internet, this comet has sealed its place in the history books.

    But there is so much more to this than just the spectacle. We have already obtained unprecedented scientific data from five different spacecraft, and I'm very optimistic that over the coming days we will get to add a sixth spacecraft to that list when Hinode analyze their data. The result is an almost overwhelming catalog of visual, narrow-band filtered, extreme ultraviolet, and spectroscopic data of a comet experiencing the most extreme environment the solar system has to offer. We will likely learn about its mass, its physical size, its composition, the size of its dust and dust production rates, and so much more. Objects like this can also provide us with a tremendous amount of information about the solar wind and conditions in the solar corona, which in turn allows us to gain more understanding of the Sun as a driver of "Space Weather" at Earth (it's one of the reasons my group is interested in sungrazing comets).

    So I could not agree more with John, and I hope that all of you who are watching these movies are indeed appreciative of just how incredible this has been!

    http://sungrazer.nrl.navy.mil/index.php?p=news/birthday_comet [Broken]

    http://sungrazer.nrl.navy.mil/index.php?p=images/lovejoy/EUVI_B_lovejoy.gif [Broken]
    A brief clip of the tail wiggling within the solar corona.

    Respectfully submitted,
    Steve


    Edit: More nifty wiggling video from NASA Goddard.
    http://io9.com/5869006/best-look-yet-of-comet-lovejoys-slingshot-around-the-sun

    ...and a beautiful HINODE shot of the nucleus and innermost coma near the face of the sun. My golly!
    http://sungrazer.nrl.navy.mil/index.php?p=images/lovejoy/hinode_sot.png
     
    Last edited by a moderator: May 5, 2017
  6. Dec 19, 2011 #5
    That's amazing!
     
  7. Dec 19, 2011 #6

    Dotini

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    Re: Icy(?) Comet Survives Passage thru Solar Corona

    http://www.spaceweather.com/images2011/18dec11/spiraltail_strip.jpg
    I like these three shots in extreme ultraviolet. NASA are asking what makes the comet's tail wiggle so wildly?

    Another fragmentary entry from the SOHO/STEREO mission blog:

    Another surprise was how Lovejoy has both regained and sustained its intense pre-perihelion brightness. As it raced through the solar corona, Lovejoy's extensive dust tail was completely severed, and thereafter gently floated towards the Sun while its head raced one without it. As it re-emerged from perihelion, all that remained was an intense, condensed nucleus that seemed a shadow of its former self. But within just three-and-a-half hours, it underwent a sepctacular resurgence to return to its former glory! I really did not see that coming, nor did I envision that it would become as bright as when it plunged in, that its tail would re-grow so strongly, that its ion tail (the thin one you see here) would strengthen more than ever, and that it would begin to grace the Southerh Hemisphere skies as it is now beginning to do. http://sungrazer.nrl.navy.mil/index.php?p=news/birthday_comet

    Respectfully,
    Steve
     
    Last edited: Dec 19, 2011
  8. Dec 21, 2011 #7

    Dotini

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    Last edited: Dec 21, 2011
  9. Dec 21, 2011 #8

    Drakkith

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    Nice video of the comets tail!
     
  10. Dec 21, 2011 #9

    Dotini

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    From the STEREO mission blog...

    http://sungrazer.nrl.navy.mil/images/lovejoy/lovejoy_20111215b_cor1.mov
    This is the SECCHI COR-1 (inner coronagraph) image on the STEREO-B satellite. From the perspective of STEREO-B, the comet moved diagonally across the face of the Sun, looped around it, and re-emerged from around the back. The comet is obvious to see as it enters the camera in the lower right. We lose sight of the head of the comet at ~2300UT as it disappears behind the occulting disk. (We superimposed a Sun image on the movie -- this camera doesn't actually see that.) Then at around 0130UT we see the bright tail of the comet appear again in the upper-left of the image and continue to move out. Here's the fun part: this is not the comet itself! Keep watching, and at ~0530UT you'll see the comet -- minus a tail! -- emerge on the right hand side of the central disk and move towards the lower-right of the image, finally exiting at ~10:45UT.

    So if the comet re-emerges on the right without its tail, does that mean the bright thing that flew out of the top-left of the image is its tail?? Absolutely! I summarize the situation here. What we're seeing is the comet streaming into our field of view with a vast cloud of dust and ice trailing in its wake. The comet reaches the Sun, loops sharply around it, and head out around the back of the Sun. But the tail material we see has already left the comet and is just going to carry on in a straight line from the time it was ejected, while at the same time be pushed away from the Sun by the radiation pressure from the Sun itself. So we're actually seeing the tail material sweeping out towards us, while the comet races off to do its own thing.

    OK, why does Lovejoy not have a tail after it reappears? How did it get torn off? Well it didn't actually get "torn off", as it was never physically connected to begin with, but what likely happened was that the dust and ice produced by the comet was no longer able to follow the comet in its path as the relatively dense and incredibly hot solar corona "captured" (probably instantaneously evaoprated) any dust and ice particles released by Lovejoy's nucleus. As Lovejoy gradually left the intense near-Sun environment, the dust and ice were gradually able to rebuild, now free of whatever impeding factor the solar corona was presenting it. Within a matter of hours it was again sporting a beautiful tail.

    The physics of all of this are uncertain and somewhat unknown. We are only just beginning to start unravelling the mystery, and this is going to take many months and many scientists.
    http://sungrazer.nrl.navy.mil/index.php?p=news/birthday_comet

    Respectfully submitted,
    Steve
     
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